Author Archives: geoff

Science or Art?

I spent an interesting evening at Antwerp University last week, I’d gone to do a short presentation on HDR & WCG.

The main presenter was a scientist who was comparing raw with log and “baked in”, he went on to “Prove” that you can grade “baked in”just as well as you can raw, in fact it could be better he implied.

Well excuse me! that may be true in a theoretical world where we have infinite bit depth but in a real world situation that just isn’t true. 
The limitations of the formats we use will cause damage to the image unless we are very careful.
I tried to point out that raw was always better in a real world because the camera output required processing and the processing we could do in camera was limited compared to what we could do in post. The cameras inbuilt processing was limited both by size and heat generation.
Apparently not from a scientific point of view, he could prove I was wrong, here was the proof on the whiteboard.

Well excuse me but I make pictures not numbers on a whiteboard and I can clearly see the difference. We briefly touched on compression and “lossless” compression, I gave up, the argument would have taken the whole evening.

2 stories for background to my point of view…

I was shooting test footage for Kodak at their plant in Chalon France, I had my entire commercials crew with me and we were looking at 2 prototype films compared to 5294 and Agfa XTR250. The reason we were including the Agfa was that it was starting to eat into their sales and they wanted an emulsion to beat it. I was a heavy user of XTR 250 as were the 11 other DP’s shooting tests worldwide.

One of the prototypes was just awful but one of them was looking good. I used the XTR because it had much greater latitude than the ’93 which was popular at the time, a lot more latitude and it fitted my lighting style.
We set up a final scene to stress the stocks which involved a model moving through light and dark in a Chateau and tested highlight colour separation.
Looking at the results projected it was very quickly clear that ’93 just couldn’t cope but that the good prototype had better highlight and shadow detail than the Agfa and more accurate reproduction of the very saturated red dress the model was wearing, it also coped really well with the subtle highlight colours.
After I’d said all that the Kodak guys said “so you’ll switch to this when we introduce it” my reply shocked them, “no, it’s not as pretty”.
My job is not to make accurate pictures it’s to make pretty ones…

Next story, years ago I was at NAB and it was all getting to me so I escaped to the sports bar in the Hilton next door (it was on you right as soon as you left the convention center) as usual it was full of other escapees. Also as usual I got chatting to a guy at the bar, I didn’t know who he was because his badge wasn’t showing, he was just Ray.
We had a great conversation about compression and he obviously knew what he was talking about. We talked about lossless and visually lossless. The first being what it advertised and the second depending on the judgement of the mathematicians who wrote the algorithms used.
I took away the clear point that anything over 3 to 1 was not true lossless and therefore depended on someones opinion.
As we were leaving his badge appeared, yes, his name was Ray, Ray DOLBY! I kinda thought he knew what he was talking about 🙂

Now, is someone who is a mathematician/scientist as aware of what makes a good picture as I am? why would anyone make that assumption? they don’t assume I know as much about maths as they do, how would they react if I came along and told them their algorithms were wrong and altered a few lines of code?

Treat me with the same respect I treat them, I accept they know their business better than I do, maybe they should accept that I know more about how to make a good image than they do…

If you’ve got no ambition why bother?

I’ve been involved in another of those wonderful Twitter/Facebook threads about exposure and again I keep getting told that you don’t need a meter and using a waveform is far more accurate.

Well yeah, if you have absolutely no ambition and are happy shooting single camera on corporates and weddings with the odd bit of news thrown in but if you have any ambition at all you’ll need to learn how to use a meter!

You may never get the chance to go for “the big one” but I promise you, if you don’t know how to use a meter you will fail if you ever do get the chance.

How do you recce a big interior location where you will have to enhance the available light without a meter?

How do you work across multiple locations/sets and match everything if you don’t have a meter?

How do you prelight a set or location if you don’t have and understand a meter.

Once you move beyond the perfectly good work in single camera you will not be able to have a camera and a monitor with you at all times. It’s just too bloody expensive.

