I have just uploaded a brief guide to the EX gamma curves to youtube.

YouTube - XDCAM EX Gamma Curves and Knee, what they do and which ones to use. (http://www.youtube.com/watch?v=s-9aaK2gefg&fmt=18)

You can find all my guides on this page:

XDCAM-USER.com How to Videos (http://www.xdcam-user.com/?page_id=13)

Thanks for that Alister.

Very very well done.

John

Excellent job Alister! Very helpful.

Thanks

Jamie

Thanks, Alister. Very clearly explained.

It is worth noting where the various STD gammas come from though. Don't discount them. For example STD gamma 4 is 'BBC' gamma with an initial gain of 4.0x and was designed for post grading before all these new fangled cine gammas came in. It gives you quite a bit of range to work with, albeit without the smooth highlight rolloff of the cines.

Regarding cinegamma 2 I would also point out that although it gives legal levels, would you really leave your video untouched using this gamma setting? Probably not, so you might as well use the other gammas that give you the full tonal range.

One last thing, regarding Cines 3 and 4. I'm not sure that they actually have less highlight handling capability as such than 1 and 2. They seem to cram the same amount of overall contrast into the same amount of tonal range, but tend to put the emphasis on certain areas. So the highlight regions get less tonal range rather than less overall contrast (black to peak white detail) contrast range. Could be wrong, but thats how I'm reading the cine curves. Overall Cines 3 and 4 are still cramming 400% overload into 100% signal. If they were capturing less contrast range then at their peak white capability they would be capturing, for example off the top of my head, 300% input for 100% output or 200% input for 100% output.

But I'm not an engineer so... Would this be in the ball park?

Excellent tutorial. The EX community is grateful for your production.

Great job Alllister. Thanks for taking the time to do this. Very well done.

Your reading of the curves Simon is correct. I struggled with the appropriate, simple words to describe the differences with the way the CG's handle highlights. I believe the highlights in CG's 3 and 4 are not as well handled as in CG1 due to the extra highlight compression, hence the words chosen.

I could have gone on to state where each of the standard gammas originates, but for most people watching a clip at this level it would probably be fairly meaningless. What most people want to know is what difference does it make to the picture, not whether they are variations on 701, 601 etc.

I do state that the cinegammas are designed to be graded in the video, however it's not essential, just personal choice.

These video's are simple 4 minute guides that I am making available for free. I'm not going to spend hours going into every last detail, for example I don't touch on knee slope or knee sat. I hope they will act as a starting point for those that currently have no idea what some of these tools do.

Sorry Alister, my post was really meant as an supplementary set of notes to your video, so I apologise if I came over in the wrong way. I wasn't suggesting that that sort of detail should have been included as I realise that you needed to keep things straightforward and simple. :-)

Thanks Alistair,

I'm new to the EX3 coming from JVC HD101, and I found your contribution most helpful.

regards
Ian Skurri

Thanks Alistair,
I looked forward to these guides you do.

Have a question.
Does the F350 have the same Cinegamma cures.

Thanks

PMW-EX1/EX3 has the same CineGammas as the PDW-F350/F330/F335/355. Cinegammas 1 and 2 are the same as the Hypergammas HG4 and HG2 as found on the PDW-700 and F900R etc.

CINE1 : Same as the HyperGamma HG4
CINE2 : Same as the HyperGamma HG2
CINE3 : Independent setting for EX1/EX3
CINE4 : Independent setting for EX1/EX3

PDW-700 has HyperGamma (Ver1.2 or higher) such as,

HG1 : 325% D-range is compressed to 100%
HG2 : 460% D-range is compressed to 100%
HG3 : 325% D-range is compressed to 109%
HG4 : 460% D-range is compressed to 109%

Thats interesting that the 700 is only compressing a 480% overload. In that case there should be a lot of scope for the Digital Praxis curves that could be used in the F800 since the chips should be capable of a 600% overload.

On the 700 you can use a combination of standard gamma, knee and DCC to get 600%. DCC can be forced on in the menus and in effect you get a double knee.

Those figures did surprise me as I know when the HyperGammas are used the DCC gets taken over by the HG's and DCC can be set to operate at 600%

I have played with the knee/fixed DCC combo a bit but didn't like the look. Perhaps I need to re-visit.

Awesome video Al!!

Hi there,

I wouldn't really imply to leave knee on by default, even if the point is high. Some shots won't exceed the dynamic range that calls for knee. The price of knee is highlight contrast reduction. And I prefer to avoid any hint of the bigger price for faces, pasty skin.

The Knee is on by default from the factory, what's worse is the factory default is auto, so you have no control whatsoever. For most people the knee will bring more advantages than disadvantages.

The knee set at 85 should have no significant effect on skin and flesh tones unless you are overexposing or have a lot of specular highlights in which case it should help.

I would never use DCC. Too much like auto focus etc. Contrary to how it is often portrayed the DCC option doesn't always give you better highlight information. If the DCC decides that the highlights are not important it will free up the tonal range for the other sections of the picture and you end up with more blown highlights.

But yes you should be able to get 600% by adjusting the knee slope in combination with the knee point. But personally I'd leave the DCC well alone.

Right you are, Auto Knee is Sony's default not only for EX but also for their full size cams. Is it so for your 700 also? One of the first things I do after factory reset when painting is turn Knee off. When I see a shot with illegal or lost detail in highlights then I'll play with it. Most of my stuff these days I don't know where it will end up so I have to observe the common denominator for levels.

On the PDW-700 the DCC is on the Bar/Camera/Cam+DCC switch so you can turn it off. I'm sure many camera ops just flick the switch all the way over to Cam+DCC. If you have the knee on as well the results can be nasty.

Very good work and a very nice contribution to our community. Thank you for sharing your knowledge Alister.