Category Archives: PXW-FS5

Treat it like a film camera!

If you have a modern camera that can record log or raw and has 13 stops or more of dynamic range you need to stop thinking “video” and think “film”.

A big mistake most traditional video camera operators make with these big DR cameras is to treat them as they would a typical limited dynamic range video camera and constantly worry and obsess about protecting highlights. Why do we do this? Well probably because that’s what you do with cameras with a very limited range and that’s probably what you have had drummed into you for years. But now with modern large sensor cameras everything changes. When you get to a 14 stop range camera, even if you choose to shoot 2 stops over exposed  (perhaps by using 500 EI on an FS7 or F5) you still have as much or more over exposure range as a conventional video camera and the highlight range that you do have is not subject to a knee or other similar acute highlight compression. So any highlights will contain a ton of high quality, usable picture information. By shooting over exposed by a controlled amount (1 to 2 stops), perhaps by using a low EI you gain very big improvements in the signal to noise ratio and get better saturated colors (opening the aperture lets more light onto the sensor, your colors will be better recorded). This allows you to pull a lot more information out of the data thin shadows and mid range. Most cameras that use log have very little data in the shadows. If you are recording with a 10 bit codec cameras that use variations of the Cineon log curve (Arri LogC, Sony S-Log3, Panasonic V-Log) only have about 80 luma shades covering the first 4 stops of exposure in total. Above the 4th stop the amount of data per stop increases rapidly so a little bit of deliberate over exposure really helps lift your darkest shadows up out of the noise and mire. Up in the highlights each stop has exactly the same amount of data, so over exposing a bit doesn’t compress the highlights as it would with a conventional camera, so a bit of mild over exposure is normally not noticeable.

Really with a 14 stop log camera you want to treat it like film, not video. Just like film, a 14 stop log camera will almost always benefit from a controlled amount of over exposure, highlights will rarely suffer or look bad just because you’re one stop hot, but he shadows and midtones will be significantly improved. And just like film, if you under expose log you will take a big hit. You will loose a lot of shadow information very quickly, have less color, it will be noisy and the highlight benefit will be marginal.

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Why It’s Helpful To Over Expose S-Log, Especially If You Only Have 8 Bit Recording.

This is something that keeps coming up in my workshops. It’s very important if shooting with S-Log2 or S-Log3 not to under expose and in most cases it can be highly beneficial to over expose a bit. Especially if you are using a camera like the A7s or FS5 in 4K when you only have 8 bit data.

S-log-levels Why It's Helpful To Over Expose S-Log, Especially If You Only Have 8 Bit Recording.

Take a look at this chart. It plots the S-Log2 and S-Log3 gamma curves on a log scale of f-stops against the amount of 10 bit or code values used to record each stop. The center line of the chart is middle grey. Both S-log2 and S-log3 provide 8 stops below middle grey and 6 stops above. Take a look at the darkest stop, the one that is -7 to -8 and look at how much data is allocated to that stop. With 10 bit recording you have according to this chart about 10 code values for S-Log2 and about 20 for S-Log3. That’s if you have 10 bit, and it’s not a lot of data. Admittedly there isn’t going to be a great deal of scene information in that darkest stop, deep in the shadows and the noise. But there’s part of the issue, the noise. If you have under exposed and you take this in to post and have to stretch out the shadows, the noise in these darkest shadows is going to look pretty coarse because it hasn’t been recorded with many shades/steps so stretching it out will make even “rougher” for want of a better term. If you are recording with 8 bit the problems is even worse. With 8 bit, S-Log2 will only have around 2 or 3 code values for that bottom stop, in effect the noise will have two values – black or +1 stop. Imagine how nasty that will look if you need to raise or stretch you blacks because you are under exposed, it will become very blocky and grainy.

The solution is to over expose a bit. By over exposing your footage by a stop when you go in to post production you will in most cases be bringing your levels down. So instead of stretching the noise out and making it worse you will be shrinking it down and reducing the negative impact it has on it’s image. Because cameras like the FS5, A7s etc have 14 stops of dynamic range this small bit of over exposure is going to make very little difference to your highlights in the vast majority of situations. Any slight over exposure you may have will likely look quite natural anyway, after all our own eyesight does also over expose, we don’t have unlimited dynamic range. On top of that the display technology does not exist to show a 14 stop range shot in it’s entirety and with natural contrast.

Which to buy F5, FS7 or FS5?

I’m only going to look at these 3 cameras in this article. Of course there are also many others to choose from these days, so do remember to look at other options from other manufacturers too.

I like Sony cameras and I’m not going to pretend otherwise. But I have to say that I really think Sony are on a roll right now. The PMW-F55, F5, FS7 and the FS5 are all great cameras. Sure there are cameras with more pixels and maybe more resolution that may or may not need full frame lenses. There are cheaper cameras and all kinds of other options, but these cameras are all good workhorse cameras that should prove reliable in the field and give years of good service (although with technology moving so fast you might not keep it for that many years).

So which to choose?

First of all YOU need to decided exactly what you need or want from your camera. It’s also good to separate out “What You Need” from “What You Would Like”. For example if you are on an extrmely tight budget you will need affordable media while you might also like the idea of being able to shoot continuously at 180fps. Sometimes the two are not compatible with each other, so you should go with the need rather than the like.

If you’re running a business then you should also ask yourself that all important question: Will the more expensive camera make me more money?

Yeah, yeah, I know…. for some of us they are our babies, our toys and it is nice to have the best toys. But don’t bankrupt yourself buying something you can’t afford or don’t really need.

I’ve included a table of differences between these cameras below which I suggest you take a look at.

The FS5 is clearly exceptional value for the money. It does 80-90% of what the other cameras can do. If you’re only ever going to shoot in HD and don’t want to use Cine EI or LUT’s then really the FS5 is probably all you’ll ever need. It’s small, compact, lightweight and has some great features for shooting on the move like the variable ND filter and face tracking autofocus (with a Sony lens). What it lacks however is 10 bit 422 recording in UHD (even the output is only 8 bit in 4K). So if you want to shoot in UHD (3840 x 2160 TV type 4K) then the amount of grading you can do will be a little restricted. It’s also unlikely to meet broadcast standards as a main camera for UHD production. Further more it also lacks a proper CineEI mode for S-log2/S-Log3 with LUT’s on the outputs.  This isn’t the end of the world for occasional log shoots but if you plan on shooting a lot of log then all of the other cameras will be easier to use and it will be easier to get the best results without having to mess about with external monitors with LUT’s, grey cards or light meters. It’s not so much the lack of LUT’s (there are viewfinder only gamma LUT’s) but the inability to monitor at anything other than the native ISO which makes it tougher to offset your exposure in the way you can with CineEI. One final and very important note about the PXW-FS5 is that the XAVC-L codec is very processor intensive. You will need a really good computer to do anything more than cuts only editing. The XAVC-I codec in the FS7, F5 and F55 is much easier to work with, but the files are bigger. SO while the FS5 may save you a lot in terms of media costs, you will need to spend money on a high spec, up to date PC or Mac if you don’t already have one.
The FS5 can be upgraded with a raw option that outputs 12 bit linear raw. This raw output can be recorded on an external recorder and in doing so bypasses many of the FS5’s internal limitations such as only being able to have a single video out OR monitoring signal when recording internally. The raw files are very, very big but you can convert the raw to 10 bit ProRes before recording on the external recorder and this does provide image quality close to the 10 bit internal recordings of the other cameras. But, by the time you add on the cost of the raw option, a raw recorder plus mounting, batteries and media, the price difference between the FS5 and FS7 is very small.

