Is exposing C-log different than usual? at DVinfo.net
DV Info Net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon Cinema EOS Camera Systems

Canon Cinema EOS Camera Systems
For all Canon Cinema EOS models: C700 / C300 Mk. II / C200 / C100 Mk II and EF / PL lenses.

Reply
 
Thread Tools Search this Thread
Old March 14th, 2012, 07:27 PM   #1
Major Player
 
Join Date: Jan 2010
Location: Maassluis, The Netherlands
Posts: 294
Is exposing C-log different than usual?

Since I'll be shooting with a C300 in 2 days from now I wonder whether there are different rules than usual when I use C-log instead of a normal colorprofile.

What is the right way to use (and expose) C-Log?

And is grading different too or not?
(I usually use Colorista and Magic Bullet Looks (not just the presets) to grade my EX1R-footage while using waveforms.)
__________________
Brainstormnavigator searching for the hole in the sky.....
Audiovisual Designer (NL) - http://www.brokxmedia.nl
Walter Brokx is offline   Reply With Quote
Old March 15th, 2012, 11:36 AM   #2
Inner Circle
 
Join Date: Dec 2005
Location: Bracknell, Berkshire, UK
Posts: 4,957
Re: Is exposing C-log different than usual?

Yes. When shooting log you have to consider that in order to record the increases dynamic range, each stop of exposure is allocated a very similar amount of data. But as each extra stop is a doubling of brightness range there is in effect more and more image compression occurring as the image brightness increases. For maximum grade ability, you don't want all your picture information up in the highlights. So generally with a log curve you will underexpose slightly compared to a standard gamma. The norm is to use a mid grey card and expose it so that it is at 38% and reflected white should be somewhere around 70%. Reflected white at 70% then allows headroom for direct light sources like the sky or reflections off shiny surfaces.

That's the theory at least, in practice things will vary from scene to scene, but the primary concern is to not overexpose and to keep highlights well controlled.
__________________
Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com
Alister Chapman is offline   Reply With Quote
Old March 15th, 2012, 12:10 PM   #3
Regular Crew
 
Join Date: Nov 2008
Location: Oakland, CA
Posts: 112
Re: Is exposing C-log different than usual?

I'd also like to hear form others on this. I hear you on the grey/white card method but is there an easier way to get perfect exposure on the fly without a card in the scene? On the EX1, I set zebra 1 to 56 IRE and exposed for zebras on the brightest part of the subject's face (except dark skin people) and the results were always great. But you can't do that with the current C300 firmware. And I also don't like how zebra 1 & 2 look so similar. On the EX1, zebra 2 was much thicker which was fine because that was overexposed anyway.
Graham King is offline   Reply With Quote
Old March 15th, 2012, 12:33 PM   #4
Starway Pictures
 
Join Date: Jul 2005
Location: Studio City
Posts: 581
Re: Is exposing C-log different than usual?

Quote:
Originally Posted by Alister Chapman View Post
Yes. When shooting log you have to consider that in order to record the increases dynamic range, each stop of exposure is allocated a very similar amount of data. But as each extra stop is a doubling of brightness range there is in effect more and more image compression occurring as the image brightness increases. For maximum grade ability, you don't want all your picture information up in the highlights. So generally with a log curve you will underexpose slightly compared to a standard gamma. The norm is to use a mid grey card and expose it so that it is at 38% and reflected white should be somewhere around 70%. Reflected white at 70% then allows headroom for direct light sources like the sky or reflections off shiny surfaces.

That's the theory at least, in practice things will vary from scene to scene, but the primary concern is to not overexpose and to keep highlights well controlled.
That's a great summarization. Cheers, Alister.
Robert Sanders is offline   Reply With Quote
Old March 15th, 2012, 02:14 PM   #5
Inner Circle
 
Join Date: Dec 2005
Location: Bracknell, Berkshire, UK
Posts: 4,957
Re: Is exposing C-log different than usual?

56 IRE for skin tones with standard gamma? That's quite low for a standard gamma, it's more common to use 65 IRE for skin tones. Is that a typo?

With C-log, skin tones I would place bright skin tones around 60IRE.
__________________
Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com
Alister Chapman is offline   Reply With Quote
Old March 15th, 2012, 04:53 PM   #6
Regular Crew
 
Join Date: Nov 2008
Location: Oakland, CA
Posts: 112
Re: Is exposing C-log different than usual?