My personal record for pre-lighting, recceíng or shooting, is seven simultaneously in a day. How do you do that with a camera and a monitor? ONLY a meter will work.

To use a meter properly you have to learn how meters work, you have to learn how visualise how scenes will appear on a monitor or screen. You need to understand what brightness levels need to fall where.

I use both spot and incident meters, the incident to get an overall level reading and the spot to look at individual areas. You need to know where skintones will fall, what the key to fill ratio you like is. You need to be able to measure that ratio. 

As we move to HDR you need to use a meter even more. There will be a temptation to use all that extra range but that will only lead to pain, as is clear with some of the HDR series currently on Netflix.

You can let specular highlights go but you need to be aware of areas that may well hold detail in HDR but regardless of this they’ll be too bright and distract from the main scene. A meter will help you hugely with this.

On the other hand you can ignore this and go on with your single camera and monitor and in later life look back and wonder why you never moved on…

Personal comments on the 2018 CML camera evaluations

I want to stress that these are purely personal impressions and that you should check out the raw files at  https:/cmltests.net  and also get your hands on a camera to see how it feels for you before making any decisions.
When we were shooting we used an Odyssey and a Canon 24″ monitor to see what we were doing.

In all cases the EI mentioned is what was required to give a “correct” & neutral picture in Resolve with no tweaking. Highlight response is the point where the small grey square within the white square on the CML chart disappears.  Shadow level is where I find the noise to be unacceptable beyond this point.

Alexa Mini: Ours came with open gate and raw licenses and an Amira V/F, it fired up quickly and had very clear and easy menus.

I would rate this camera at an EI of 1000 with a highlight latiude of 5 stops but the shadows only give 2 stops. I’d set the camera too EI 800 and my meter to EI 320-400 to get the best compromise between highlights and noise. DR beyond the charts is 7 stops.
Note:- Bear in mind that yellow clips a little before any other colour.

BMD Ursa MP: We didn’t have the V/F for this and used the swing out monitor that is built in, it fired up quickly and had a very clear and easy to use menu.

I would rate this camera at EI 800 with a highlight latitude of 3.5 stops and a shadow level of 2 stops. I’d set the camera to EI 800 and my meter to EI 500 to get the best results from this camera. DR beyond charts is 5.5 stops.
Note: Yellow again clips earlier than other colours.

Canon C200: We used the touch screen V/F that comes with the camera, it fired up quickly but the menus do take some getting used to! There’s a lot there but it’s not all easy to find.

I would rate this camera at EI 800 with a highlight latitude of 3.5 stops and shadows of 2.5 stops.
I’d set the camera to EI 800 and my meter to EI 500 to get the best results from this camera. DR is 6 stops beyond the charts.
Note: Once again yellow clips earlier than other colours.

Canon C700 FF 6K to 4K in camera: We had the full V/F on this and it’s a lovely one 🙂 the menu system was a little easier to use. Recording to XF-AVC internally was easy but recording the RAW output to 6K and 4K relied on using an external Codex recorder which results in a camera that is too big and ungainly to use. No issues with startup time. We had all the usual issues licensing the Codex reader, it shouldn’t be this hard. I think Canon really missed a trick here by not releasing a FF camera that included the raw recording from the C200.

I would rate the camera at EI 500 with a highlight latitude of 3.5 stops and shadows of 3.5 stops.
DR is 7 stops beyond the charts.
I’d set the camera to 800 and my meter to 500 to get the best from this camera.
Note: Again yellow clips early.

Fuji X-H1: I’m not going to comment on the V/F, it’s a DSLR…same for the menus 🙂 lots of them but if you’re a DSLR user they make sense! we used flog recording at 200Mbps the best it can do and although I’m not impressed with the amount of sharpening and NR that was present in the standard setting it is possible to reduce these considerably and I’m experimenting with this at the moment.

I would rate this camera at EI 1000 with a highlight latitude of 3 stops and shadow limit of 2 stops (see notes). DR 5 stops beyond the charts.
I’d set the camera to 800 and my meter to 500 to get the best from this camera.
Note: this camera clips hard in the yellow and red well below the 3 stop point so be careful.

