All posts by alisterchapman

Free Sony FX6 and FX3 Tutorial Videos

Screenshot-2021-10-15-at-17.58.11-copy-600x328 Free Sony FX6 and FX3 Tutorial Videos

Hidden away in the Sony Alpha Academy are 6 tutorial videos that I made for the the Sony Cinemaline cameras, most notably the FX6 and FX3. These videos mainly cover the FX6 but information on the FX3 (and FX9) is also included in several of the videos..

The 6 videos cover the following subjects:

FX6 – Scan Modes and Codecs (including information of recording media)
FX6/FX3 – What is S-Cinetone.
FX6 – How to use the Cine-EI mode to shoot S-Log3.
FX6/FX3 – Slow Motion and Timelapse.
FX6/FX3 – Exposure tools (covering waveform and histogram as well as Zebras)
FX6/FX3 – Post Production Stabilisation.

To watch these video you will need to setup a free account with Sony. Then go to the Alpha Academy page linked below and scroll down to the FilmMaking section and then open the My Sony Expert tab.

https://www.sony.co.uk/alphauniverse/alpha-academy/videos

DaVinci resolve Frame Rendering Issue and XAVC

There is a bug in some versions of DaVinci Resolve 17 that can cause frames in some XAVC files to be rendered in the wrong order. This results in renders where the resulting video appears to stutter or the motion may jump backwards for a frame or two. This has now been fixed in version 17.3.2 so all user of XAVC and DaVinci Resolve are urged to upgrade to at least version 17.3.2.

https://www.blackmagicdesign.com/uk/support/family/davinci-resolve-and-fusion

SDI Failures and what YOU can do to stop it happening to you.

Sadly this is not an uncommon problem. Suddenly and seemingly for no apparent reason the SDI output on your camera stops working. And this isn’t a new problem either, SDI ports have been failing ever since they were first introduced. This issue affect all types of SDI ports. But it is more likely with higher speed SDI ports such as 6G or 12G as they operate at higher frequencies and as a result the components used are more easily damaged as it is harder to protect them without degrading the high frequency performance.

Probably the most common cause of an SDI port failure is the use of the now near ubiquitous D-Tap cable to power accessories connected to the camera. The D-Tap connector is sadly shockingly crudely designed. Not only is it possible to plug in many of the cheaper ones the wrong way around but with a standard D-Tap plug there is no mechanism to ensure that the negative or “ground” connection of the D-Tap cable makes or breaks before the live connection. There is a however a special but much more expensive D-Tap connector available that includes electronic protection against this very issue – see: https://lentequip.com/products/safetap

Imagine for a moment you are using a monitor that’s connected to your cameras SDI port. You are powering the monitor via the D-Tap on the cameras battery as you always do and everything is working just fine. Then the battery has to be changed. To change the battery you have to unplug the D-Tap cable and as you pull the D-Tap out, the ground connection disconnects fractionally before the live connection. During that moment there is still positive power going to the monitor but because the ground on the D-Tap is now disconnected the only ground route back to the battery becomes via the SDI cable through the camera. For a fraction of a second the SDI cable becomes the power cable and that power surge blows the SDI driver chip.

After you have completed the battery swap, you turn everything back on and at first all appears good, but now you can’t get the SDI output to work. There’s no smoke, no burning smells, no obvious damage as it all happened in a tiny fraction of a second. The only symptom is a dead SDI.

And it’s not only D-Tap cables that can cause problems. A lot of the cheap DC barrel connectors have a center positive terminal that can connect before the outer barrel makes a good connection. There are many connectors where the positive can make before the negative.

It can also happen when powering the camera and monitor (or other SDI connected devices like a video transmitter) via separate mains adapters. The power outputs of most of the small, modern, generally plastic bodied switch mode type power adapters and chargers are not connected to ground. They have a positive and negative terminal that “floats” above ground at some unknown voltage. Each power supplies negative rail may be at a completely different voltage compared to ground.  So again an SDI cable connected between two devices, powered by different power supplies will act as the ground between them and power may briefly flow down the SDI cable as the SDI cables ground brings both power supply negative rails to the same common voltage. Failures this way are less common, but do still occur. 

For these reasons you should always connect all your power supplies, power cables and especially D-Tap or other DC power cables first. Then while everything remains switched off connect the SDI cables. Only when everything is connected should you turn anything on. If unplugging or re-plugging a monitor (or anything else for that matter) turn everything off first. Do not connect or disconnect anything while any of the equipment is on.  Although to be honest the greatest risk is at the time you connect or disconnect any power cables such as when swapping a battery where you are using the D-Tap to power any accessories. So if changing batteries, switch EVERYTHING off first, then disconnect your SDI cables before disconnecting the D-Tap or other power cables next.