The FS7 really does sit in the middle of this bunch, both in terms of cost and features. It’s a bigger camera that’s tough to hand hold for long, really it’s a shoulder camera. It can do 95% of what the F5 and F55 can do and some things the F5 and F55 can’t. The use of the Sony E-Mount means you can add low cost Sony power zoom lenses or control Canon lens apertures via low cost and compact adapters, this is much harder (and more expensive) on the F5 and F55. Adapters for Canon lenses for the FS5 and FS7 start at $50 while for an F5/F55 adapter prices start at $800. In addition on the E-Mount cameras you can add speedbooster adapters for use with full frame lenses giving a wider field of view and 1 stop faster aperture.

The FS7 has a true CineEI mode for log shooting and can take custom LUT’s. It’s even possible to add the XDCA-FS7 adapter to get internal ProRes recording and a 12 bit raw output, but it is only 12 bit raw which although very nice, is a lot different to the far superior 16 bit raw from the F5 and F55. When using the XDCA-FS7 extension unit it’s also worth remembering that you need to use bulkier and generally more expensive V-Mount batteries.

The FS7 II adds an improved locking E-Mount for greater lens security and stability. The locking mount is also stronger than the standard mount so it will cope better with heavier lenses. In addition the FS7 II also has a variable ND filter. The variable ND allows you to do your fine exposure adjustments with the ND filter allowing the aperture to be used as a depth of field control.

The FS7 is great for short film production, it offers image quality that is good enough for a feature film (I don’t think a movie viewer would detect any deficiency in the pictures from a well setup and well used FS7, even on a big screen). The XQD media while not as cheap as the SDXC cards used by the FS5 is reasonably affordable. There are a few things that might frustrate some users, in particular it is a very sophisticated camera with lots of options and there is no easy way to see exactly how the camera is configured without interrupting the live image in the viewfinder either by going into the menus or using the status pages. If you do use a lot of the cameras features and modes, you will spend a lot of time in the menu system.

One of the great things about the  F5 or the more expensive PMW-F55 is the side display panel as this allows you to see how the camera is setup, which LUT you’re using, frame rates, audio levels and so much more without having to resort to the menus. You can also control most of the day to day functions that you will use from this side panel using the option menu and that makes the camera far easier and faster to use than the FS7. The F5/F55 lens mount is much stronger than the E-mount on the other cameras, so it’s better suited to heavy cinema lenses and large super 35mm zoom lenses. You can also adjust the back focus so that it works well with large cinema zooms. For exceptionally good HD images you have the extremely high quality SStP (HDCAM SR) codec. On top of that there is also a higher quality version of XAVC called XAVC Class 480. This brings some respectable improvements in image quality with only a small increase in file size, whether shooting in HD, UHD or 4K. For the very best 4K you have a full 16 bit linear raw option  when you dock the R5 raw recorder or with the R7 raw recorder you can choose between raw or 16 bit linear X-OCN. The R7 can shoot record in 4K at upto 120fps with the F55 for amazing slow motion. X-OCN offers images with quality comparable to 16 bit raw but with file sizes smaller than ProRes and not much bigger than XAVC.

Because the recorder docks directly to the camera it is much easier to use than the external cabled option for the FS7 or FS5. In addition the R5 and R7 recorders use special visually loss less processes to considerably reduce the file sizes and make the files very easy to handle. So if you want to shoot a lot of raw for the ultimate in post production flexibility the the F5/F55 are the obvious choice, although this comes at a price.

So, in summary I would suggest:

Buy the PXW-FS5, unless:

You need to shoot 4K DCI (4096×2160). You are going to shoot primarily using S-Log2/3 or do a lot of grading to your UHD footage or are planning to make broadcast ready UHD programs. Unless you need to shoot continuously in UHD faster than 30fps or faster than 60fps in HD. Need timecode in/out or genlock (needs XDCA-FS7 adapter on FS7). In this case I suggest you buy the FS7 unless:

You are going to shoot primarily in raw or need the convenience of the side status display (don’t underestimate how useful this can be). Unless you need to shoot anamorphic, with SStP (HDCAM SR) or need a 4K HDSDI output. Want integrated Genlock and Timecode In/Out. In this case buy the PMW-F5 (with 4K option?) unless:

You need an extra wide colour gamut and a global shutter, in which case the PMW-F55 is king of the hill.

FEATUREPXW-FS5PXW-FS7PMW-F5PMW-F55
SizeSmall handycamMedium Semi Shoulder CamMedium Shoulder CamMedium Shoulder Cam
Weight830g Body only
2.2kg ready to shoot*
2kg Body only
4kg Ready to shoot*
2.2kg Body only
4.8kg Ready to shoot*
2.2kg Body only
4.8kg Ready to shoot*
PowerBP-U type battery, 12 WattsBP-U battery, 20 Watts.V-mount battery, 25 watts.V-mount battery, 25 watts.
CodecXAVC-L 10 bit 422 HD, 8 bit 420 UHD
AVCHD
XAVC-I
XAVC-L
Mpeg2 HD
ProRes option
XAVC-I
XAVC-I Class 480
XAVC-L (30fps only)
Mpeg2 HD
SStP (HDCAM SR)
ProRes option
XAVC-I
XAVC-I Class 480
XAVC-L (30fps HD only)
Mpeg2 HD
SStP (HDCAM SR
ProRes option
Recording MediaSDXCXQDSxS or XQD via adapterSxS or XQD via adapter
Frame Rate/SizeHD up to 60fps
UHD up to 30fps.
HD up to 60fps
4K DCI and UHD to 60fps
HD up to 60fps.
4K DCI and UHD to 60fps (optional)
HD up to 60fps
4K DCI and UHD to 60fps
Slow Motion
Memory Buffer system up to 240fps HD, 960 fps at reduced resolution.Continuous 180fps
(240fps with ext raw)
Continuous 180fps
(2K 240fps with R5 raw recorder)
Continuous 180fps
(2K 240fps with R5 raw recorder, 4K 120fps with R7 recorder)
S-Log2/3 and wide gamut recording.YesYesYesYes
Ultra Wide color gamut sensor.NoNoNoYes (global shutter)
Cine EINoYesYesYes
LUT'sViewfinder gamma assist only.YesYesYes
User LUT'sNoYesYesYes
Auto FocusYes plus face trackingYesNoNo
Variable ND filterYesFS7 Mk1 - No
FS7 MkII - Yes
NoNo
Multiple SDI outputsNoYesYes (inc 4K HDSDI option)Yes (inc 4K HDSDI)
Advanced gamma curvesCinegamma x 4Hypergamma x 6Hypergamma x 6Hypergamma x 6
Native lens mountE-mountE-mountFZ Mount with PL adapterFZ mount with PL adapter
Anamorphic De-SqueezeNoNoYesYes
Side Panel Status DisplayNoNoYesYes
Quick access to menu functionsDirect MenuNoQuick Access Menu and Project Option MenuQuick Access Menu and Project Option Menu
Rec BT2020 supportNoNoNoYes
LANC remote controlYesYesNoNo
RMB remote controlNoNoYesYes
Viewfinder/LCD3.5" LCD + OLED EVF3.5" LCD with viewfinder loupe.3.5" LCD viewfinder or OLED viewfinder.3.5" LCD viewfinder or OLED viewfinder.
Built in Streaming/FtpYesNoNoNo

The Sony PXW-FS5. Run and Gun Super35 for all.

pxwfs5_side_150728_32-1024x745 The Sony PXW-FS5. Run and Gun Super35 for all.
The New Sony PXW-FS5

I was lucky enough to get some hands on time with a prototype FS5 in Amsterdam at IBC. In case you haven’t heard about it, the PXW-FS5 is a compact interchangeable lens, super 35mm camcorder from Sony that can record in HD or UHD 4K. It shares many of the features of the already incredibly popular PXW-FS7 but in a much smaller body. As well as being similar to the FS7 it also has many similarities with the lower cost FS700, more on that later.

