Is adding gain on camera any different from adding brightness in post? at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Open DV Discussion

Open DV Discussion
For topics which don't fit into any of the other categories.


Reply
 
Thread Tools Search this Thread
Old May 10th, 2009, 03:36 AM   #1
Regular Crew
 
Join Date: Feb 2008
Location: Lancashire
Posts: 40
Is adding gain on camera any different from adding brightness in post?

I'm using a hv30.
If I set a shutter speed or f stop, then go to exposure and make the image brighter (purely gain and not the iris opening i'm guessing), is that any different from just adding brightness or gamma in post?
Gary Douglas is offline   Reply With Quote
Old May 10th, 2009, 05:40 AM   #2
Inner Circle
 
Join Date: Oct 2001
Location: Honolulu, HI
Posts: 2,053
In post you can only extract what's there. If the camera picked up nothing, that's what you'll extract.
__________________
Dean Sensui
Exec Producer, Hawaii Goes Fishing
Dean Sensui is offline   Reply With Quote
Old May 10th, 2009, 07:19 AM   #3
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
Boosting brightness in post is akin to boosting gain on the camera. Boosting brightness in post is amplifying the signal recorded by the camera. Boosting gain in the camera is amplifying the signal from the sensor. A difference though, is that in post, you are boosting a signal recorded at 8 bits (usually), whereas using gain in-camera the DSP is usually working with 10 or more bits.
Robert M Wright is offline   Reply With Quote
Old May 10th, 2009, 08:51 AM   #4
Inner Circle
 
Join Date: Sep 2002
Location: Vancouver, British Columbia (formerly Winnipeg, Manitoba) Canada
Posts: 4,087
Dean is right about "you can only extract what's there". The additional caveat is that once the noise generally associated with "gain up" is added, it is difficult to impossible to remove completely. My PERSONAL position is to use as little gain as possible to get as much exposure as I can in field without adding noticeable noise and then using a 3 way colour corrector (NOT brightness) in post to reset my black, white and gamma (midpoint, sort of...) points.
__________________
Shaun C. Roemich Road Dog Media - Vancouver, BC - Videographer - Webcaster
www.roaddogmedia.ca Blog: http://roaddogmedia.wordpress.com/
Shaun Roemich is offline   Reply With Quote
Old May 10th, 2009, 10:38 AM   #5
Inner Circle
 
Join Date: Jan 2006
Location: Minnesota (USA)
Posts: 2,171
Gain doesn't really add noise. It simply amplifies what noise is already there (along with signal) in the first place, whether it is done in-camera or by doing the equivalent in post.
Robert M Wright is offline   Reply With Quote
Old May 10th, 2009, 10:47 AM   #6
Major Player
 
Join Date: May 2007
Location: San Jose, California
Posts: 858
I might be wrong regarding the new breed of camera sensors, but what I learned in my TV/Film classes was that gain is increased by 'flashing' the sensor with a small amount of light to bring up the minimum sensitivity levels. A sensors 'bucket' won't move a charge unless it detects one...by putting a small amount of light in that 'bucket', it doesn't take as much to have it register and moved along the pipeline. The grain results because these photosites (buckets, as I call them), that normally wouldn't fire, are now firing.

This isn't the same process as adding brightness in post, which accounts for the difference in the resulting image (post brightening tends to wash out an image).
Oren Arieli is offline   Reply With Quote
Old May 10th, 2009, 01:49 PM   #7
Inner Circle
 
Join Date: Sep 2002
Location: Vancouver, British Columbia (formerly Winnipeg, Manitoba) Canada
Posts: 4,087
Quote:
Originally Posted by Robert M Wright View Post
Gain doesn't really add noise. It simply amplifies what noise is already there (along with signal) in the first place, whether it is done in-camera or by doing the equivalent in post.
Actually, gain DOES add noise. Any amplification of an electronic signal past unity gain adds noise.
__________________
Shaun C. Roemich Road Dog Media - Vancouver, BC - Videographer - Webcaster
www.roaddogmedia.ca Blog: http://roaddogmedia.wordpress.com/
Shaun Roemich is offline   Reply With Quote
Old May 10th, 2009, 09:41 PM   #8
Inner Circle
 
Join Date: Oct 2001
Location: Honolulu, HI
Posts: 2,053
I should add a bit to clarify my statement: It's ok to brighten it up a -little- in post. But not a whole lot.

As for during production, shutter speed can be adjusted if you want to keep a particular f-stop. But extending the exposure time also increases the accumulation of noise. As usual, anything extreme can have extreme results.

Best way to find out is to test it and see.
__________________
Dean Sensui
Exec Producer, Hawaii Goes Fishing
Dean Sensui is offline   Reply With Quote
Old May 11th, 2009, 07:29 AM   #9
Regular Crew
 
Join Date: Apr 2009
Location: London. GB
Posts: 29
I would say that its better to adjust the brightens in post, because if your not satisfied whit the results from the gained camera, you can do nothing. But in post, you just have to remake, if you not happy the first time.
John S. Cooper is offline   Reply With Quote
Old May 11th, 2009, 10:25 AM   #10
Major Player
 
Join Date: Dec 2006
Location: Austin, TX
Posts: 773
I'd have to disagree here. I've used HV20s, HG10s and HG20s. I always shoot in cinemode, as that adds the least gain.

I've got to say that adding gain in post is usually less noisy than adding gain in the camera, though I don't know why that is.
__________________
Equip: Panny GH1, Canon HG20, Juicedlink, AT897, Sennh. EW/GW100, Zoom H2, Vegas 8.1
Brian Boyko is offline   Reply With Quote
Old May 11th, 2009, 07:30 PM   #11
Major Player
 
Join Date: Jan 2007
Location: New York City
Posts: 523
Well, ya can't make a silk purse out of a sow's ear (and remember, avoid cliches like the plague).

My theory is to add as little gain as possible in camera--enough to get the image. The nice thing about post is that you can control it better. You are probably rushed and need to concentrate on different things during the shoot but back home, you can take your time and balance noise vs brightness level.
__________________
Andy Tejral
Railroad Videographer
Andy Tejral 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...

Professional Video
(800) 833-4801
Portland, OR

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

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

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 > The Tools of DV and HD Production > Open DV Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 03:45 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network