(NOTE: It’s been brought to my attention that Red recommend that after connecting the power, but before connecting any SDI cables you should turn on any monitors etc. If the monitor comes on OK, this is evidence that the power is correctly connected. There is certainly some merit to this. However this only indicates that there is some power to the monitor, it does not ensure that the ground connection is 100% OK or that the ground voltages at the camera and monitor are the same. By all means power the monitor up to check it has power, then I still recommend that you turn it off again before connecting the SDI).
 
The reason Arri talk about shielded power cables is because most shielded power cables use connectors such as Lemo or Hirose where the body of the connector is grounded to the cable shield. This helps ensure that when plugging the power cable in it is the ground connection that is made first and the power connection after. Then when unplugging the power breaks first and ground after. When using properly constructed shielded power cables with Lemo or Hirose connectors it is much less likely that these issues will occur (but not impossible).

Is this an SD fault? No, not really. The fault lies in the choice of power cables that allow the power to make before the ground or the ground to break before the power breaks.  Or the fault is with power supplies that have poor or no ground connection. Additionally you can put it down to user error. I know I’m guilty of rushing to change a battery and pulling a D-Tap connector without first disconnecting the SDI on many occasions, but so far I’ve mostly gotten away with it (I have blown an SDI on one of my Convergent Design Odysseys).

If you are working with an assistant or as part of a larger crew do make sure that everyone on set knows not to plug or unplug power cables or SDI cables without checking that it’s OK to do so. How many of us have set up a camera, powered it up, got a picture in the viewfinder and then plugged an SDI cable between the camera and a monitor that doesn’t have a power connection yet or already on and plugged in to some other power supply? Don’t do it! Plug and unplug in the right order – ALL power cables and power supplies first, check power is going to the camera, check power is going to the monitor, then turn it all off first, finally plug in the SDI.

New LUTs from Sony

Side-by-Side2_small-600x338 New LUTs from Sony

 

I was asked by Sony to produce a couple of new LUT’s for them. These LUT’s were inspired by many recent blockbuster movies and have been named “Space Adventure” and “Super Hero”.

Both LUT’s are available for free and there is a link on the page linked below that will allow you to obtain them.

Rather than explain the two different looks here go to this page on the Sony website https://pro.sony/en_GB/filmmaking/filmmaking-solutions/full-frame-cinematic-look

Scroll down to where it says “Stunning Cinematic Colour” and there you will find a video called “Orlaith” that shows both LUT’s applied to the same footage.

Orlaith is a gaelic name  and it is pronounced “orla”. It is the name of a mythical golden princess. The short film was shot on a teeny-tiny budget in a single evening with an FX3 and FX6 using S-Log3 and SGamut3.cine. Then the LUTs were applied directly to the footage with no further grading.




 

PXW-FX9 Version 3 Firmware Update Latest News

No, it hasn’t been released yet.  And it’s now not expected to arrive before the end of November. But it will be worth the wait.

We already knew about some of the new features but there is much more to this release than first announced. Let’s take a look:

Touch to focus, focus tracking: Yes, you heard it right. You will be able to use the touch sensitive LCD to touch on an object in the shot and then the camera will track that object as it moves around the shot. A box will appear around the touched object and you will be able to monitor what the AF is focussing on by looking at what the tracking box is over. This is a feature available on the A7S3 and FX3 that is VERY useful.

Anamorphic De-Squeeze. It will become much easier to shoot anamorphic with the FX9. When shooting Anamorphic the image produced by the lens is squeezed horizontally, and that’s what you record. But to monitor it correctly you then need to de-squeeze it by squashing it vertically by the correct amount. The V3 firmware update will allow the image to be squashed vertically (de-squeezed) for the LCD viewfinder so you can view with the included VF in the correct widescreen aspect ratio. Do note however that the SDI and HDMI outputs will NOT be de-squeezed, so to monitor externally you will need a monitor with de-squeeze, but most of them have this these days.

Super 16 Scan Modes: The camera will gain a 2K center scan mode that can be used to shoot at up to 180fps in full HD. Using the center scan mode for slow motion above 60fps will eliminate the aliasing issues currently seen when using the 2K FF or 2K S35 scan modes. Additionally you will be able to use Sony’s 2/3″ B4 lens adapter. When using the B4 adapter the camera will support ALAC  which corrects for chromatic aberrations in lenses that support this feature.