SMALL AND VERY LIGHT.

The first thing that struck me about this camera is just how small and light it is. The top handle and handgrip can be removed making it even smaller and the body alone weighs just 800 grams. It really is very small and very light, so perfect for drones, gimbals or simply for those of us that want something compact for travel.

REMOVABLE HANDGRIP

On the right side of the camera there is a chunky handgrip with a host of assignable buttons, a zoom rocker, an assignable dial (ideal for exposure control) and a joystick for navigating through the cameras menus and controlling various functions. The handgrip is comfortable to hold and gives you a very secure grip of the camera. It can be rotated and locked into an wide range of positions so you can adjust it to suit your shooting style and how you’re using the camera. My only criticism of the hand grip is that for me and my big hands the record button was a little too recessed and could be tricky to press. Perhaps before the cameras are released this may be addressed.  The handgrip can be quickly detached via a quick release mechanism. The mounting system is very secure and I couldn’t find any play or wobble. Like the handgrip on the FS7 it uses the LANC protocol to control the camera and is connected via a 2.5mm plug. So this means that the majority of other existing LANC controllers can be used with the camera for remote control. Once the handgrip has been removed you can add a standard Arri rosette (not supplied, but available from Sony as a spare part) to attach the arm and controller from the FS7 or any other arms or attachments that use the Arri rosette standard.

FS5-Sony-grip-rosette-1024x542 The Sony PXW-FS5. Run and Gun Super35 for all.
Details of the detachable handgrip.

THE LEFT SIDE AND BUILD QUALITY

The left side of the camera is like a miniaturised FS7. There are several assignable buttons as well as the always familiar ENG style switches for gain and white balance. Above the switches there are push buttons for iris, shutter and gain control. There’s a dial and buttons for navigating the menu system (similar menu structure to FS700) and two large dials for setting the audio recording levels. On top of all that there is a large dial to control the iris/aperture or the electronic variable ND filter. Yes, that’s right an electronic variable ND… more on that later.

sony-fs5-6body-web-top-300x229 The Sony PXW-FS5. Run and Gun Super35 for all.
Top of the PXW-FS5 with the handle removed.

This camera is incredibly well built, it even has both 1/4″ and 3/8″ threads on the base as well as eight 1/4″ threads on the top of the body  for multiple mounting options on tripods as well as for attaching accessories such as lights or monitors. The body is lightweight magnesium alloy and to me it feels extremely well constructed. When I shot with it in Amsterdam it was raining heavily and it did get quite wet but that didn’t cause any problems. I would always recommend a rain cover, but sometimes you do get caught in unexpected rain showers.

POWER AND CONNECTIVITY, WIFI AND LAN

This is a 12v camera so for power the camera uses the now common BP-U type batteries as used on the EX1, PMW-200 etc. Or you can power it via a DC socket on the rear of the camera. Thanks to the low power electronics (approx 12 watts) a BP-U60 will run the camera for an incredible 4 hours. That’s almost double the run time of the already low powered FS7. So with one battery in the camera and a spare in your pocket you should have enough power for a full day of shooting. Connectivity is very good, there are two XLR audio inputs, one on the rear of the camera body and one on the right side of the removable handle. So even when you remove the top handle you can still attach an external XLR mic to the camera. On the top handle there is Sony’s MI shoe so you can add a radio mic or further XLR input box if you wish without extra wires or cables (the handle also includes a GPS receiver for adding your location to the footage metadata). On the back of the camera there is an HDSDI output and HDMI output. The SDI is HD only and the HDMI can be HD or 4K (UHD 8 bit, 4:2:2, 3840×2160) depending on the cameras shooting mode (Currently the HDMI/SDI output is not available when recording 4K internally. However a firmware update, version 1.1, will enable the HDMI/SDI while recording internally at a later date). It’s worth noting that there are no timecode or genlock inputs or outputs. In the future there will be a firmware option to add a raw output to the camera for the best possible image quality (there may or may not be a charge for this upgrade and I don’t know when it will be available). As well as the traditional video connections there is also a full size LAN port. The camera has wifi too, so you can connect to the internet or a network via either WiFi or a LAN cable and then use it’s built in streaming capability to stream your footage live or upload it via ftp at a later time. This is going to be great for breaking news or to stream corporate events for clients. Next year I’m going to try to stream the Northern Lights live from Norway.

SENSOR AND SENSITIVITY

pxwfs5_others_150728_42-Mid-300x228 The Sony PXW-FS5. Run and Gun Super35 for all.
Left side of the PXW-FS5

The sensor appears to be the same sensor as the PXW-FS7 and PMW-F5, so it’s a dedicated 4K video sensor. This means that compared to most DSLR’s and many other large sensor cameras it has minimal image skew and low levels of rolling shutter. When I shot with it I didn’t find any shots that were noticeably effected by rolling shutter even though I shot a lot of footage from a moving boat. Noise levels are well controlled even though the native ISO is 3200 ISOin S-Log and 1000 ISO in other gammas! It looks like the image processing in this camera is really rather good at reducing noise. In low light and the dark the pictures from this camera look very good. My understanding is that in order to keep the power consumption down and to keep heat levels low this camera uses different processing to the FS7.

FS5-night-1-1024x576 The Sony PXW-FS5. Run and Gun Super35 for all.
Ungraded frame grab from the pre-production PXW-FS5. Note how little noise there is. Click on the image for the full size frame.

This makes sense as this camera does not have some of the more advanced functions of the FS7, like the CineEI mode, but on a camera like this the simpler menu structure and less complicated shooting modes really come in to their own as it helps make it a very easy camera to use. And for me, this was one of the best surprises with this camera. It’s very easy to use!

EASY TO SHOOT WITH

I had the 18-105mm power zoom lens which is available with the camera in the PXW-FS5K “kit”. It has to be said that this isn’t a high end cinema lens. It’s a low cost DSLR type lens with a powered zoom function. It’s a constant f4 throughout the zoom range but still small and compact. The camera includes electronic lens compensation that helps reduce some of the distortions and vignetting that would otherwise be visible (this does work in both HD and 4K with this camera). In addition with a Sony lens you can choose via the menu which direction the focus ring operates in. When paired together like this it’s almost like having an ENG handycam camera like the EX1 or PMW-200 again. You get a smooth power zoom that tracks focus reasonably well in a very compact package. OK, so it’s only a 6x optical zoom and the focus ring is one of those uncalibrated round and round servo jobs, but you know what, it works and it works pretty well. The camera even has Sony’s clear image zoom function that electronically increases the zoom range with virtually no image degradation. Apparently this can even be used with a prime lens to make it into a short zoom, although I was unable to test this clever feature out for myself. Once the production cameras come out I’ll be sure to try this!

