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What the hell is gamma anyway – video online now.

Last week I did an almost 2 hour long Webinar with Visual Impact on Gamma and gamma curves. The webinar was recorded and you can view the full session by following the link below.

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Black and White LUT set.

This was asked for on one of the online groups I follow. It’s a simple Black and White LUT that gives a wide dynamic range black and white image. The LUT has been designed to give a pleasing and gentle highlight roll-off with a reasonably contrasty mid range. I decided not to go too contrasty via the LUT so that more contrast can be added in post if needed. The output is legal range (broadcast safe). There is a single camera LUT for use in camera as well as a set of exposure compensated LUT’s going from -2 to plus 2 stops in half stop steps.

As always (to date at least) I offer these as a free download available by clicking at the bottom of the page. It takes time to create them and money to host them. I feel that this LUT set is worth $5.00 and would really appreciate that being paid if you find the LUT’s useful. But I will let you pay what you feel is fair, all contributions are greatly appreciated and it really does help keep this website up and running. If you can’t afford to pay, then just download the LUT’s and enjoy using them. If in the future you should choose to use them on a paying project, please remember where you got them and come back and make a contribution. More contributions means more LUT offerings in the future.

Please feel free to share a link to this page if you wish to share these LUT’s with anyone else or anywhere else.

To make a contribution please use the drop down menu here, there are several contribution levels to choose from.


Your choice:



pixel Black and White LUT set.

Click here to download AC Black and White LUT’s V1

SEE ALSO:

Film Emulation LUT’s set 1.

Venice Look LUT’s V3 (lower contrast and minus green)

Venice Look LUT’s V1 (high contrast)

HLG HDR LUT for FS7, F5 and F55.

WYSIWYG LUT’s (Designed to be baked in)

Film Emulation LUT’s for S-Log3 and S-Log2.

I’ve uploaded these LUT’s before, but they are tucked away under a slightly obscure heading, so here they are again!

There are 4 different LUTs in this set. A basic 709 LUT which is really good for checking exposure etc. It won’t give the best image, but it’s really good for getting your exposure just right. Diffuse white should be 85%, middle grey 43% and skin tones 65-70%.

Then there are 3 film emulation LUT’s that mimic 3 different types of film stock form different manufacturers. These are primarily designed for post production or for use on a client monitor on set. My recommendation is to use the 709 LUT for your viewfinder and exposure and then add the film emulation LUT later in post.

As always (to date at least) I offer these as a free download available by clicking on the links below. However a lot of work goes into creating and hosting these. I feel that this LUT set is worth $25.00 and would really appreciate that being paid if you find the LUT’s useful. Try them before you decide then pay what you feel is fair. All contributions are greatly appreciated and it really does help keep this website up and running. If you can’t afford to pay, then just download the LUT’s and enjoy using them, tell your friends and send them here. If in the future you should choose to use them on a paying project, please remember where you got them and come back and make a contribution. More contributions means more LUT offerings in the future.

Please feel free to share a link to this page if you wish to share these LUT’s with anyone else or anywhere else.

To make a contribution please use the drop down menu here, there are several contribution levels to choose from.


Your choice:



pixel Film Emulation LUT's for S-Log3 and S-Log2.

To download the Film Emulation LUT set please click the link: Film Emulation Luts

 

If you are looking for the Venice look LUTs:

Here are the links to my Venice Look Version 3 LUT’s. Including the minus green offset LUTs. Make sure you choose the right version and once you have downloaded them please read the README file included within the package.

Alister V-Look V3 LUT’s S-Log2/SGamut

Alister V-Look V3 LUT’s S-Log3/SGamut3.cine

 

Out and about with the PXW-Z280.

DSC_0037-1024x576 Out and about with the PXW-Z280.
Sony’s 4K PXW-Z280 handycam.

I have recently returned from a trip around Canada. While I was there I spent some more time shooting with Sony’s new PXW-Z280 handycam camcorder. This neat little camera continues to surprise me. I used a pre-production sample to shoot parts of an airshow in the summer and it worked really well. It was so easy to use, I had forgotten how much quicker it is to work with a camera with a 17x zoom lens compared to a large sensor camera with a very limited zoom range or prime lenses.

The Z280 uses 3x state of the art EMOR Stacked multi layer sensors. Each is full 4K, so you have full RGB 4K, unlike a single chip camera where the chroma resolution is much reduced by the bayer layout of the pixels. The 3 chip, full resolution design also means no aliasing in the color channels as is often typical of single chip designs.