Switch Scan Modes via Assignable Button: This has been something on everyone’s wish lists for years. Now at last you will be able to set up an assignable button to switch scan modes. 

Add Camera ID and Reel Numbers to Clip Names: You will be able to use clip names that are prefixed by a camera ID number and a reel number similar to the clip naming system on the FS7.

Modify the Status Page List: This function allows you to remove pages from the status page menu. So you will be able to remove the pages you rarely use.

DC IN Alarm: Don’t get too excited just yet, but in V3 you will be able to set a low voltage alarm for the cameras DC input as well as the extension units DC input. This does NOT mean that there will be a low voltage warning with the current 3rd party V-Lock battery adapters as these convert the battery voltage to a fixed 19.5v supply that never changes. But it does mean that a clever manufacturer could now design a V-Lock adapter that could reduce it’s output voltage when the voltage of the V-Lock battery gets low allowing you to have an alarm in the camera before the battery cuts off.

Proxy Upload while recording: Currently you cannot upload proxies while recording. This will be improved in V3 and the camera will be able to upload proxies in the background while you are recording.

Zero Focus Distance function: When working with a lens that shows the focus distance on the LCD screen you will be able to focus on an object and then “zero” the focus distance. Then as you change the focus distance the the screen will display a +/- value that is how far from zero the focus is. You will be able to use this for a pull focus. Focus on the end object and set the focus distance to zero. Now focus on the start object. To pull focus turn the focus ring so you are back at zero again. Not actually sure how useful this will be, but hey – it isn’t costing us anything.

Change Network Settings via Mobile Phone App: You will be able to use a mobile phone to change the cameras network settings making it easier to enter addresses and passwords of FTP servers etc.

USB Phone tethering: you will be able to connect a couple of mobile phones to the camera via USB to use it them as modems for internet streaming (I believe this is via the USB ports on the top of the XDCA-FX9).

LCD Gamma Adjustments for SR Live: SR live is a type of HDR workflow developed for live productions that will be broadcast in both standard dynamic range and high dynamic range. This setting allows you to change the gamma of the LCD screen between SDR and HDR range when shooting using HLG in the HDR mode. This allows you to preview either what a viewer will see watching in SDR or a good approximation of what a viewer viewing in HDR will see.

S700 Remote Control: The camera will be able to be controlled remotely using s700 protocols (via ethernet).

KitPlus Show Twickenham 14/9/21

Screenshot-2021-09-10-at-10.17.51-600x316 KitPlus  Show Twickenham 14/9/21Just a quick note to tell you that I will be co-presenting a session at the Kit Plus show in Twickenham on Tuesday the 14th of September 2021. Philip Bloom on the subject of “Buying the right camera IS important – don’t get sucked into the marketing hype”.  We will be discussing how people make their purchasing decisions, what different manufacturers have to offer and debating – what does “cinematic” mean – if anything at all.

Come and join us it should be fun and it’s face to face!!

https://www.kitplus.com/events/KPS_London/97.html

Chroma Key and Greenscreen – Should I use S-Log3 or might Rec-709 be Better?

I’ve covered this before, but as this came up again in an online discussion I thought I would write about it again. For decades when I was doing a lot of corporate video work we shot greenscreen and chroma key with analoge or 8 bit, limited dynamic range, standard definition cameras and generally got great results (it was very common to use a bluescreen as blue spill doesn’t look as bad on skin tones as green). So now when we have cameras with much greater dynamic ranges and 10 bit recording is it better to shoot for greenscreen using S-Log3 (or any other log curve for that matter) or perhaps Rec-709?

Before going further I will say that there is no yes-no, right-wrong, answer to this question. I will also add that Rec-709 gets a bad rap because people don’t really understand how gamma curves/transfer functions actually work and how modern grading software is able to re-map the aquisition transfer function to almost any other transfer function. If you use a colour managed workflow in DaVinci Resolve it is very easy to take a Rec-709 recording and map it to S-Log3 so that you can apply the same grades to the 709 as you would to material originated using S-Log3. Of course the 709 recording may not have as much dynamic range as an S-Log3 recording, but it will “look” more or less the same.

Comming back to shooting greenscreen and chromakey:

S-Log3:
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Shoot using 10 bit S-log3 and you have 791 code values available (95-886) to record 14/15 stops of dynamic range. so on average across the entire curve each stop has around 55 code values. Between Middle Grey and +2 stops there are approx  155 code values – this region is important as this is where the majority of skin tones and the key background are likely to fall.