The autofocus is pretty good too! The camera has Sony’s face tracking auto focus which is great for shooting people on the go as it locks on to faces and will ignore the background etc.  Turn off the face tracking and you have a smooth and accurate autofocus system. Add in image stabilisation as well and for run and gun this really starts to make a compelling package that could be handed off to an assistant or less experienced operator for some B roll.

sony_pxw-fs5_smart_side-cover-1078x516-1024x490 The Sony PXW-FS5. Run and Gun Super35 for all.
The PXW-FS5 with 18-105mm power zoom.

LIMITATIONS COMPARED TO THE FS7

What about the limitations? Compared to the FS7 there are a few limitations. The codec options are all long GOP. You can choose between AVCHD or XAVC-L. There is no option for XAVC-I and in part that’s because this camera records to SD cards (SDXC for XAVC-L). There are two card slots so you can have either relay (one card after the other) or simultaneous recording to provide an instant backup. It’s nice to be able to use such cheap media, provided you remember that this is low cost consumer media, not really designed for professional applications. SD cards are normally very reliable provided you buy good quality cards from a reputable source.

Each card slot can be independently controlled by the hand grip rec button, the top handle rec button or body rec button if you wish. Back to the codec…. XAVC-L is a great codec. In HD it’s 10 bit 422 at up to 50Mb/s so offers full broadcast quality recording. In UHD (4K, 3840×2160) it is only 8 bit 4:2:0 at 100Mb/s so a little more restricted. But don’t panic! The 8 bit UHD recordings look beautiful. They are packed with detail and have rich well balanced color. I think it’s also worth remembering that like most 4K cameras this uses a bayer sensor, so you never have a true full chroma resolution equivalent of a 444 or even 422 signal off the sensor to record anyway. One small but important point to consider is that a Long GOP codec needs a more powerful computer to decode than an I Frame codec. So to edit the 4K (UHD only, no DCI 4K in the FS5) from this camera you will need an up to date and reasonably high spec computer. My retina MacBook Pro will play back and edit a single stream without issue, but start trying to use multiple layers or grading and adding filters and it will start to drop frames. One further limitation of the FS5 is that the highest base frame rate in 4K is 30fps. So you can shoot at 24, 25 or 30fps in 4K  at 100Mb/s or 24, 25, 30, 50 or 60fps in HD at 50 or 35 Mb/s XAVC-L or AVCHD (1920×1080 @ 17/24/28 Mb/s, plus 1280×720 @ 9/17/24Mb/s) or an AVCHD proxy for ftp or streaming at (it’s a multi-region camera).

SUPER SLOW MOTION

You can however shoot at up to 960fps by using the S&Q motion mode. This mode operates in almost exactly the same way as the FS700. It’s HD only. Up to 60fps the camera can record continuously, there is no sound however. Above 60 fps the camera uses an internal memory buffer to cache the super slow motion content. This means that at 240 fps, which is the fastest full HD speed, the camera can record up to 8 seconds of action. You have a choice of a start trigger which starts the 8 second record period when you press the rec button or an end trigger. If you use the end trigger you can wait for the action to happen, then press the rec button and the 8 seconds prior to pressing rec is then transferred to the SD cards. At 240fps 8 seconds of action becomes an 80 second clip. At 480 fps the sensor is read at half HD vertical resolution, at 960 fps the resolution is about 1/4 HD and it gets pretty grainy looking.

PICTURE PROFILES, S-LOG AND GAMUT

The PXW-FS5 includes picture profiles that have a number of preset “looks” straight from the factory. But you can go in to each of these picture profiles and change the gamma, colorspace, matrix and many other image quality settings. The FS5 has Cinegammas and S-Log2, S-Log3 as well as S-Gamut, S-Gamut3 and S-Gamut3.cine (some of these options may not be in the camera at launch, maybe only S-Log3/S-Gamut3.cine, the others added later). The Cinegammas are great for projects that won’t be graded or only have minimal grading. S-Log2/3 are fantastic for film projects or other higher end work that will be graded as it allows the full dynamic range (14 stops) of the camera to be captured. In HD the 10 bit recordings are going to be fantastic with S-log3 or S-Log2. In UHD the 8 bit recordings will be a bit more restrictive when it comes to heavy grading or post production work. S-Log2 is better than S-log3 when you only have 8 bit data as it uses all of the data available. But as a test I decided to record some S-Log3 with the FS5 and then grade it to see how it holds up. I was really very pleasantly surprised. Get the exposure right and it works well and can produce a beautiful image provided you don’t push the grade too far. When shooting in S-Log you can add a gamma assist LUT to the viewfinder to make exposure assessment easier. At the moment there is only one LUT which is the 709(800) LUT. This corrects the gamma in the viewfinder to a much more normal looking image to make getting your exposure right much simpler. I noticed that the cameras Histogram always measures the recorded signal. I think this LUT is going to be the key way of getting good log exposure with this camera, but it’s also very simple to use and that’s what you need for run and gun. Add the LUT and if it looks right, it is right, it really is that simple. The camera will feature an enhanced zebra function that will operate over the full brightness range of 9 to 109 IRE and when the histogram is used you can include a marker line at the zebra level, so if you want to use a grey card or white card to set your log exposure this will be possible (this feature wasn’t working on the review sample so I have not tested it yet). There is no CineEI mode in the FS5.

The images from the PXW-FS5 really are very nice indeed. They contain lots of very fine detail and nice rich colors. The camera I had was a pre-production prototype, so there will be some tweaking of the image before launch, but I really hope that Sony don’t change it too much as it really looks great already. There is a little noise at 3200 ISO but the noise has a very fine grain and is not at all unpleasant. You can use a lower ISO if you want, even when shooting in S-log. Once the production cameras are available I will investigate the best ways to get the most out of the standard gammas and log gammas.

Ungraded-S-log-FS5-1024x576 The Sony PXW-FS5. Run and Gun Super35 for all.
Ungraded S-Log3 frame grab fro a prototype PXW-FS5. Click on the image for the full size. Note THIS IS A JPEG so will contain artefacts not in the original image.
FS5-graded-2-1024x576 The Sony PXW-FS5. Run and Gun Super35 for all.
Graded S-log3 from the PXW-FS5. Click on the image for the full size frame. Note THIS IS A JPEG so will contain artefacts not in the original footage.

CENTER SCAN MODE

FS5 has a center scan mode that uses just the center super 16mm sized part of the sensor. This mode is only available when shooting in HD, but the really nice thing is that you can assign the center scan mode to one of the assignable buttons and it switches instantly between full scan and center scan. This can be useful for extending your focal length electronically, in effect acting as a 2x extender. It means that if using the 18-105 lens for example you can get the equivalent of a 36 to 210 focal length by using the center scan mode. Another possibility is being able to use super 16mm lenses or even some 2/3″ ENG B4 zoom lenses. Super 16 is slightly larger than 2/3″ so not all 2/3″ lenses will be suitable, but many will be fine and won’t need an optical adapter, just a mount adapter.