Kinefinity Mavo: it fires up pretty quickly but some of the menus are very confusing, separate settings for EI and ISO?? It’s not ready for general consumption yet, they need to get their post workflow sorted. When they do it could be a very good camera.

I would rate the camera at EI 800 with a highlight latitude of 4 stops, I’m not sure what the shadow latitude is because of post issues but it looks like it could be very good indeed.
Note: I haven’t been able to do a full and good assessment of this camera or the Terra because of the post workflow issues.

Kodak 5219: Checking on a few things about the scans before I post but by far the best highlight latitude of anything we tested, about 6 stops, but that’s where our tests ran out, it could be more. I’d rate it at EI 320 to get the best from it but that’s what I’ve found with all film stocks. They respond well to 2/3rds over.

Panasonic Varicam:  I asked for a Pure and got a V35 with a Codex recorder added to the back, nightmare of a huge ungainly camera, the Pure solves this. A clear and sensible menu system. Once again the Codex system proved difficult. It may be wonderful with a specialist DIT but for an ordinary DP it’s a pain.

I’d rate this camera at EI 800 with a highlight limit of 4 stops and shadows of 2 stops. Thats 6 stops beyond the chart DR.
I’d set the camera at 800 and my meter at 400 to get the best from this camera.

Panasonic EVA: We recorded this on an Inferno in ProRes raw so you’re going to have to wait! what we can see looks good but what we see that is bad could be due to the post process.

RED Gemini: We used this camera with the 5″ V/F mounted on the front and it was easy to use and setup.
I’d rate this camera at EI 800 with highlight latitude of 3.5 stops and shadow latitude of 3 stops. That’s 6.5 stops beyond the charts DR.
I’d set both the camera and my meter at EI 800 to get the best from this camera
Note: The red chip  at 25% clips as a hard orange at half a stop below maximum latitude so be careful with reds with this camera, overall I really like it.

RED Monstro: We had to stop for lunch to black shade this camera, it is very much the RED camera look that I don’t like.
I would rate the camera at EI 500 and highlights clip at 2.5 stops with shadows going at minus 2.5 stops.
That gives 5 stops beyond the DR of the charts.
Note: Reds and Yellow clip hard at plus 2 stops so the overall latitude is really 4.5 stops unless you’re very careful. I’ve had people say I could get better results in RedCine but this is a test on a level playing field.

Sony Venice: It fires up quickly, changes modes quickly, has an easy menu, is compact and balanced.
I’d rate this camera at EI 400 with a latitude in the highlights of 4 stops and 2.5 in the shadows.
this is 6.5 stops beyond the DR of the charts.
I’d rate both the camera and my meter at EI 400 to get the best from this camera.
Note: The highlights clip slowly and smoothly and the colour is not that “Sony Look” it also has the most consistent colour across the exposure range.

Finally, check out the raw files if you care about images http://cmltests.net/Digital-Cinematography-Camera-Evaluations-2018.html

What do I want in a camera?

Not a lot actually.

I want to be able to use it without a caravan of kit and crew.

I want to be able to take it out of the box and be able to shoot within 5 seconds.

I want preset colour temperatures to be accurate.

I want the indicated ISO to be accurate.

I want a camera that has a simple recording system that doesn’t require contacting the NSA or GCHQ to get my rushes!

I want a camera that doesn’t veer from magenta to green or vice versa with exposure.

I want a camera that doesn’t do weird things at the extremities of exposure at either end of the scale

I want to load it into a post program and get good images without having to fiddle around.

ACEScct should do this, if the camera is good it will give me a “correct” image at between 22 and 28 on the offset dial in Resolve.

That shouldn’t be hard.

The only problem is that with a few exceptions it seems to be bloody near impossible!

Price has no reflection on the issues.

I find myself getting more and more angry with manufacturers who keep on making the same mistakes year after year.

I’m pausing the camera evaluations to go off on my bike and cycle along canal sides through beautiful countryside and watch ducks and swans and storks and geese and wildlife generally.

