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Old July 27th, 2003, 05:05 AM   #1
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Question about the gain

Greetings. I shoot on a Canon XL-1, and would like to know more about the electronic in camera gain feature. I only shoot in manual mode, and try not to let the camera do anything. I run the white balance on locked manual, and take the gain off of auto. Here is my question; the other day, I was shooting outside, and I had forgotten that I had locked the gain at +12 db. When I watched the footage, the colors seemed washed out. The scene wasn’t particularly over exposed, and the colors just did not seem extremely vibrant. Could using the electronic gain be responsible for this sacrifice in color saturation? I have decided to use the gain only for shots in low light conditions, and on a case-by-case basis from now on.

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Old July 28th, 2003, 08:19 AM   #2
 
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sounds like you saturated the CCD. Too much light..too much gain and the camera was unable to compensate.
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Old July 28th, 2003, 01:14 PM   #3
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Avoid using auto DB. This has caused me more headache then anything else. I try to keep the XL1s at zero DB and I make sure that I only use extra DB if absolutly necessary. When you add extra db it can introduce artifacting or a unclean looking image. So best to use external lighting versus using the DB.
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Old July 28th, 2003, 01:41 PM   #4
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-3 is even better.
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Old July 28th, 2003, 08:40 PM   #5
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Runing at +12 dB gain will force you to set the aperture and shutter to provide what is effective low light to the CCD, causing all the kinds of limitations found with low light situations such as increased grain, potentially low saturation in some colors, less effective white balance, poor autofocus response, and perhaps a funny grayscale curve.
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Old July 29th, 2003, 03:14 AM   #6
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Yeah. I have been getting much better results with setting the dB levels on a case by case, and as-needed basis. I never use the automatic setting. Thanks for the replies.
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Old August 1st, 2003, 10:45 AM   #7
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About that grayscale curve...

Don: that's interesting! Why should the grayscale curve differ at +12 Db (if you compensate for exposure in other ways, such as ND filter)? Does the circuitry of the gain settings do anything else but simply amplify the signal? Do you know of any characteristical curves for the XL-1(s) / at various gain settings?

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Old August 4th, 2003, 08:53 PM   #8
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Because when the light reaching the CCD gets very low the output may not be linear.

I've not seen any curves specifically for the XL1.
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Old August 11th, 2003, 07:06 AM   #9
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I'll shoot at -3 or 0 db. If I need more I start looking at other
settings or add light [if possible]. If you start to add gain you'll
notice it very quickly in the resulting image [in my opinion].
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Old August 11th, 2003, 02:04 PM   #10
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In my opinion it all depends.
It's like a grainy b & w photo: it can even add to the atmosphere. Also, if shooting a unique event, in my opinion content goes over form and I'll watch a lower image quality + great content video over a great image quality + poor content video any time. Of course the best is to have both optimal.
I've often cranked up to +12 and have not yet been sorry I did.
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