THE LCD AND VIEWFINDER

For monitoring you have two options. There is a nice 3.5″ LCD panel (same panel as the FS7 perhaps) that can be attached to either the right, left, front or the rear of the hand grip. The LCD is plugged in to the side of the camera using the same connector as the FS7 viewfinder. The LCD can be rotated into a wide range of different positions for viewing from the rear, front or side of the camera. The attachment system and mount is well thought out and much better that the FS7’s viewfinder mounting system. The resolution is approx 1/4HD (960 x 540) which appears to be the norm for this size of LCD panel. On the back of the camera there is a small electronic viewfinder (EVF). This little EVF is actually rather good. It’s OLED so has great contrast and has a resolution very similar to the larger LCD panel. It is however quite small and you do need to get your eye nice and close to the EVF to get the best from it. I used it a lot for my shoot in Amsterdam.

VARIABLE ND FILTER

pxwfs5_3-300x300 The Sony PXW-FS5. Run and Gun Super35 for all.
The FS5 Has an electronic variable ND filter.

I’ve saved one of the best bits about this camera to last. It has an electronic variable ND filter. On the front of the camera there is a traditional looking filter wheel knob with 4 positions. In addition on the side of the camera there is an exposure adjustment wheel that can be used to control the iris or the ND filter! When the front ND filter wheel knob is set to clear the ND filter system is removed from the optical path. But in the other 3 positions the variable ND is placed between the lens and the sensor. It’s very important to understand that this is not a polarising ND filter as often used on the front of camera lenses. It is a special crystal that darkens when a voltage is applied to it that does not polarise the light. When the ND filter is in place it can be controlled either via the ND knob or the exposure dial. If controlled by the ND knob you can set the 3 selectable ND levels via the menu, so you can choose just how much ND you get at each of the 3 ND knob positions. If you use the wheel the you get smooth control of the ND from dark to near clear over what I believe is a 7 stop range. In the future there will be a firmware update to allow automatic control of the ND filter.

The FS5 uses what we know as Sony’s E-Mount (although Sony actually call the lens system the Alpha system). Because the sensor is very close to the lens mount it’s very easy to adapt from E-Mount to almost anything else, such as PL-Mount or Canon EF. As anyone that’s used a Canon EF lens or camera will know, the aperture on the Canon lenses operates in steps. This means that you can’t make a smooth exposure change mid shot. The variable ND filter on the FS5 gets around this problem very nicely as you can set you exposure with the aperture as you would normally and then use the ND filter for any mid shot exposure changes. The other nice thing about a variable ND is that it allows you to make exposure changes without altering your depth of field. It’s very clever technology that first appeared on the PXW-X180.

CONCLUSIONS

I think Sony really have a winner on their hands. The current FS7 is a great camera, but can be a bit bulky for run and gun, it’s a shoulder cam. The FS7 is a great digital cinema camera with 10 bit 422 4K DCI and UHD and full LUT and EI capabilities. The new PXW-FS5, while a little more limited as a digital cinema camera is much smaller and I think much easier to use for run and gun. The combination of the FS5 with the 18-105mm lens with it’s power zoom, effective autofocus, variable ND and really great handheld ergonomics make this a really easy camera to shoot with on the move. It really does remind me of the EX1 when that was launched.  At that time to get really good quality images you almost always had to use a shoulder mounted camera, but the EX1 changed that forever. Now we have broadcast quality handycams such as the PXW-X200 that are used day in, day out for news and documentary production. To me the FS5 is similar. Up to now the majority of high quality super 35mm cameras have been shoulder mounted or bulky. The Fs5 brings really exceptionally good image quality combined with ease of use into a truly useable handheld package for the first time.  While there are other small options such as the new Sony A7s2 they are not as ergonomic as the FS5 for video work, they don’t have XLR audio without the use of adapters, they don’t have conveniently located zoom rockers etc.

The FS5 is sure to be a hit. I have one on order.

Please remember that my review is based on a pre-production prototype camera. Some features and functions may change between now and release and options may or may not be added in later firmware updates. I have tried to be as accurate as possible and believe that everything is true and accurate, but things do change!
NORTHERN LIGHTS 2016.

Don’t forget I run storm chasing and Northern Lights expeditions every year. I still have some places on the second Northern Lights tour in Feb 2016. These are amazing expeditions by snowmobile up on to the Finnmarksvidda. We go ice fishing, dog sledding, exploring, cook a meal in a tent and enjoy traditional Norwegian saunas.

More information here.

sky-full-of-Aurora-1024x683 The Sony PXW-FS5. Run and Gun Super35 for all.
Northern Lights over our cabins in Norway.

 

More info on CMOS sensor grid artefacts.

Cameras with bayer CMOS sensors can in certain circumstances suffer from an image artefact that appears as a grid pattern across the image. The actual artefact is normally the result of red and blue pixels that are brighter than they should be which gives a magenta type flare effect. However sometimes re-scaling an image containing this artefact can result in what looks like a grid type pattern as some pixels may be dropped or added together during the re scaling and this makes the artefact show up as a grip superimposed over the image.

grid-pattern-1024x576 More info on CMOS sensor grid artefacts.
Grid type artefact.

The cause of this artefact is most likely off-axis light somehow falling on the sensor. This off axis light could come from an internal reflection within the camera or the lens. It’s known that with the F5/F55 and FS7 cameras that a very strong light source that is just out of shot, just above or below the image frame can in some circumstances with some lenses result in this artefact. But this problem can occur with almost any CMOS Bayer camera, it’s not just a Sony problem.

The cure is actually very simple, use a flag or lens hood to prevent off axis light from entering the lens. This is best practice anyway.

So what’s going on, why does it happen?sony-grid-artefact-explained More info on CMOS sensor grid artefacts.

When white light falls on a bayer sensor it passes through color filters before hitting the pixel that measures the light level. The color filters are slightly above the pixels. For white light the amount of light that passes through each color filter is different.  I don’t know the actual ratios of the different colors, it will vary from sensor to sensor, but green is the predominant color with red and blue being considerably lower, I’ve used some made up values to illustrate what is going on, these are not the true values, but should illustrate the point.

In the illustration above when the blue pixel see’s 10%, green see 70% and red 20%, after processing the output would be white. If the light falling on the sensor is on axis, ie coming directly, straight through the lens then everything is fine.

But if somehow the light falls on the sensor off axis at an oblique angle then it is possible that the light that passes through the blue filter may fall on the green pixel, or the light from the green filter may fall on the red pixel etc. So instead of nice white light the sensor pixels would think they are seeing light with an unusually high red and blue component. If you viewed the image pixel for pixel it would have very bright red pixels, bright blue pixels and dark green pixels. When combined together instead of white you would get Pink or Blue. This is the kind of pattern that can result in the grid type artefact seen on many CMOS bayer sensors when there are problems with off axis light.

This is a very rare problem and only occurs in certain circumstances. But when it does occur it can spoil an otherwise good shot. It happens more with full frame lenses than with lenses designed for super 35mm or APSC and wide angles tend to be the biggest offenders as their wide Field of View  (FoV) allows light to enter the optical path at acute angles. It’s a problem with DSLR lenses designed for large 4:3 shaped sensors rather than the various wide screen format that we shoot video in today. All that extra light above and below the desired widescreen frame, if it isn’t prevented from entering the lens has to go somewhere. Unfortunately once it enters the cameras optical path it can be reflected off things like the very edge of the optical low pass filter, the ND filters or the face of the sensor itself.

The cure is very simple and should be standard practice anyway. Use a sun shade, matte box or other flag to prevent light from out of the frame entering the lens. This will prevent this problem from happening and it will also reduce flare and maximise contrast. Those expensive matte boxes that we all like to dress up our cameras with really can help when used and adjusted correctly.

