2 black stretch or not 2 black stretch? at DVinfo.net

John Vincent · February 6th, 2006, 03:45 AM

When you are setting the pedistal and black stretch levels, I believe that it effects the amount/denisty of blacks and shadows.

I'm am confussed as to what the exact effect of black is. Shouls one use it if they hope to go to a films out? I've read some conflicting things on this point. Also, one poster (I can't remember which thread now) claimed that the film-out option on the JVC actually does the opposite of what you'd want it to.

Any advice on the pedistal level/black stretch settings? Thanks,

John

Greg Corke · February 6th, 2006, 02:12 PM

I can only speak from my own tests and would say that if its a film look your after I've found that master black somewhere between Normal and -4 and black compress 0 to -1 in cinemode of course. Give it a go tell me what you think. Others may disagree but I find this gives a real nice rich contrast although maybe the colour is a lttle muted for some I, however, personally feel this is more filmic (but hey what do I know).

Regards Greg C

John Vincent · February 7th, 2006, 01:43 AM

Thanks Greg - I'll try it tomorrow + let you know...

john

Tim Dashwood · February 7th, 2006, 03:48 AM

John,

If you want to extend the dynamic range of the camera, then black stretch will increase sensitivity in the shadow areas. It is not like turning the brightness up on your monitor. Your blacks will not go milky.
I set my master pedestal to -1 or -2 (which still delivers rich blacks) but generally use a black stretch of 3 and a knee of 80%. This allows for the widest possible dynamic range. You can always bring your shadows down in post if needed, but the opposite is not true if you crush them too much (using black compress) when you shoot.

If you want to see the effects of the different parameters on the gamma response curves have a look at my tests here:
http://homepage.mac.com/timdashwood/...X-Sorenson.mov

There is also more info here:
http://www.dvinfo.net/conf/showthread.php?t=52256

John Vincent · February 7th, 2006, 03:55 AM

Thanks Tim - I'll try the settings. Does the various black stretches add any grain/noise? If not, there would seem to be no reason not to use the stretch...

John

Greg Corke · February 7th, 2006, 04:34 AM

got my stretch and compress mixed up, sorry. I still haven't mastered thinking one thing and writing another.
Greg C

February 6th, 2006, 03:45 AM	#1
John Vincent Trustee Join Date: Sep 2005 Posts: 1,065	2 black stretch or not 2 black stretch? When you are setting the pedistal and black stretch levels, I believe that it effects the amount/denisty of blacks and shadows. I'm am confussed as to what the exact effect of black is. Shouls one use it if they hope to go to a films out? I've read some conflicting things on this point. Also, one poster (I can't remember which thread now) claimed that the film-out option on the JVC actually does the opposite of what you'd want it to. Any advice on the pedistal level/black stretch settings? Thanks, John

February 6th, 2006, 02:12 PM	#2
Greg Corke Major Player Join Date: Jul 2005 Location: London, UK Posts: 245	Hi John I can only speak from my own tests and would say that if its a film look your after I've found that master black somewhere between Normal and -4 and black compress 0 to -1 in cinemode of course. Give it a go tell me what you think. Others may disagree but I find this gives a real nice rich contrast although maybe the colour is a lttle muted for some I, however, personally feel this is more filmic (but hey what do I know). Regards Greg C

February 7th, 2006, 03:48 AM	#4
Tim Dashwood Wrangler Join Date: Aug 2005 Location: Toronto, ON, Canada Posts: 3,637	John, If you want to extend the dynamic range of the camera, then black stretch will increase sensitivity in the shadow areas. It is not like turning the brightness up on your monitor. Your blacks will not go milky. I set my master pedestal to -1 or -2 (which still delivers rich blacks) but generally use a black stretch of 3 and a knee of 80%. This allows for the widest possible dynamic range. You can always bring your shadows down in post if needed, but the opposite is not true if you crush them too much (using black compress) when you shoot. If you want to see the effects of the different parameters on the gamma response curves have a look at my tests here: http://homepage.mac.com/timdashwood/...X-Sorenson.mov There is also more info here: http://www.dvinfo.net/conf/showthread.php?t=52256 __________________ Tim Dashwood

February 7th, 2006, 04:34 AM	#6
Greg Corke Major Player Join Date: Jul 2005 Location: London, UK Posts: 245	oops got my stretch and compress mixed up, sorry. I still haven't mastered thinking one thing and writing another. Greg C

February 7th, 2006, 01:43 AM	#3
John Vincent Trustee Join Date: Sep 2005 Posts: 1,065	Thanks Greg - I'll try it tomorrow + let you know... john

February 7th, 2006, 03:55 AM	#5
John Vincent Trustee Join Date: Sep 2005 Posts: 1,065	Thanks Tim - I'll try the settings. Does the various black stretches add any grain/noise? If not, there would seem to be no reason not to use the stretch... John