RAW camera files available now

I’ve just setup and new CML site that is linked to the main one.
The new site is specifically for the camera raw files from the Digital Cinematography Evaluation sessions.

At the moment raw files from the 2017 sessions are available, once we have finished the 2018 in a month or so the new files will be uploaded and these will be removed.

The new system is insanely fast with multiple SSD’s and also multiple processors.

I would like to point out that this is a site for grownups, if you don’t know what you’re doing please don’t waste your time.

The files are large, very large, averaging 8GB per file.

I will not be answering queries about these files unless the query is from a CML subscriber.

https://www.cmltests.net

“Filmlook” or TV standard?

I’ve been asking for peoples opinions about what needs to be included in the next camera evaluations but the answers are highly contradictory.

It comes back to the old which do you prefer, the look of film or the look of TV. The majority of people will say film.  Or at least digital images which emulate the look of film.

They then insist that camera evaluations are done using TV charts and to TV levels.

Given that the original rushes will be made available and also 16 bit EXR files the only people looking at the processed results are either those who can’t use the original files for some reason or other and those who can’t be arsed.

The second group can… The first group don’t need to look at something designed to make the cameras look like TV cameras. They need to know that a workflow to get the best film look has been followed. Let’s not get into the pointless argument of what the film or TV looks are, we all know what we mean by those terms.

We then get to the question of where do we put the levels, there are all kinds of answers varying from 30% to 50% but lets make this clear, I’m working within ACES so log levels on a waveform don’t apply. Once an IDT has been applied and we are in ACES space we are working with an environment that has an inherent toe and shoulder and straight middle gamma.

So I’ve gone back to basics. All the years I sot commercials on film and scanned the neg into a video or later digital environment I used a simple reference. The Kodak Gray Scale Plus. They tell you where to put the mid grey part of the chart in very simple terms. I’m looking at the back of one now and it clearly says 122, 122, 122 in 8 bit values. In the past I’ve used 128, 128, 128 and I’ve had a lot of grief about it. It turns out I was bloody close to the recommended Kodak level and far closer than any of the corrections I was being given.

I will not use TV limited charts.

I will try and produce evaluations that look more like the best film that you have seen and less like NHK.

Information or Knowledge?

It’s becoming clear to me that there is a huge confusion between information and knowledge.

Whilst I love the net it is creating a major problem in that by making so much information available so easily a lot of people think that by looking up information on the net they can “know” something.

This is just not true, truly “knowing”something implies understanding and being able to balance one source of information against other source of information and use experience to come to a reasoned and comprehensive understanding of an issue.

It is often possible to get information on the net that “proves” a point of view when in fact on closer examination and filtered through experience it actually proves the opposite.

When I’m teaching workshops and also posting on the net I’m often asked for a reference for what I’m saying. The problem here is what I am saying is based upon 50 years of experience. I’m sure some of that experience is based upon things I have read or seen along the way but specific references? get real! Generally if anyone can be bothered to research deeply enough they can find an actual reference 🙂

The biggest differences between information and knowledge are speed, depth and breadth. I don’t need to look up what the foot candle or lux level of lighting is needed to get a T stop of 8 with EI speed 400 and a shutter of 180, I just know it. I also understand the implications and variables that come from that aperture and shutter angle and what possibilities there are. When I say that I generally expose camera X at an EI of 250 it’s not arbitrary or the result of looking it up on the net. It’s from years of experience and the knowledge of balancing what is best for shooting and what is best for post along with dozens of other variables.

There is no shortcut, it takes time to assimilate enough information and experience to truly have knowledge of it.

Not acknowledging this will lead to incorrect assumptions, embarrassment and pain.

The next camera evaluations

In preparation for the next round of camera evaluations I asked for comments and got a lot regarding the type of charts I was using.

I’ve been thinking a lot about this and I think we may have it all backwards.

Conventional rec 709 TV has a DR of at most 6 stops and if the charts are slavishly adhered to only 5 stops.