I have found that adding a simple mask in front of the lens or using a matte box such as any of the Vocas matte boxes with eyebrows will eliminate the issue. Many matte boxes will have the ability to be fitted with a 16:9 or 2.40:1 mask ( also know as Mattes hence the name Matte Box) ahead of the filter trays. It’s one of the key reason why Matte Boxes were developed.

IMG_1022 More info on CMOS sensor grid artefacts.
Note the clamp inside the hood for holding a mask in front of the filters on this Vocas MB216 Matte Box. Not also how the Matte Box’s aperture is 16:9 rather than square to help cut out of frame light.
SMB-1_mpa_04-1024x576 More info on CMOS sensor grid artefacts.
Arri Matte Box with Matte selection.

You should also try to make sure the size of the matte box you use is appropriate to the FOV of the lenses that you are using. An excessively large Matte Box isn’t going to cut as much light as a correctly sized one.  I made a number of screw on masks for my lenses by taking a clear glass or UV filter and adding a couple of strips of black electrical tape to the rear of the filter to produce a mask for the top and bottom of the lens. With zoom lenses if you make this mask such that it can’t be seen in the shot at the wide end the mask is effective throughout the entire zoom range.

f5-f55-mask More info on CMOS sensor grid artefacts.

Many cinema lenses include a mask for 17:9 or a similar wide screen aperture inside the lens.

 

Over and Under Exposure LUT’s for the PXW-FS7, PMW-F5 and PMW-F55

Here are two sets of LUT’s for use in post production with the PXW-FS7, PMW-F5 and PMW-F55.

These LUT’s are based around the Sony 709(800) LUT and the Sony LC-709TypeA LUT (Arri Alexa look). But in addition to the base LUT designed for when you shoot at the native ISO there are LUTs for when you shoot at a lower or higher EI.

When you shoot at a high or low EI the resulting footage will be either under or over exposed when you add the standard LUT. These LUT’s include compensation for the under or overexposure giving the best possible translation from SGamut3.cine/S-log3 to rec-709 or the Alexa look and result in pleasing skin tones and a nice mid range with minimal additional grading effort.

If you find these LUT’s useful please consider buying me a coffee or beer.


Type



pixel Over and Under Exposure LUT's for the PXW-FS7, PMW-F5 and PMW-F55

To download the 709(800) compensated LUTs: alisters 709 exposure compensated luts

To download the Arri look LUTs (LC709 TypeA): alisters arri look exposure compensated luts

What is a Gamut or Color Space and why do I need to know about it?

Well I have set myself quite a challenge here as this is a tough one to describe and explain. Not so much perhaps because it’s difficult, but just because it’s hard to visualise, as you will see.

First of all the dictionary definition of Gamut is “The complete range or scope of something”.

In video terms what it means is normally the full range of colours and brightness that can be either captured or displayed.

I’m sure you have probably heard of the specification REC-709 before. Well REC-709, short for ITU-R Recommendation, Broadcast Television, number 709. This recommendation sets out the display of colours and brightness that a television set or monitor should be able to display. Note that it is a recommendation for display devices, not for cameras, it is a “display reference” and you might hear me talking about when things are “display referenced” ie meeting these display standards or “scene referenced” which would me shooting the light and colours in a scene as they really are, rather than what they will look like on a display.

Anyway…. Perhaps you have seen a chart or diagram that looks like the one below before.

gamuts-269x300 What is a Gamut or Color Space and why do I need to know about it?
Sony colour gamuts.

Now this shows several things. The big outer oval shape is what is considered to be the equivalent to what we can see with our own eyes. Within that range are triangles that represent the boundaries of different colour gamuts or colour ranges. The grey coloured triangle for example is REC-709.

Something useful to know is that the 3 corners of each of the triangles are whats referred to as the “primaries”. You will hear this term a lot when people talk about colour spaces because if you know where the primaries (corners) are, by joining them together you can find the size of the colour space or Gamut and what the colour response will be.

Look closely at the chart. Look at the shades of red, green or blue shown at the primaries for the REC-709 triangle. Now compare these with the shades shown at the primaries for the much larger F65 and F55 primaries. Is there much difference? Well no, not really. Can you figure out why there is so little difference?

Think about it for a moment, what type of display device are you looking at this chart on? It’s most likely a computer display of some kind and the Gamut of most computer displays is the same size as that of REC-709. So given that the display device your looking at the chart on can’t actually show any of the extended colours outside of the grey triangle anyway, is it really any surprise that you can’t see much of a difference between the 709 primaries and the F65 and F55 primaries. That’s the problems with charts like this, they don’t really tell you everything  that’s going on. It does however tell us some things. Lets have a look at another chart:

Gamuts-1024x632 What is a Gamut or Color Space and why do I need to know about it?
SGamuts Compared.

This chart is similar to the first one we looked at, but without the pretty colours. Blue is bottom left, Red is to the right and green top left.

What we are interested in here is the relationship between the different colour space triangles.  Using the REC-709 triangle as our reference (as that’s the type of display most TV and video productions will be shown on) look at how S-Gamut and S-Gamut3 is much larger than 709. So S-Gamut will be able to record deeper, richer colours than 709 can ever hope to show. In addition, also note how S-Gamut isn’t just a bigger triangle, but it’s also twisted and distorted relative to 709. This is really important.

You may also want to refer to the top diagram as well as I do my best to explain this. The center of the overall gamut is white. As you draw a line out from the center towards the colour spaces primary the colour becomes more saturated (vivid). The position of the primary determines the exact hue or tone represented. Lets just consider green for the moment and lets pretend we are shooting a shot with 3 green apples. These apples have different amounts of green. The most vivid of the 3 apples has 8/10ths of what we can possibly see, the middle one 6/10ths and the least colourful one 4/10ths. The image below represents what the apples would look like to us if we saw them with our eyes.

apples1 What is a Gamut or Color Space and why do I need to know about it?
The apples as we would see them with our own eyes.

If we were shooting with a camera designed to match the 709 display specification, which is often a good idea as we want the colours to look right on the TV, the the greenest, deepest green we can capture is the 709 green primary. lets consider the 709 green primary to be 6/10ths with 10/10ths  being the greenest thing a human being can see. 6/10ths green will be recorded at our peak green recording level so that when we play back on a 709 TV it will display the greenest the most intense green that the display panel is capable of.  So if we shoot the apples with a 709 compatible camera, 6/10ths green will be recorded at 100% as this is the richest green we can record (these are not real levels, I’m just using them to illustrate the principles involved) and this below is what the apples would look like on the TV screen.

apples3 What is a Gamut or Color Space and why do I need to know about it?
6/10ths Green and above recorded at 100% (our imaginary rec-709)

So that’s rec-709, our 6/10ths green apple recorded at 100%. Everything above 6/10 will also be 100% so the 8/10th and 6/10ths green apples will look more or less the same.

What happens then if we record with a bigger Gamut. Lets say that the green primary for S-Gamut is 8/10ths of visible green. Now when recording this more vibrant 8/10ths green in S-Gamut it will be recorded at 100% because this is the most vibrant green that S-Gamut can record and everything less than 8/10 will be recorded at a lower percentage.

But what happens if we play back S-Gamut on a 709 display? Well when the 709 display sees that 100% signal it will show 6/10ths green, a paler less vibrant shade of green than the 8/10ths shade the camera captured because 6/10ths is the most vibrant green the display is capable of. All of our colours will be paler and less rich than they should be.

apples4 What is a Gamut or Color Space and why do I need to know about it?
The apples recorded using a big gamut but displayed using 709 gamut.

