Gamma curves in F3 flat on top?
 

I grabbed F3 Test Ramp from the Service Menu, and apply all the gammas listed in PP. I find all of them have the top end flatten out almost like some sort of clipping.
Aren't they supposed to be curved, not flat?
Can anybody shed some light about this?
Thanks.

Re: Gamma curves in F3 flat on top?
 

Here are the CGs, also FCP's own ramp for comparison.

Re: Gamma curves in F3 flat on top?
 

Can you please post the button/switch combination to reach the F3 service menus?

I remember it was a bit convoluted to get to the F900 and even the EX service menus and it doesn't seem to be posted anywhere on the net that I can find.

Be aware that we are all total professionals on this forum so advice towards precaution in using these will not be necessary as we all pretty much understand the downsides of fiddling with service menus too much.

A saw pattern is an invaluable tool for those of us who are experimenting or custom designing gamma curves for our cameras.

Thanks

Re: Gamma curves in F3 flat on top?
 

FCP being from the Apple Alternate Universe seems to default to clipping everything a 100%, not 109%, as I understand it. Apple have never played nice with gamma curves apparently. Don't use them myself, so I'm just repeating others observations.

Re: Gamma curves in F3 flat on top?
 

I read around here and found posting how to enter service menu is forbidden here, so ridiculous IMO as we are all camera owners and professionals. I asked before myself and no one would give me too..so I fiddle and search around and found the procedure myself.
A hint: It's the same as in EX1R.

Re: Gamma curves in F3 flat on top?
 

David, as we can see in FCP Ramp above is not clipped at all.
Also we can see in CG curves it doesnt even reach 90% but they are all flat out on top.

I'm suspicious that the flat tops are deliberately made to make F3 lose about a stop on the highlights.
Hasn't it made like this, no one will buy S-Log.

Re: Gamma curves in F3 flat on top?
 

Have not tested this myself but looking at those plots my guess is that the internal saw generator only goes up to 100% and when the CG's are applied to it the top end compression is resulting in a reduced output. So, your seeing the general shape of the curves, but not the correct output levels.

Testing a camera with a wedge chart or simple gradient generated on a computer screen and adjusting exposure up and down to examine the low/mid/highlights will show the curves do go to 109 and behave much more as you would expect. I don't think the saw is telling you anything useful, much better to test by shooting an exposure chart.

Re: Gamma curves in F3 flat on top?
 

David: your using a gamma curve every time you use a video cameras. Every camera has a gamma curve, it's just on some you can select more than the default.

Monitors have a gamma curve. To get a sensible looking image the camera must have the opposite gamma to the monitor so when the two gammas are added together we get a true representation of what was shot. For HD the normal gamma is Rec-709 which is the EX and F3's default gamma.

Re: Gamma curves in F3 flat on top?
 

Really? Of course they do, I meant I don't use Macs :) Assuming I don't understand gamma curves after I pointed you in the right direction to correct your S-Log article? Short memory :)

Re: Gamma curves in F3 flat on top?
 

Sorry David, yes short memory, I get involved in so many discussions with so many people that I don't always remember who said what and when plus I completely miss-read your post. My S-log article was not incorrect, just my examples were not well thought out and your input was most welcome.


Mac's do not clip everything at 100%. If you had seen my posts elsewhere about this very subject you would appreciate that the handling of files that go over 100% is somewhat erratic from application to application. Some clip, some compress, some allow up to 109. FCP is normally OK allowing up to 109, but it depends on the exact content of the mov file. Certainly FCP and CS5 handle XDCAM files over 100% differently, FCP is OK, while CS5 appears to compress them down to 104, quicktime player appears to clip.

Re: Gamma curves in F3 flat on top?
 

Thanks Alister, you might be correct, will do test when there's time.

Yes, I experienced even different version of quicktime can interpret different gamma, white clipping, even displayed aspect ratio. ( I been using QT since v2 and now it's v10)