The color splitting prism is more efficient than the absorption color filters on a single chip design, so more light gets to the pixels. The multi layer sensors have very good on-sensor processing so even though the pixels are rather small you get good sensitivity, low noise and good DR. The Z280 is approx  650-700 ISO with the base gammas so very close to an FS7 with it’s standard gammas and the colors match an FS7  extremely well. The picture look really nice.
DSC_0046-1024x576 Out and about with the PXW-Z280.
3x 4K sensors, 17x zoom and variable ND filter is a great combination on the PXW-Z280

From the testing I have done in the cameras dedicated HDR mode, where you can choose between HLG and S-Log3, with S-Log3 the DR of the Z280 appears to be around 13 stops, which is really quite remarkable for this type of camcorder. The sensor readout is very fast so rolling shutter is minimal.

When you factor in the Z280’s f1.9 lens, compared to an FS7 with the Sony F4 zoom or many other zooms that are typically around F4 the Z280 with it’s f1.9 lens does better in low light and offers similar DoF when both are wide open. Of course you can change the lens on an FS7 and use a faster lens, but then you won’t have anywhere near the zoom range of the Z280.
 

Like any small compact camera, it isn’t 100% perfect. Overall the lens is pretty good for a low cost 4K zoom, but like many 17x zooms it does have a touch of barrel distortion when fully wide. As well as the LCD It has an excellent OLED viewfinder that is much, much better than those typically found on Sony’s smaller cameras. It has Timecode in/out and genlock, all the XAVC-I and L codecs as well as MpegHD. There is a full suite of wifi, LAN and network functions for streaming, ftp and remote control as well as the ability to offload files from the cards to a USB drive or memory stick without a computer. It’s a modern camera designed for the modern news or documentary shooter and a big step up in terms of image quality from the PXW-X200 IMHO.

A full review and sample video will be coming in the very near future with lot’s more information.

Adobe still can’t get XAVC levels right!

I’m often asked at the various workshops I run why I don’t grade in Adobe Premiere. Here’s why – they can’t even get basic import levels right.

Below are two screen grabs. The first is from Adobe Premiere CC 2019 and shows an ungraded, as shot, HLG clip. Shot with a Sony Z280 (love that little camera). Note how the clip appears over grossly exposed with a nuclear looking sky and clipped snow, it doesn’t look nice. Also note that the waveform suggest the clips peak levels exceed 110%. Now I know for a fact that if you shoot HLG with any Sony camera white will never exceed 100%.

Adobe-HLG1c-1024x626 Adobe still can't get XAVC levels right!
Incorrect levels with an XAVC clip in Adobe Premier. Click on the image to view a larger version.

The second screen grab is from DaVinci Resolve and it shows the same clip. Note how in Resolve that although bright the clip certainly doesn’t look over exposed as it does in Premiere. Note also how the levels show by the waveform now no longer exceeds code value 869 (100% white is 940).  These are the correct and expected levels, this is how the clip is supposed to look. Not the utter nonsense that Adobe creates.

resolve-hlg1b-1024x626 Adobe still can't get XAVC levels right!
Same XAVC clip in Resolve and now the levels are correct. Click on the image to view a larger version.

Why can’t Adobe get this right. This problem has existed for ages and it really screws up your footage. If you are using S-Log and you try to add a LUT then things get even worse as the LUT expects the correct levels, not these totally incorrect levels.

Take the SDI or raw out from the camera and record a ProRes file on something like a Shogun while recording XAVC internally and the two files look totally different in Premiere but they look the same in Resolve. Come on Adobe – you should be doing better than this.

If they can’t even bring clips in at the correct levels, what hope is there of being able to get a decent grading output? I can make the XAVC clips look OK in Premiere but I have to bring the levels down to do this. I shouldn’t have to. I exposed it right when I shot it so I expect it to look right in my edit software.

ISO and EI – using the right terms makes what you are doing easier to understand.

ISO and EI are different things and have different meanings. I find that it really helps understand what you are doing if you use the terms correctly and understand exactly what each really means.

ISO is the measured sensitivity of film stock. There is no actual direct equivalent for electronic cameras as the camera manufacturer is free to determine what they believe is an acceptable noise level. So one camera with an ISO of 1000 may be a lot more or less sensitive than another camera rated at 1000 ISO, it all depends on how much noise the manufacturer things is acceptable for that particular camera.

Broadly speaking on an electronic camera ISO is the number you would enter in to a light meter to achieve the a normally exposed image. It is the nearest equivalent to a sensitivity rating, it isn’t an actual sensitivity rating, but it’s what you need to enter into a light meter if you want to set the exposure that way.