So that’s the first issue when shooting with a larger colour Gamut than the Gamut of the display device, the saturation will be incorrect, a dark green apple will be pale green. OK, that doesn’t sound like too big a problem, why don’t we just boost the saturation of the image in post production? Well if the display is already showing our 100% green S-Gamut signal at the maximum it can show (6/10ths for Rec-709) then boosting the saturation won’t help colours that are already at the limit of what the display can show simply because it isn’t capable of showing them any greener than they already look. Boosting the saturation will make those colours not at the limit of the display technology richer, but those already at the limit won’t get any more colourful. So as we boost the saturation any pale green apples become greener while the deep green apples stay the same so we loose colour contrast between the pale and deep green apples. The end result is an image that doesn’t really look any different that it would have done if shot in Rec-709.

apples31 What is a Gamut or Color Space and why do I need to know about it?
Saturation boosted S-Gamut looks little different to 709 original.
gamuts-269x300 What is a Gamut or Color Space and why do I need to know about it?
Sony colour gamuts.

But, it’s even worse that just a difference to the saturation. Look at the triangles again  and compare 709 with S-Gamut. Look at how much more green there is within the S-Gamut colour soace than the 709 colour space compared to red or blue.  So what do you think will happen if we try to take that S-Gamut range and squeeze it in to the 709 range? Well there will be a distinct colour shift towards green as we have a greater percentage of green in S-Gamut than we should have in Rec-709 and that will generate a noticeable colour shift and the skewing of colours.

apples5 What is a Gamut or Color Space and why do I need to know about it?
Squeezing S-Gamut into 709 will result in a colour shift.

This is where Sony have been very clever with S-Gamut3. If you do take S-Gamut and squeeze it in to 709 then you will see a colour shift (as well as the saturation shift discussed earlier). But with S-Gamut3 Sony have altered the colour sampling within the colour space so that there is a better match between 709 and S-Gamut3. This means that when you squeeze S-Gamut3 into 709 there is virtually no colour shift. However S-Gamut3 is still a very big colour space so to correctly use it in a 709 environment you really need to use a Look Up Table (LUT) to re-map it into the smaller space without an appreciable saturation loss, mapping the colours in such a way that a dark green apple will still look darker green than a light green apple but keeping within the boundaries of what a 709 display can show.

Taking this one step further, realising that there are very few, if any display devices that can actually show a gamut as large as S-Gamut or S-Gamut3, Sony have developed a smaller Gamut known as S-Gamut3.cine that is a subset of S-Gamut3.

The benefit of this smaller gamut is that the red green and blue ratios are very close to 709. If you look at the triangles you can see that S-Gamut3.cine is more or less just a larger version of the 709 triangle. This means that colours shifts are almost totally eliminated making this gammut much easier to work with in post production. It’s still a large gamut, bigger than the DCI-P3 specification for digital cinema, so it still has a bigger colour range than we can ever normally hope to see, but as it is better aligned to both P3 and rec-709 colourists will find it much easier to work with. For productions that will end up as DCI-P3 a slight saturation boost is all that will be needed in many cases.

So as you can see, having a huge Gamut may not always be beneficial as often we don’t have any way to show it and simply adding more saturation to a seemingly de-saturated big gamut image may actually reduce the colour contrast as our already fully saturated objects, limited by what a 709 display can show, can’t get any more saturated. In addition a gamut such as S-Gamut that has a very different ratio of R, G and B to that of 709 will introduce colour shifts if it isn’t correctly re-mapped. This is why Sony developed S-Gamut3.cine, a big but not excessively large colour space that lines up well with both DCI-P3 and Rec-709 and is thus easier to handle in post production.

Understanding Sony’s SLog3. It isn’t really noisy.

It’s been brought to my attention that there is a lot of concern about the apparent noise levels when using Sony’s new Slog3 gamma curve. The problem being that when you view the ungraded Slog3 it appears to have more noise in the shadows than Slog2. Many are concerned that this “extra” noise will end up making the final pictures nosier. The reality is that this is not the case, you won’t get any extra noise using Slog3 over Slog2. Because S-Log3 is closer to the log gamma curves used in other cameras many people find that Slog3 is generally easier to grade and work with in post production.

So what’s going on?

Slog3 mimics the Cineon Log curve, a curve that was originally designed, back in the 1980’s to match the density of film stocks. As a result the shadow and low key parts of the scene are shown and recorded at a brighter level than Slog2. S-Log2 was designed from the outset to work with electronic sensors and is optimised for the way an electronic sensor works rather than film. Because the S-Log3 shadow range has more gain than S-log2, the shadows end up a bit brighter than it perhaps they really needs to be and because of the extra gain the noise in the shadows appears to be worse. The noise level might be a bit higher but the important thing, the ratio between wanted picture information and un wanted noise is exactly the same whether in Slog2 or Slog3.

Let me explain:

The signal to noise ratio of a camera is determined predominantly by the sensor itself and how the sensor is read. This is NOT changing between gamma curves.

The other thing that effects the signal to noise ratio is the exposure level, or to be more precise the aperture and how much light falls on the sensor. This should be same for Slog2 and Slog3. So again no change there.

As these two key factors do not change when you switch between Slog2 and slog3, there is no change in the signal to noise ratio between Slog2 and Slog3. It is the ratio between wanted picture information and noise that is important. Not the noise level, but the ratio. What people see when they look at ungraded SLog3 is a higher noise level simply because ALL the signal levels are also higher, both noise and desirable image information. So the ratio between the wanted signal and the noise is actually no different for both Slog2 and Slog3.

Gamma is just gain, nothing more, nothing less, just applied by variable amounts at different levels. In the case of log, the amount of gain decreases as you go further up the curve.

Increasing or decreasing gain does NOT significantly change the signal to noise ratio of a digital camera (or any other digital system). It might make noise more visible if you are amplifying the image more than normal in an underexposure situation where you are using that extra gain to compensate for not enough light. But the ratio between the dark object and the noise does not change, it’s just that as you have made the dark object brighter by adding gain, you have also made the noise brighter by the same amount, so the noise also becomes brighter and thus more obvious.

Lets take a look at some Math. I’ll keep it very simple, I promise!

Just for a moment to keep things simple, lets say some camera has a signal to noise ratio of 3:1 (SNR is normally measured in db, but I’m going to keep things really simple here).

So, from the sensor if my picture signal is 3 then my noise will be 1.

If I apply Gamma Curve “A” which has 2x gain then my picture becomes 6 and my noise becomes 2. The SNR is 6:2 = 3:1

If I apply Gamma Curve “B” which has 3x gain then my picture becomes 9 and my noise becomes 3. The SNR is 9:3 = 3:1 so no change to the ratio, but the noise is now 3 with gamma B compared to  Gamma A where it is 2, so the gamma B image will appear at first glance to be noisier.

Now we take those imaginary clips in to post production:

In post we want to grade the shots so that we end up with the same brightness of image, so lets say our target level after grading is 12.

For the gamma “A” signal we need to add 3x gain to take 6 to 18. As a result the noise now becomes 6 (3 x 2 = 6).

For the gamma “B” signal (our noisy looking one) we need to use  less gain in post, only 2x gain, to take 9  to 18. When we apply 2x gain our noise for gamma B becomes 6 (2 x 3 = 6).