Nope not a typo. I got that number from an unusual source. It's what Marshall recommends for skin tones when using their false color feature. Looked great to me so I stuck with it.

So 60 in C-Log sounds good to me. Except the C300 only goes down to 70. :-/

Edit: 70 on zebras that is

Last edited by Graham King; March 15th, 2012 at 07:11 PM.
Graham King is offline   Reply With Quote
Old March 15th, 2012, 06:07 PM   #7
Major Player
 
Join Date: Jan 2010
Location: Maassluis, The Netherlands
Posts: 294
Re: Is exposing C-log different than usual?

Thanks for the quick and helpfull replies!

Since I'll be on a very tight schedule, I'm considering using a normal gamma instead of C-log.
(Practising C-log exposure has to wait, I guess ;-) )
__________________
Brainstormnavigator searching for the hole in the sky.....
Audiovisual Designer (NL) - http://www.brokxmedia.nl
Walter Brokx is offline   Reply With Quote
Old March 15th, 2012, 10:15 PM   #8
Regular Crew
 
Join Date: Nov 2005
Location: San Francisco, CA
Posts: 71
Re: Is exposing C-log different than usual?

i really do hope canon updates firmware so we can get zebras below 70
Colin McAuliffe is offline   Reply With Quote
Old March 17th, 2012, 08:39 AM   #9
Regular Crew
 
Join Date: Nov 2010
Location: Toronto
Posts: 70
Re: Is exposing C-log different than usual?

I've emailed pro support up here in Canada about the zebras under 70, and was told it would be forwarded to the correct people. Probably a good idea for everyone to do the same in their region.

Also brought up having selectable display of the SDI. For example only sending TC to the client monitor, instead of everything on the screen.
Nigel Akam is offline   Reply With Quote
Old March 17th, 2012, 05:14 PM   #10
Regular Crew
 
Join Date: Nov 2005
Location: San Francisco, CA
Posts: 71
Re: Is exposing C-log different than usual?

yeah,

i keep calling about once a week asking for a few things...most of them correctable with firmware.

I also really want them to make it so that when you split one source of audio to both channels, you can control the levels of the 2 channels seperately.

as it is now, when you split the one source the two channels are locked at the same volume.
Colin McAuliffe is offline   Reply With Quote
Old March 18th, 2012, 01:10 AM   #11
Regular Crew
 
Join Date: Nov 2008
Location: Oakland, CA
Posts: 112
Re: Is exposing C-log different than usual?

I can't seem to assign two different functions to the wheel on the hand grip and the lower wheel on the body. Has anyone been able to do this? I would request that in a firmware update if it's not currently possible.
Graham King is offline   Reply With Quote
Old March 18th, 2012, 09:26 PM   #12
Regular Crew
 
Join Date: Nov 2005
Location: San Francisco, CA
Posts: 71
Re: Is exposing C-log different than usual?

yes, thaat is my other request. i want to have iris on handle and ISO on the body
Colin McAuliffe is offline   Reply With Quote
Old March 18th, 2012, 09:28 PM   #13
Regular Crew
 
Join Date: Nov 2008
Location: Oakland, CA
Posts: 112
Re: Is exposing C-log different than usual?

That's exactly what I wanted to do!
Graham King is offline   Reply With Quote
Old March 19th, 2012, 08:05 AM   #14
Regular Crew
 
Join Date: Nov 2005
Location: San Francisco, CA
Posts: 71
Re: Is exposing C-log different than usual?

yup....would probably save me an hour over the space of a year...
Colin McAuliffe is offline   Reply With Quote
Old March 19th, 2012, 10:02 AM   #15
Regular Crew
 
Join Date: Nov 2008
Location: Oakland, CA
Posts: 112
Re: Is exposing C-log different than usual?

I assigned ISO to button 1 so I can't say it'd save me an hour per year but it would be nice. Actually, if it could be assigned to color temp I'd probably do that as I do a lot of run & gun.
Graham King is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

B&H Photo Video
(866) 521-7381
New York, NY USA

Scan Computers Int. Ltd.
+44 0871-472-4747
Bolton, Lancashire UK


DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon Cinema EOS Camera Systems

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



All times are GMT -6. The time now is 12:47 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2024 The Digital Video Information Network