EI is the Exposure Index. For film this is the manufacturers recommended best setting for your light meter to get the best results following the standard developing process for the chosen film stock. It is often different from the films true sensitivity rating. For example Kodak 500T is a 500 ISO film stock that has an EI of 350 when shooting under tungsten light. In almost all situations you would use the EI and not the ISO.

On an electronic camera EI normally refers to an exposure rating that you have chosen to give the camera to get the optimum results for the type of scene you are shooting. ISO may give the median/average/typical exposure for the camera but often rating the camera at a different ISO can give better results depending on your preferences for noise or highlight/shadow range etc. If you find exposing a bit brighter helps your images then you are rating the camera slower (treating it as though it’s less sensitive) and you would enter your new lower sensitivity rating into your light meter and this would be the EI.

Keeping EI and ISO as two different things (because they are) helps you to understand what your camera is doing. ISO is the base or manufacturer sensitivity rating and in most (but not all) log or raw cameras you cannot change this.

EI is the equivalent sensitivity number that you may choose to use to offset the exposure away from the manufacturers rating.

If you freely interchange ISO and EI it’s very confusing for people as they don’t know whether you are referring to the base sensitivity rating or a sensitivity rating that is not the base sensitivity but actually some kind of offset.

If you have a camera with an ISO rating of 2000 and you say “I’m shooting at 800 EI” then it’s clear that you are using a 1.3 stop exposure offset. But if you just say “I’m shooting at 800 ISO” it is less clear as to exactly what you are doing. Have you somehow changed the cameras base sensitivity or are you using an offset? While the numbers used by EI and ISO are the same, the meaning of the terms ISO and EI are importantly different.

Learning to be a film maker? Don’t shoot short pretty videos – shoot documentaries.

Over the years I’ve met many well known high end cinematographers. Most of them are really no different to you or I. Most of them are passionate about their craft and almost always willing to chat about ideas or techniques. But one thing that at first surprised me  was how many of these high end movie makers cut their teeth shooting documentaries. I guess I had imagined them to have all been film school graduates that shot nothing but drama, but no, a very large percentage started out in the world of documentary production.
Documentary production is full of challenges. Location shooting, interviews, beauty shots, challenging lighting etc. But one of the big things with documentary production is that you very often don’t have a choice about what, where or when you shoot. You are faced with a scene or location needed for the story and you have to make it look good. So you have to think about how best to approach it, how to frame it, light it or how to use the available light in the best way.
A lot of todays aspiring film makers like to hone their skills by shooting beautiful people in beautiful locations when the light is at it’s best. These short beauty films very often do come out looking very nice. But, if you have a pretty girl, a pretty scene, and good light then really there is no excuse for it not to look good and the problem is you don’t learn much through doing this.
When you are shooting a typical TV documentary you will be faced with all kinds of locations, all kinds of people and the challenge is to make it all look good, no matter what your presented with. Having to take sometimes ugly scenes and make them look good you learn how to be creative. You have to think about camera angles, perhaps to hide something or to emphasise something important to the story the programme tells. And, like a feature film it is normally also story telling, most documentaries have a story with a beginning middle and end.
If you can master the art of documentary production it will give you a great set of skills that will serve you well elsewhere. If you move on from documentaries to drama, then when the director asks you to shoot a scene that takes place in a specific location you may well have already done something similar in a documentary so you may already have some ideas about how to light it, what focal lengths to use. Plus now you will probably have a more time to light and a much more control over the scene, so it should actually be easier.
 
In an ideal world I guess the best way to learn how to shoot movies is…. to shoot movies. But very often it’s hard to get the people, locations and good script that you need. So very often aspiring film makers will fall back on shooting 90 second vignettes of pretty people in pretty places as it’s easy and simple to do.
But instead I would suggest that you would be much better off shooting a documentary. Perhaps about something that happened near where you live or an issue you are interested in.
Go out and shoot  documentaries in less than perfect locations with all the challenges they present. I bet the resulting videos won’t look nearly as perfectly pretty as all those slow-mo pretty girl on a beach/forest/field of flowers videos. But it will teach you how to deal with different types locations, people, lighting, weather and many of the other things that can be challenges when shooting features. It will make you a better camera operator. Making something that’s already pretty look pretty – that’s easy. Making what would otherwise be an un-interesting living room, factory or city street look interesting, that’s a much tougher challenge that will help bring out the creativity in you.

Noise, ISO, Gain, S-Log2 v S-Log3 and exposure.

Even though I have written about these many times before the message still just doesn’t seem to be getting through to people.

Since the dawn of photography and video the only way to really change the signal to noise ratio and ultimately how noisy the pictures are is by changing how much light you put onto the sensor.