Rec-709:
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Shoot using vanilla Rec-709 and you are using 929 code values (90-1019) to record 6/7 stops so each stop has on average across the entire curve has around 125 code values. Between Middle Grey and +2 stops there are going to be around 340 code values.
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That is not an insignificant difference, it’s not far off the  difference between shooting with 10 bit or 12 bit.
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If you were to ask someone whether it is better to shoot using 10 bit or 12 bit I am quite sure the automatic answer would be 12 bit because the general concensus is – more bits is always better.
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A further consideration is that the Sony cameras operate at a lower ISO when shooting with standard gammas and as a result you will have an improved signal to noise ratio using 709 than when using S-log3 and this can also make it easier to achieve a good, clean, key.
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However you do also need to think about what it is you are shooting and how it will be used. If you are shooting greenscreen in a studio then you should have full control over your lighting and in most cases 6 or 7 stops is all you need, so Rec-709 should be able to capture everything comfortably well. If you are shooting outside with less control over the light perhaps Rec-709 won’t have sufficient range.
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If the background plates have been shot using S-Log3 then some people don’t like keying 709 into S-Log3. However a colour managed workflow can deal with this very easily. We should consider that 709 and S-Log3 in a workflow where grading is a big part should not be though of as “looks” but simply as transfer functions or maps of what brightness/saturation seen by the camera is recorded at what code value. Handle these transfer functions correctly via a colour managed workflow and both will “look” the same and both will grade the same within their respective capture limits.
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For an easy workflow you might chose to shoot the greenscreen elements using log with the same settings as the plates. There is nothing wrong with this, it works, it is a very commonly used workflow but it isn’t necessarily always going to be optimum. A lot of people will put a lot of emphasis on using raw or greater bit depths to maximise the quality of their keying, but overlook gamma choice altogether, simply because “Rec-709” is almost a dirty word these days.
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If you have more control, and want absolutely the best possible key, you might be better off using Rec-709. As you will have more data per stop which makes it easier for the keying software to identify edges and less noise. If using Rec-709 you want to chose a version of Rec-709 where you can turn off the camera’s knee as this will prevent the 709 curve from crushing the highlights which can make them difficult to grade. In a studio situation you shouldn’t need to use a heavy knee.

I suggest you experiment and test for yourself and not every situation will be the same, sometimes S-Log3 will be the right choice, other times Rec-709.
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Chroma Key and S-Cinetone

A question poped up today asking about how to expose S-Cinetone when shooting green screen. 
The answer is really quite simple – no differently to how you would expose S-Cinetone anywhere else. But, having said that it is important to understand that S-Cinetone is a bit different to normal Rec-709 and this needs to be considered when shooting for chroma key or green screen.

S-Cinetone’s highlight roll off and shoulder starts much lower than most “normal” rec-709 curves. From around 73% the gamma curve changes and starts to compress the levels and reduce contrast. In the shdows there is a variable toe that increases contrast at lower brightness levels. The nominal “normal” brightness levels are also lower, all part of the contemporary film like look S-Cinetone is designed to give. A 90% reflectivity reference white card would be exposed at approx 83% instead of the more normal 90% (if you were using a light meter you should end up with a 90% white card at 83IRE). A white piece of paper will be a bit brighter than this as printer and copier paper etc is designed to look as bright as possible, typically printer paper comes out around 3 to 5% brighter than a proper white card.

The lower start to the highlight roll-off means that if you place skintones around 70% the brighter parts of a face will be affected by the rolloff and this will make them flatter. Expose skin tones at 60% and the face will be more contrasty and in my opinion look better. Although darker this would still be well with the “normal” exposure range for S-Cinetone so you will not have excessive noise and it will still key well.

exposing-cinetone-600x316 Chroma Key and S-Cinetone

S-Cinetone would be considered correctly exposed when a 90% white card is exposed between 78% and 88%. This is quite a wide window and is due to the way S-Cinetone is designed to give differening contrast levels simply by exposing a touch brighter or darker. The variable toe and shoulder mean that exposing brighter will make the image flatter and exposing darker more contrasty. Exposing as you would with normal Rec-709 levels with a white card at 90% will place skintones rather higher than “normal” and they will appear very flat. So either expose so a white card falls in the 78-88% window or use a calibrated monitor to observe how the skin tone look and be careful not to overexpose them.

