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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old January 20th, 2007, 01:23 AM   #1
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Gain switch settings?

Just curious what people are setting for their 3 gain switch settings. Is it different for indoors/outdoors, good lighting vs low lighting? Are people getting away with using 12db in low light without horrible grain, or is 6db the highest safe value?

I find myself wishing there were a gain wheel instead of a 3-position switch, because I wish I could have access to -3, 0, 3, and 6. Changing the switch settings in the menu doesn't take long, but there's something about pushing a few buttons instead of one :P
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Old January 20th, 2007, 03:11 AM   #2
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I've just been on an IOV wedding video course and they advised me I really should be using 0, 3 and 6db as the settings. I have them set at that but I haven't experimented yet.

Has anyone used the gradual change between the gain settings customisable option? Is it effective or is it better to get an instant fix?
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Old January 20th, 2007, 03:21 AM   #3
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Personally I have mine set to -3db, 3db, 6db. I'd never go higher than six... but that's because the type of work I do is mostly pretty controlled.
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Old January 20th, 2007, 03:22 AM   #4
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Quote:
Originally Posted by Mark G. Roberts
Has anyone used the gradual change between the gain settings customisable option? Is it effective or is it better to get an instant fix?
The gradual change is a smooth ramp (perhaps takes a second). It's much prettier, but doesn't work between -3db and anything.
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Old January 20th, 2007, 07:08 PM   #5
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I set mine to -3dB, 0dB and 6dB. The A1 is a bit noisy at anything above -3dB so if there is a need to use more than 0dB I would also want to change the noise reduction and coring settings. I'm still working on matching some custom presets to different gain settings for convenience but in the meantime I just use a "scratch" preset for ad hoc adjustments.

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Old January 21st, 2007, 12:01 AM   #6
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Why would they tell you not to use -3db. I use -3db on everything other than lowlight.
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Old January 21st, 2007, 04:08 AM   #7
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Quote:
Originally Posted by Richard Hunter
I would also want to change the noise reduction and coring settings.
Richard
Where can I find those?
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Old January 21st, 2007, 04:39 AM   #8
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It's in the Menu, under Customize/Custom Preset. Of course, the sheer amount of things you can adjust will give you a headache, but you can also look for other threads about custom presets in this forum to get help.

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Old January 21st, 2007, 09:53 AM   #9
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I shoot normally at a -3db, and the other positions are zero and +3.
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Old January 22nd, 2007, 09:23 AM   #10
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So what does -3 db mean?

How can you take away what isn't there if gain is 0?

Is -3 db gain another form of noise reduction?

I feel a Nigel Tufnell moment coming up
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Old January 22nd, 2007, 06:43 PM   #11
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Hi Mark. The output from the sensor (CCD) is an analogue voltage that has to be converted to digital in the camera, before processing, compression and recording to tape. The gain switch is used to boost or cut the analogue voltage before the conversion to digital data. Positive values represent boost, negative values mean attenuation.

Why would you want to attenuate the voltage? Yes, noise reduction is one factor. If there is a lot of available light then the CCD output voltage is nice and high. Attenuating this voltage also attenuates any noise so the blacks should look cleaner. Another reason to attenuate the voltage is to reduce the effective exposure which allows you to open up the iris a bit more and get a slightly shallower depth of field.

By the way, -3dB just means that the CCD signal voltage is attenuated by around 30%. +3dB means a boost of around 40%, and 0dB means no boost or attenuation.

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Old January 23rd, 2007, 07:33 AM   #12
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Many thanks Richard. The mists have cleared.

I'll give it a try
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