However, once the knees and hypergammas etc are taken into account we are actually working with 8 stops at least.

10 bit log-c will contain about 11.5 stops of DR and that’s more than the best available domestically HDR sets can handle.

Of course that limitation isn’t the camera, it’s the record format and that’s why I record RAW for these tests with a few odd exceptions that are forced on me like rendering 6K to 4K before recording.

So what are the tests trying to do?

I think that we, or I, have lost focus on this.

The tests are to find out what the usable DR of the cameras is.
To establish where the highlights actually begin to clip.
To see what colour distortions appear with exposure change.
To see if there are motion artifacts created by the cameras.
To check what happens to skintone with the different cameras and different lighting.
I acknowledge that I can’t check all lighting and camera combinations, although this would be a really useful experiment.

This is why I created the stress test chart, it’s not designed to show how a camera reacts to rec 709 conditions, it’s designed to see how far a camera can be pushed until it breaks.

THAT is what I’m interested in, it’s the kind of information that will affect how I shoot and what I use.

Just as ACES is designed to work regardless of output space, that can be changed later, so the CML tests will be conducted regardless of any “Standards”. We will try and establish the limitations of the cameras.
Of course some of you will only ever see those results within the limitations of a 709 or sRGB environment. They will at least show you what happens within that environment.

For those who want more I will make available both EXR’s in 16 bit ACES and, eventually, the original camera files.

I am now working out how to get the most information out of these evaluations. Part of this will be using a “standard” tungsten light source, the old fashioned kind that creates light by burning something 🙂 It will also involve charts lit at different levels within the one shot.
Which charts is another matter!
I’m leaning towards a CML stress Test and a Macbeth on either side of the frame, one side lit “normally” and one side 3 stops over. In the middle will be a Kodak grey scale plus card as this has been my reference for a very long time. A movement test will be below the Kodak chart. If I can get a small CDM chart then I will probably squeeze it in below the Kodak chart just for the traditionalists. Oh and a CamBelles chart will feature somewhere 🙂

I will also try and do some comparisons between faces lit with tungsten and LED light. This will include the DSC VFX chart.

Next Camera Evaluations – request for comments

First, my apologies for cross posting, but if I can’t break my own rules…I’m also posting on Cinerant.

The next camera evaluations are shooting in three weeks and I’ve been thinking about how to change them from previous ones, bearing in mind comments I’ve received.

I’m going to try to move away from marking =/- on the charts, it will be purely stop and shutter angle for this test.

I will light to 200fc and set the cameras to the manufacturers recommended EI.

We will shoot from T1.5 to T 22 at 180 degrees and then T22 at 90 & 45 degree shutter.

The tests will be shot both tungsten and LED daylight. Tungsten being the most “accurate” source I can use. I’d love to take the tests to Australia to shoot across a window of 11 am to 1pm across the weeks it would take to shoot the tests in real daylight! The LED’s will be the most commonly used and should show what happens in a “real-world” environment.

The evaluations will be available to download as EXR’s in ACES space from the ODN, and hopefully, depending on cost and support, I’ll also make some of the original camera files available. I had intended to do this but we lost a number of sponsors this year and may not be able to afford it.

I will also upload QT files to Vimeo, these will be UHD and 422, I’ll let them convert them to H264, and also H264 directly to YouTube.

The compiled files that I upload will be all matched at 18% grey, matching only the green level as I don’t intend to colour correct them in any way. Everything will go through ACES with standard IDT’s and appropriate ODT’s.

This time I will make observations as to which EI I think the cameras should be exposed at to get the best images, this will be basically based around noise levels.

So if you set the camera to an EI of 800 but the noise is better at 500 I’ll say so, I’ll also upload a LUT that adjust for you setting the camera to 800 and your meter to 500. This will be a LUT in 2 forms, one that is “naked” and just needs to be dropped into the ACES pipeline in Resolve and the other will include the appropriate IDT’s and ODT’s to “correct” the image on 709 monitors on the floor.

I guess I’m going back to the days when I published GRR’s for various film stocks ?

OK, beat me up now.