Gain, gamma, log, raw, etc etc only have a minimal effect on the signal to noise ratio. Modern cameras do admittedly employ a lot of noise reduction processes to help combat high noise levels, but these come at a price. Typically they soften the image or introduce artefacts such as banding, smear or edge tearing. So you always want to start off with the best possible image from the sensor with the least possible noise and the only way to achieve that is through good exposure – putting the optimum amount of light onto the sensor.

ISO is so confusing:

But just to confuse things the use of ISO to rate an electronic cameras sensitivity has become normal. But the problem is that most people have no clue about what this really means. On an electronic camera ISO is NOT a sensitivity measurement, it is nothing more than a number that you can put into an external light meter to allow you to use that light meter to obtain settings for the shutter speed and aperture that will give you the camera manufacturers suggest optimum exposure. That’s it – and that is very different to sensitivity.

Lets take Sony’s FS7 as an example (most other cameras behave in a very similar way).

If you set the FS7 up at 0dB gain, rec-709, it will have an exposure rating of 800 ISO. Use a light meter to expose with the meters ISO dial set to 800. Lets say the light meter says set the aperture to f8. When you do this the image is correctly exposed, looks good (well as good as 709 gets at least) and for most people has a perfectly acceptable amount of noise.

Now switch the camera to S-Log2 or S-Log3. With the camera still set to 0dB the ISO rating changes to 2000 which give the impression that the camera may have become more sensitive. But did we change the sensor? No.  Have we added any more gain? No, we have not, the camera is still at 0dB. But if you now expose at the recommended levels, after you have done your grading and you grade to levels similar to 709 the pictures will look quite a lot noisier than pictures shot using Rec-709.

So what’s going on?

If you now go back to the light meter to expose the very same scene, you turn the ISO dial on the light meter from 800 to 2000 ISO and the light meter will tell you to now set the aperture to f13 (approx). So starting at the f8 you had for 800 ISO, you close the aperture on the camera by 1.3 stops to f13 and you will have the “correct” exposure.

BUT: now you are putting 1.3 stops less light on to the sensor so the signal coming from the sensor is reduced by 9dB and as a result the sensor noise that is always there and never really changes is much more noticeable. As a result compared to 709 the graded S-Log looks noisy and it looks noisier by the equivalent of 9dB. This is not because you have changed the cameras sensitivity or changed because you have changed the amount of camera gain but because compared to when you shoot in 709 the sensor is being under exposed and as a result it is outputting a signal 9dB lower. So in post production when you grade or add a LUT you have to add 9dB of gain to get the same brightness as the original direct rec-709 recording and as well as making the desirable image brighter it also makes the noise 9dB higher (unless you do some very fancy noise reduction work in post).

So what do you do?

It’s common simply to open the aperture back up again, typically by 1.5 stops so that after post production grading the S-log looks no more noisy than the 709 from the FS7 – Because in reality the FS7’s sensor works best for most people when rated at the equivalent of 800 ISO rather than 2000 – probably because it’s real sensitivity is 800 ISO.

When you think about it, when you shoot with Rec-709 or some other gamma that won’t be graded it’s important that it looks good right out of the camera. So the camera manufacturer will ensure that the rec-709 noise and grain v sensitivity settings are optimum – so this is probably the optimum ISO rating for the camera in terms of noise, grain and sensitivity.

So don’t be fooled into thinking that the FS7 is more sensitive when shooting with log, because it isn’t. The only reason the ISO rating goes up as it does is so that if you were using a light meter it would make you put less light onto the sensor which then allows the sensor to handle a brighter highlight range. But of course if you put less light onto the sensor the sensor won’t be able to see so far into the shadows and the picture may be noisy which limits still further the use of any shadow information. So it’s a trade-off, more highlights but less shadows and more noise. But the sensitivity is actually the same. Its’s an exposure change not a sensitivity change.

So then we get into the S-Log2 or S-Log3 debate.

First of all lets just be absolutely clear that both have exactly the same highlight and shadow ranges. Both go to +6 stops and -8 stops, there is no difference in that regard. Period.

And lets also be very clear that both have exactly the same signal to noise ratios. S-log3 is NOT noisier than S-log2. S-log 3 records some of the mid range using higher code values than S-Log2 and before you grade it that can sometimes make it appear like it’s noisier, but the reality is, it is not noisier.  Just like the differing ISO ratings for different gamma curves, this isn’t a sensitivity change, it’s just different code values being used. See this article if you want the hard proof: http://www.xdcam-user.com/2014/03/understanding-sonys-slog3-it-isnt-really-noisy/

Don’t forget when you shoot with log you will be grading the image. So you will be adjusting the brightness of the image. If you grade S-Log2 and S-Log3 to the same brightness levels the cumulative gain (the gain added in camera and the gain added in post) ends up the same. So it doesn’t matter which you use in low light the final image, assuming a like for like grade will have the same amount of noise.