Your greenscreen should be between 40IRE and 60IRE for a good clean key, I normally aim for 50IRE with S-Cinetone, but provided you don’t go below 40IRE or above 60IRE you should be good.

Nanlite Forza 300 LED Spotlight

 The Nanlite Forza 300 is a LED COB spotlight normally used with a reflector to provide a 55 degree light cone.

Forza-2_2.3.1-600x338 Nanlite Forza 300 LED Spotlight
Nanlite Forza 300 spotlight with included reflector.

 

The lamp is 300 watts and can be powered from the mains with the included power adapter or vai a pair of V-lock batteries. It is daylight balanced at 5500K and has a CRI of 95 (measured by myself). It has always resulted in very pleasing skin tone whenever I have used it.

Forza-skin_1.12.1-600x338 Nanlite Forza 300 LED Spotlight
Skin tones look good when using the Forza 300 from Nanlite.

 

The 300 watt LED COB emitter produces a similar amount of light to a 3000 watt tungsten lamp. This  makes the Forza 300 suitable for illuminating very large areas or as a source light for a large soft box or for use with large silk diffusers. Nanlite make a very nice parabolic reflectors/soft boxes for the Forza lamps that are very quick to erect due to the use of clever quick locking support arms.

Parabolic-reflector_5.1.1-600x338 Nanlite Forza 300 LED Spotlight
Parabolic reflector/soft box for the Nanlite Forza 300

 

The lamphead has a standard Bowens mount so there are many light modifiers that can be used, but one that I particularly like is the Nanlite zoomable Fresnel adapter. This large fresnel lens can be adjusted to provide a very tightly controlled light beam from just 5 degrees wide to 45 degrees wide. It comes with barn doors and turns the Forza 300 into something comparable to the old Arri 2K fresnel, just without the heat and power draw.

Fresnelbarn-doors_3.1.1-600x338 Nanlite Forza 300 LED Spotlight
Nanlite zoomable fresnel lens with barn doors for the Forza 300 and Forza 500.

 

I’m a big fan of fresnels as they give you good control of where your light is going. Make it dimmable as well and you have a very versatile lamp.

The light can be controlled via DMX as well as a couple of very cheap wireless remote control units (around £20/$30) and an app is due to be released soon. 

Like many modern lights it also has a number of effects modes including strobe, storm, TV and bad bulb and these can be quickly and easily selected from the lamps control unit and power supply. The build quality is very good. The lamp head is mostly metal while the control unit is a mix of good quality plastics and metal.  The whole thing weighs 4.8kg so you don’t need a particularly large light stand to support it.

with a street price of around £650/$850 this is a very affordable yet also very capable lamp. I would suggest that anyone trying to build their own versatile light kit should include at least one spot light and not just rely on LED panel lights. Having a good, bright spot light allows you to a lot more creative lighting as a spot light, especially if you add the Fresnel lens can be used with gobo’s or objects in the foreground to create interesting shadow effects.

Grab3_3.16.1-600x338 Nanlite Forza 300 LED Spotlight

For a recent short film shoot I used the Forza 300 to throw light through a forest of trees. The trees creating interesting shadows adding a lot of extra contrast to the shots.  For another scene I used the Forza 300 as a backlight through some smoke for an interesting mystic effect. A flat panel light cannot reproduce these effects in the same way.

grab1_3.3.1-600x338 Nanlite Forza 300 LED Spotlight

For this shoot I needed to power the lamp off batteries. It is worth noting that if running the lamp at is maximum output of 300 watts you will be drawing over 10 amps from each of the 2 V-Lock batteries need to run it. This is right at the limit of what many V-Locks can deliver.  As a result you may find your batteries cutting off before they are fully discharged. To run a high power LED lamp like this you should consider Lithium Manganese batteries or other batteries capable of at least a 12 amp output. My own preference is to use Pag Paglink batteries as by linking two batteries together you can double the amount of power they can deliver. Using 4 Paglink batteries (2 pairs of 2) I was able to run the lamp for 90  minutes at full power.

4xpags_3.13.1-600x338 Nanlite Forza 300 LED Spotlight
4 Paglink batteries will power the Forza 300 for around 90 minutes.



The lamp I used for the review was supplied by Prolight Direct UK. They are very knowledgable with many years of experience with all kinds of film and television lighting, so do contact them with your lighting needs.

I highly recommend the Forza 300. It is, in my opinion, one of the best of this type of lamp on the market today and very competitively priced. Please see the video above for more information.

Nanlite.com