Gain switch settings? at DVinfo.net

James Duffy · January 20th, 2007, 01:23 AM

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

Mark G. Roberts · January 20th, 2007, 03:11 AM

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?

Alex Leith · January 20th, 2007, 03:21 AM

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.

Alex Leith · January 20th, 2007, 03:22 AM

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.

Richard Hunter · January 20th, 2007, 07:08 PM

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.

Richard

Andrew Ott · January 21st, 2007, 12:01 AM

Why would they tell you not to use -3db. I use -3db on everything other than lowlight.

Rik van der Kroon · January 21st, 2007, 04:08 AM

Quote:

Originally Posted by Richard Hunter

I would also want to change the noise reduction and coring settings.
Richard

Where can I find those?

Richard Hunter · January 21st, 2007, 04:39 AM

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.

Richard

Bill Pryor · January 21st, 2007, 09:53 AM

I shoot normally at a -3db, and the other positions are zero and +3.

Mark G. Roberts · January 22nd, 2007, 09:23 AM

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

Richard Hunter · January 22nd, 2007, 06:43 PM

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.

Richard

Mark G. Roberts · January 23rd, 2007, 07:33 AM

Many thanks Richard. The mists have cleared.

I'll give it a try

January 20th, 2007, 01:23 AM	#1
James Duffy Regular Crew Join Date: Dec 2003 Location: DC, USA Posts: 97	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 __________________ http://duffx.com

January 20th, 2007, 03:21 AM	#3
Alex Leith Major Player Join Date: Mar 2005 Location: Northampton, England Posts: 500	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. __________________ Alex

January 20th, 2007, 03:11 AM	#2
Mark G. Roberts Regular Crew Join Date: Jan 2007 Location: Reading, United Kingdom Posts: 29	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?

January 20th, 2007, 07:08 PM	#5
Richard Hunter Trustee Join Date: Dec 2004 Location: Lipa City Batangas, Philippines Posts: 1,110	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. Richard

January 21st, 2007, 12:01 AM	#6
Andrew Ott Regular Crew Join Date: Oct 2006 Location: Austin, Texas Posts: 62	Why would they tell you not to use -3db. I use -3db on everything other than lowlight.

January 21st, 2007, 04:39 AM	#8
Richard Hunter Trustee Join Date: Dec 2004 Location: Lipa City Batangas, Philippines Posts: 1,110	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. Richard

January 21st, 2007, 09:53 AM	#9
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	I shoot normally at a -3db, and the other positions are zero and +3.

January 22nd, 2007, 09:23 AM	#10
Mark G. Roberts Regular Crew Join Date: Jan 2007 Location: Reading, United Kingdom Posts: 29	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

January 22nd, 2007, 06:43 PM	#11
Richard Hunter Trustee Join Date: Dec 2004 Location: Lipa City Batangas, Philippines Posts: 1,110	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. Richard

January 23rd, 2007, 07:33 AM	#12
Mark G. Roberts Regular Crew Join Date: Jan 2007 Location: Reading, United Kingdom Posts: 29	Many thanks Richard. The mists have cleared. I'll give it a try