Light Meters and GL2 ISO value... at DVinfo.net

Tyler Panah · December 24th, 2005, 02:18 AM

Hey guys, I have a question. I bought a Minolta Ivf light meter, hopefully it has utility with video and not just still cameras. There are certain setttings u have to type in to get the proper f-stop readings. U have to know the ISO value of the film, but I think there's an ISO value for video cams that can be typed in. Does anyone know the ISO value for the GL2? Also, there is a "time setting" on the light meter, and when I adjust the time, the f-stop reading changes, so I must know what the proper time setting is too. Can anyone help, is this meter not for video?

Tyler Panah · December 25th, 2005, 11:20 PM

The ISO stands for International Standards Organization, and I believe it's synonimous with ASA (American Standards Association) and the EI (Exposure Index). Does anyone use light meters? Again, does anyone know the ISO, ASA, or EI for the Canon GL2?

Dale Guthormsen · December 25th, 2005, 11:48 PM

Tyler,

I come from a long history of photography. Asa of film dictates the speed of the film, historically the faster the asa the more grain you would get in your enlargements, but let you shoot in less light with out extra light, that improved much over the years, but still holds true. An easy example would be that if you used asa 125 then on a sunny day you could shoot 125 speed with an aperature of f 16 and get a reasonable exposure. If you wanted to make 16 x 20 enlargements it was always better to use a slower ASA to reduce grain. Of course larger negatives helped too. the entire relationship of aperature and shutter speed have major effect on the outcome of your pictures.

In video you are not working with film so the idea of asa doesn't really make a lot of sense. with video you can adjust exposures a few different ways, none of which a light meter is essential. I personally like to use the tv mode in my gl2. For greater depth of field I shoot slower (reduces the aperature giving more depth of field) , for less depth of field you just go the other direction.
I shoot wildlife and do not have alot of time to mess about, if you have lots of time straight manual control is best.
do you need a light meter, not really. I have one and never use it except for film.

Perhaps one of our more professional videographers can expand on this idea.

I do not know if I helped you here.

gus

Tyler Panah · December 26th, 2005, 01:25 PM

Yes, it helped Gus thanks.

I still know there's a proper ISO to punch into the light meter, even for Video cameras. I think there's a way to figure it out if you know the other parts of the equation using algebra, and "solving for X." I was just hoping someone has already done that...I want to be able to get proper readings in order to have the contrast ratios I want on a subject's face. So i need the ISO of the GL2, and I need to understand the "time" setting on this meter, can anyone at least point me in the right direction?

David Langley · December 26th, 2005, 07:29 PM

You can get some information and procedures here http://www.cybercollege.com/asavideo.htm

Tyler Panah · December 26th, 2005, 11:01 PM

Thanks David, nice instructions on that page, that answers some of my questions.

Don Palomaki · December 28th, 2005, 04:55 PM

The reason for ISO/ASA ratings for film and the use of light meters is because you have to wait for the film to be processed to see if the exposure was correct. The light meter helps the photographer select the exposure.

Video camera, via a monitor, gives instant feedback (no wait to see the exposure) and as a bonus you can see whether or not the highlights or shadows in which you are you are especially interested are properly exposed - it is in effect a light meter. (And then some viewer can use his TV image controls to mess-up the image.)

However, a light meter can be of help when lighting a set before the video camer arrives, and for showmanship.

Gain is like push processing: 6 dB is effctively one stop.

The response of video to light is different than film, so the meaining of an ISO rating would be different, and depend on how you set it. The method provided in the above referenced web site is a reasonable method. The key to using a light meter and ISO ratings is to understand how the results ultimately turn out in the video.

Tyler Panah · December 31st, 2005, 08:36 AM

Thanks Don!

