Auto vs. Manual Exposure at DVinfo.net

Leigh Hanlon · March 21st, 2005, 04:27 PM

What's the range in gain that the GL2 employs when the camera is in Auto mode? I ask because I've noticed that when I switch the GL2 from Auto to Manual, I frequently have to open the lens all the way, set shutter to 1/60 and increase the gain to duplicate the exposure level I'm getting in Auto. Often, the result is too noisy/grainy.

Does Auto actually set a fractional gain level that we can't set using Manual?

Graham Bernard · March 21st, 2005, 05:24 PM

At last! Somebody else is seeing this . . thank you! - Grazie

Chris Hurd · March 21st, 2005, 05:36 PM

I think when it's in Auto, it's accessing the slower shutter speeds so what you might be seeing is 1/30th sec. shutter as well as some gain. Just a guess though.

Leigh Hanlon · March 21st, 2005, 05:57 PM

Chris,

I thought it might be dropping to 1/30, as well, but I haven't noticed any motion-related artifacts when the camera is in Auto mode. Maybe it's able to determine the maximum fractional increase in gain to avoid any overt noisiness?

In other words, maybe the highest gain the GL2 sets at Auto is still well below the lowest you can set it to on Manual?

Leigh

Pietro Jona · March 22nd, 2005, 02:53 AM

To know what the camera is doing in auto mode I do like this, I'm not sure it is correct but i guess it is: camera in auto mode, push the exposure lock button. Turn to manual, you have the aperture, the shutter speed and the gain set for what the camera thinks it is a correct exposure. Every time you switch from auto to manual after locking the exposure you'll see the exposure meter in the middle of the range, saying you are exposing correctly, this is why i think it is the correct way to see what the auto mode decided. If you switch from auto to manual without locking the exposure the settings will be the ones you used the last time you shot i manual.
When the light is strong, I think I noticed that the camera tends to adjust exposure by changing (closing) the aperture first, then asking you to use the ND filter and then using faster shutter speeds. When it is dark, the camera asks you not to use the ND filter, opens the iris and then starts pushing with gain. I never noticed the camera using a slower shutter speed than 1/50 (XM2).

March 21st, 2005, 04:27 PM	#1
Leigh Hanlon Regular Crew Join Date: Jan 2005 Location: Chicago, USA Posts: 64	Auto vs. Manual Exposure What's the range in gain that the GL2 employs when the camera is in Auto mode? I ask because I've noticed that when I switch the GL2 from Auto to Manual, I frequently have to open the lens all the way, set shutter to 1/60 and increase the gain to duplicate the exposure level I'm getting in Auto. Often, the result is too noisy/grainy. Does Auto actually set a fractional gain level that we can't set using Manual? __________________ Leigh Hanlon \| Chicago, USA GL2 - Final Cut Studio

March 21st, 2005, 05:36 PM	#3
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	I think when it's in Auto, it's accessing the slower shutter speeds so what you might be seeing is 1/30th sec. shutter as well as some gain. Just a guess though. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

March 21st, 2005, 05:57 PM	#4
Leigh Hanlon Regular Crew Join Date: Jan 2005 Location: Chicago, USA Posts: 64	Chris, I thought it might be dropping to 1/30, as well, but I haven't noticed any motion-related artifacts when the camera is in Auto mode. Maybe it's able to determine the maximum fractional increase in gain to avoid any overt noisiness? In other words, maybe the highest gain the GL2 sets at Auto is still well below the lowest you can set it to on Manual? Leigh __________________ Leigh Hanlon \| Chicago, USA GL2 - Final Cut Studio

March 21st, 2005, 05:24 PM	#2
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	At last! Somebody else is seeing this . . thank you! - Grazie

March 22nd, 2005, 02:53 AM	#5
Pietro Jona Regular Crew Join Date: Jul 2003 Location: italy Posts: 172	To know what the camera is doing in auto mode I do like this, I'm not sure it is correct but i guess it is: camera in auto mode, push the exposure lock button. Turn to manual, you have the aperture, the shutter speed and the gain set for what the camera thinks it is a correct exposure. Every time you switch from auto to manual after locking the exposure you'll see the exposure meter in the middle of the range, saying you are exposing correctly, this is why i think it is the correct way to see what the auto mode decided. If you switch from auto to manual without locking the exposure the settings will be the ones you used the last time you shot i manual. When the light is strong, I think I noticed that the camera tends to adjust exposure by changing (closing) the aperture first, then asking you to use the ND filter and then using faster shutter speeds. When it is dark, the camera asks you not to use the ND filter, opens the iris and then starts pushing with gain. I never noticed the camera using a slower shutter speed than 1/50 (XM2).