For 8 bit records S-Log2 has different benefits.

S-Log2 was designed from the outset for recording 14 stops with an electronic video camera. So it makes use of the cameras full recording range. S-Log3 is based on an old film log curve (cineon) designed to transfer 16 stops or more to a digital intermediate. So when the camera only has a 14 stop sensor you waste a large part of the available recording range. On a 10 bit camera this doesn’t make much difference. But on a 8 bit camera where you are already very limited with the number of tonal values you can record it isn’t ideal and as a result S-Log2 is often a better choice.

But if I shoot raw it’s all going to be so much better – isn’t it?

Yes, no, maybe…. For a start there are lot’s of different types of raw. There is linear raw, log raw, 10 bit log raw, 12 bit linear, 16 bit linear and they are all quite different.

But they are all limited by what the sensor can see and how noisy the sensor is. So raw won’t give you less noise (it might give different looking noise). Raw won’t give you a bigger dynamic range so it won’t allow you to capture deeper or brighter highlights.

But what raw does normally is to give you more data and normally less compression than the cameras internal recordings. In the case of Sony’s FS5 the internal UHD recordings are 8 bit and highly compressed while the raw output is 12 bit, that’s a 4 fold increase in the amount of tonal values. You can record the 12bit raw using uncompressed cDNG or Apples new ProResRaw codec which doesn’t introduce any appreciable compression artefacts and as a result the footage is much more flexible in post production. Go up to the Sony Venice, F5 or F55 cameras and you have 16 bit raw and X-OCN (which behaves exactly like raw) which has an absolutely incredible range of tonal values and is a real pleasure to work with in post production. But even with the Venice camera the raw does not have more dynamic range than the log. However because there are far more tonal values in the raw and X-OCN you can do more with it and it will hold up much better to aggressive grading.

It’s all about how you expose.

At the end of the day with all of these camera and formats how you expose is the limiting factor. A badly exposed Sony Venice probably won’t end up looking anywhere near as good as a well exposed FS7. A badly exposed FS7 won’t look as good as a well exposed FS5. No camera looks good when it isn’t exposed well.

Exposure isn’t brightness. You can add gain to make a picture brighter, you can also change the gamma curve to change how bright it is.  But these are not exposure changes. Exposure is all about putting the optimum amount of light onto the sensor. Enough light to produce a signal from the sensor that will overcome the sensors noise. But also not so much light that the sensor overloads. That’s what good exposure is. Fiddling around with gamma curves and gain settings will only every make a relatively small difference to noise levels compared to good exposure. There’s just no substitute for faster lenses, reflectors or actually adding light if you want clean images.

And don’t be fooled by ISO ratings. They don’t tell you how noisy the picture is going to be, they don’t tell you what the sensitivity is or even if it’s actually changing. All it tells you is what to set a light meter to.

Norway 2019 Aurora Tours Filling Up Fast.

In February 2019 I am running 2 Aurora hunting trips to the north of Norway. One of these has just sold out so that means that  places are now only available on the first tour.

A7-first-night1-1024x684 Norway 2019 Aurora Tours Filling Up Fast.
Captured on the first night at the cabins in 2018.

These are very different to the normal Aurora hunting trips to a big city. We start in the town of Alta in Northern Norway, staying in a nice hotel close to the amazing looking Northern Lights Cathedral. From there we travel inland to the capital town of the Sami people – Karasjok.

As we get near to Karasjok we exchange our mini-bus for snow scooters and sleighs and journey way off the beaten track, up above the tree line and across frozen lakes to a small lodge used by cross country skiers and dog sled teams. This group of cabins becomes our base to explore the Finnmarksvidda for 4 days as well as being a near perfect location for watching, photographing and filming the Northern Lights.

-Jan-Helmer-Olsen-Ravnastua_2017-0011-1024x576 Norway 2019 Aurora Tours Filling Up Fast.
We always try to get up onto the plateaux at some point. This view taken from a drone shows how desolate yet beautiful it is. Nothing man made from horizon to horizon.

It is stunningly beautiful around the cabins, it’s also amazingly peaceful and quiet. We are looked after by a couple of Sami people who cook meals for us, take us ice fishing and help us explore this spectacular and unspoilt winter wilderness.

If you want to know more please take a look at the main page for the tours: http://www.xdcam-user.com/northern-lights-expeditions-to-norway/

 

Camera setup, reviews, tutorials and information for pro camcorder users from Alister Chapman.