December 24th, 2005, 02:18 AM	#1
Tyler Panah New Boot Join Date: Jul 2005 Posts: 20	Light Meters and GL2 ISO value... Hey guys, I have a question. I bought a Minolta Ivf light meter, hopefully it has utility with video and not just still cameras. There are certain setttings u have to type in to get the proper f-stop readings. U have to know the ISO value of the film, but I think there's an ISO value for video cams that can be typed in. Does anyone know the ISO value for the GL2? Also, there is a "time setting" on the light meter, and when I adjust the time, the f-stop reading changes, so I must know what the proper time setting is too. Can anyone help, is this meter not for video?

December 25th, 2005, 11:48 PM	#3
Dale Guthormsen Inner Circle Join Date: Jun 2005 Location: Saskatchewan Posts: 3,048	light meters Tyler, I come from a long history of photography. Asa of film dictates the speed of the film, historically the faster the asa the more grain you would get in your enlargements, but let you shoot in less light with out extra light, that improved much over the years, but still holds true. An easy example would be that if you used asa 125 then on a sunny day you could shoot 125 speed with an aperature of f 16 and get a reasonable exposure. If you wanted to make 16 x 20 enlargements it was always better to use a slower ASA to reduce grain. Of course larger negatives helped too. the entire relationship of aperature and shutter speed have major effect on the outcome of your pictures. In video you are not working with film so the idea of asa doesn't really make a lot of sense. with video you can adjust exposures a few different ways, none of which a light meter is essential. I personally like to use the tv mode in my gl2. For greater depth of field I shoot slower (reduces the aperature giving more depth of field) , for less depth of field you just go the other direction. I shoot wildlife and do not have alot of time to mess about, if you have lots of time straight manual control is best. do you need a light meter, not really. I have one and never use it except for film. Perhaps one of our more professional videographers can expand on this idea. I do not know if I helped you here. gus

December 28th, 2005, 04:55 PM	#7
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	The reason for ISO/ASA ratings for film and the use of light meters is because you have to wait for the film to be processed to see if the exposure was correct. The light meter helps the photographer select the exposure. Video camera, via a monitor, gives instant feedback (no wait to see the exposure) and as a bonus you can see whether or not the highlights or shadows in which you are you are especially interested are properly exposed - it is in effect a light meter. (And then some viewer can use his TV image controls to mess-up the image.) However, a light meter can be of help when lighting a set before the video camer arrives, and for showmanship. Gain is like push processing: 6 dB is effctively one stop. The response of video to light is different than film, so the meaining of an ISO rating would be different, and depend on how you set it. The method provided in the above referenced web site is a reasonable method. The key to using a light meter and ISO ratings is to understand how the results ultimately turn out in the video. __________________ dpalomaki@dspalomaki.com

December 25th, 2005, 11:20 PM	#2
Tyler Panah New Boot Join Date: Jul 2005 Posts: 20	The ISO stands for International Standards Organization, and I believe it's synonimous with ASA (American Standards Association) and the EI (Exposure Index). Does anyone use light meters? Again, does anyone know the ISO, ASA, or EI for the Canon GL2?

December 26th, 2005, 01:25 PM	#4
Tyler Panah New Boot Join Date: Jul 2005 Posts: 20	Yes, it helped Gus thanks. I still know there's a proper ISO to punch into the light meter, even for Video cameras. I think there's a way to figure it out if you know the other parts of the equation using algebra, and "solving for X." I was just hoping someone has already done that...I want to be able to get proper readings in order to have the contrast ratios I want on a subject's face. So i need the ISO of the GL2, and I need to understand the "time" setting on this meter, can anyone at least point me in the right direction?

December 26th, 2005, 07:29 PM	#5
David Langley Tourist Join Date: Apr 2005 Posts: 1	You can get some information and procedures here http://www.cybercollege.com/asavideo.htm

December 26th, 2005, 11:01 PM	#6
Tyler Panah New Boot Join Date: Jul 2005 Posts: 20	Thanks David, nice instructions on that page, that answers some of my questions.

December 31st, 2005, 08:36 AM	#8
Tyler Panah New Boot Join Date: Jul 2005 Posts: 20	Thanks Don!