Notice anything? In both cases the noise in the final image is exactly the same, in both cases the final image level is 18 and the final noise level is 6, even though the two recordings started at different levels with one appearing noisier than the other.

OK, so that’s the theory, what about in practice?

Take a look at the images below. These are 400% crops from larger frames. Identical exposure, workflow and processing for each. You will see the original Slog2 and SLog3 plus the Slog 2 and Slog 3 after applying the LC-709 LUT to each in Sony’s raw viewer. Nothing else has been done to the clips. You can “see” more noise in the raised shadows in the untouched SLog3, but after applying the LUTs the noise levels are the same. This is because the Signal to Noise ratio of both curves is the same and after adding the LUT’s the total gain applied (camera gain + LUT gain) to get the same output levels is the same.

Slog2-400 Understanding Sony's SLog3. It isn't really noisy.
Slog3-400 Understanding Sony's SLog3. It isn't really noisy.Slog2-to-709-400 Understanding Sony's SLog3. It isn't really noisy.Slog3-to-709-400 Understanding Sony's SLog3. It isn't really noisy.

It’s interesting to note in these frame grabs that you can actually see that in fact the S-Log3 final image looks if anything a touch less noisy. The bobbles and the edge of the picture frame look better in the Slog3 in my opinion. This is probably because the S-Log3 recording uses very slightly higher levels in the shadow areas and this helps reduce compression artefacts.

The best way to alter the SNR of a typical video system (other than through electronic noise reduction) is by changing the exposure, which is why EI (Exposure Index) and exposure offsets are so important and so effective.

Slog3 has a near straight line curve above middle grey. This means that in post production it’s easier to grade as adjustments to one part of the image will have a similar effect to other parts of the image. It’s also very, very close to Cineon and to Arri Log C and in many cases LUT and grades designed for these gammas will also work pretty well with SLog3.

The down side to Slog3?

Very few really. Fewer data points are recorded for each stop in the brighter parts of the picture and highlight range compared to Slog2. This doesn’t change the dynamic range but if you are using a less than ideal 8 bit codec you may find S-Log2 less prone to banding in the sky or other gradients compared to S-Log3. With a 10 bit recording, in a decent workflow, it makes very little difference.

 

Correct exposure levels with Sony Hypergammas and Cinegammas.

When an engineer designs a gamma curve for a camera he/she will be looking to achieve certain things. With Sony’s Hypergammas and Cinegammas one of the key aims is to capture a greater dynamic range than is possible with normal gamma curves as well as providing a pleasing highlight roll off that looks less electronic and more natural or film like.

Slide3 Correct exposure levels with Sony Hypergammas and Cinegammas.
Recording a greater dynamic range into the same sized bucket.

To achieve these things though, sometimes compromises have to be made. The problem being that our recording “bucket” where we store our picture information is the same size whether we are using a standard gamma or advanced gamma curve. If you want to squeeze more range into that same sized bucket then you need to use some form of compression. Compression almost always requires that you throw away some of your picture information and Hypergamma’s and Cinegamma’a are no different. To get the extra dynamic range, the highlights are compressed.

exposure2-300x195 Correct exposure levels with Sony Hypergammas and Cinegammas.
Compression point with Hypergamma/Cinegamma.

To get a greater dynamic range than normally provided by standard gammas the compression has to be more aggressive and start earlier. The earlier (less bright) point at which the highlight compression starts means you really need to watch your exposure. It’s ironic, but although you have a greater dynamic range i.e. the range between the darkest shadows and the brightest highlights that the camera can record is greater, your exposure latitude is actually smaller, getting your exposure just right with hypergamma’s and cinegamma’s is very important, especially with faces and skin tones. If you overexpose a face when using these advanced gammas (and S-log and S-log2 are the same) then you start to place those all important skin tone in the compressed part of the gamma curve. It might not be obvious in your footage, it might look OK. But it won’t look as good as it should and it might be hard to grade. It’s often not until you compare a correctly exposed sot with a slightly over shot that you see how the skin tones are becoming flattened out by the gamma compression.

But what exactly is the correct exposure level? Well I have always exposed Hypergammas and Cinegammas about a half to 1 stop under where I would expose with a conventional gamma curve. So if faces are sitting around 70% with a standard gamma, then with HG/CG I expose that same face at 60%. This has worked well for me although sometimes the footage might need a slight brightness or contrast tweak in post the get the very best results. On the Sony F5 and F55 cameras Sony present some extra information about the gamma curves. Hypergamma 3 is described as HG3 3259G40 and Hypergamma 4 is HG4 4609G33.
What do these numbers mean? lets look at HG3 3259G40
The first 3 numbers 325 is the dynamic range in percent compared to a standard gamma curve, so in this case we have 325% more dynamic range, roughly 2.5 stops more dynamic range. The 4th number which is either a 0 or a 9 is the maximum recording level, 0 being 100% and 9 being 109%. By the way, 109% is fine for digital broadcasting and equates to bit 255 in an 8 bit codec. 100% may be necessary for some analog broadcasters. Finally the last bit, G40 is where middle grey is supposed to sit. With a standard gamma, if you point the camera at a grey card and expose correctly middle grey will be around 45%. So as you can see these Hypergammas are designed to be exposed a little darker. Why? Simple, to keep skin tones away from the compressed part of the curve.

Here are the numbers for the 4 primary Sony Hypergammas:

HG1 3250G36, HG2 4600G30, HG3 3259G40, HG4 4609G33.

Cinegamma 1 is the same as Hypergamma 4 and Cinegamma 2 is the same as Hypergamma 2.

All of the Hypergammas and Cinegammas are designed to exposed a little lower that with a standard gamma.

When should I use a Cinegamma or Hypergamma?

Cinegammas are designed to be graded. The shape of the curve with steadily increasing compression from around 65-70% upwards tends to lead to a flat looking image, but maximises the cameras latitude (although similar can be achieved with a standard gamma and careful knee setting). The beauty of the cinegammas is that the gentle onset of the highlight compression means that grading will be able to extract a more natural image from the highlights. Note than Cinegamma 2 is broadcast safe and has slightly reduced recording range than CG 1,3 and 4.

Standard gammas will give a more natural looking picture right up to the point where the knee kicks in. From there up the signal is heavily compressed, so trying to extract subtle textures from highlights in post is difficult. The issue with standard gammas and the knee is that the image is either heavily compressed or not, there’s no middle ground.

In a perfect world you would control your lighting (turning down the sun if necessary ;-o) so that you could use standard gamma 3 (ITU 709 standard HD gamma) with no knee. Everything would be linear and nothing blown out. This would equate to a roughly 7 stop range. This nice linear signal would grade very well and give you a fantastic result. Careful use of graduated filters or studio lighting might still allow you to do this, but the real world is rarely restricted to a 7 stop brightness range. So we must use the knee or Cinegamma to prevent our highlights from looking ugly.

If you are committed to a workflow that will include grading, then Cinegammas are best. If you use them be very careful with your exposure, you don’t want to overexpose, especially where faces are involved. getting the exposure just right with cinegammas is harder than with standard gammas. If anything err on the side of caution and come down 1/2 a stop.

If your workflow might not include grading then stick to the standard gammas. They are a little more tolerant of slight over exposure because skin and foliage won’t get compressed until it gets up to the 80% mark (depending on your knee setting). Plus the image looks nicer straight out of the camera as the cameras gamma should be a close match to the monitors gamma.