View Full Version : ASA rating for Cannon GL2 ???

Daniel Jay
December 15th, 2002, 07:21 PM
Pleae, if anyone knows the ASA rating for Cannon GL2 either drop me an e-mail or post on the reply.

I know little about wave form monitors and can't aford to rent one, also am on a tight time constraint (shooting in two weeks).

Please Help !


P.S. If anyone can lead in a direction of finding an answer that would be awsome as well.

Ken Tanaka
December 15th, 2002, 08:00 PM
This type of question comes up every few months. (I'm still not sure why anyone really finds it relevent.) I don't recall it being discussed re: the GL2 but use the "Search" function on "ISO" to find several threads on the topic. Here's a recent one:

Frank Granovski
December 15th, 2002, 08:39 PM
You might want to read this, and the links I have posted there:

Don Palomaki
December 16th, 2002, 03:31 AM
The DVINFO.NET XL1 section has an extensive discussionof ISO ratings. Bottom line is that the rating has little meaning for video because video is different than film. You can come up with an exposure index for your applications that suits your way of shooting.

Pick a typical scene, and in manual mode, adjust the aperture, shutter and gain to produce an image you like, then meter the scene with a good light meter. Adjust the meter ISO to produce the same aperture and shutter. That is the nominal exposure index (aka: ISO rating) for the selected gain setting. and scene.

Using zebra is a good way of judging exposure of highlights. You may find the ISO is in the range or 320, give or take a stop or two.

Note that the gain setting is a bit like push processing with film.

Daniel Jay
December 17th, 2002, 11:11 PM
Thanks for the relpy's, haven't had time yet to sufficently investigate your relpy's (super busy latley) but I appreciate the help.

I still think that shootnig for one constant ASA reading would product the best results. This will be my first Mini DV shoot in a narrative form with specific focus on lighting, but I can't ssem to understand why one would not need to know such a vaulable thing as chips sensitivity to light.

I'll holler back when I get a hot minute to sit and think about things.


Don Palomaki
December 18th, 2002, 04:32 AM
ASA/ISO is for film because film has to be processed to evaluate the exposure - there is no immediate feedback. Film speed and a light meter are used to estimate the proper exposure. Most pros will bracket the exposure to be sure - if they can.

Conside that the camcorder is the worlds most detailed exposure meter. Video goves immediate feedback to a monitor or the EVF. Thus you can judge the esposure of the details in the scene that are important to you and adjust exposure accordingly. A light meter is of help when lighting a scene without a camera present. But best to trust the camera image rather than a light meter for the final exposure.

Note also that film light meters/metering is traditionally based on a 18% reflectance gray card. That works for average scenes and film. Because video has a different response curve (not as wide latitude as film) you may need a different setting for good results. And any 'average' setting may blow out important highlights or lose vital detail in shadows.

Jeff Donald
December 18th, 2002, 06:20 PM
If you were shooting film, and before you pressed the button and exposed the film, you could see exactly what your print was going to look like, would you need a light meter? No, because you could adjust your shutter speed and lens opening (aperture) to get exactly the image you wanted.

Well, you've got that with video. Hook the output of the camera into a small monitor and you'll see exactly what your video looks like. The shadows, the highlights, everything is there for you to see.

Instead of buying a lightmeter, put the money towards a small monitor.


Ken Tanaka
December 18th, 2002, 07:26 PM
Don and Jeff hit the nail on the head. ISO ratings and light meters are predictive performance tools which exist to augment the fact that when shooting film you cannot see the end product until it comes back from the lab. As Don said, a video camera is "...the worlds most detailed exposure meter". What you see in a (properly calibrated) viewfinder is what you'll get on the tape, especially in the case of digital video.

There are circumstances where you may find a light meter handy on a digital video shoot. But "normalizing" your shooting against readings and ratings designed for a completely different medium doesn't make any sense to me. The best action you can take is to learn everything there is to know about your particular video camera; how it responds to situations and settings, how each control is best applied, etc.

Don Palomaki
December 19th, 2002, 04:41 AM
On latitude. Divital video is 8 bit. Isn't
negaive film is on the order of 12-14 bits.

Jeff Donald
December 19th, 2002, 06:07 AM
The digital files from film are 10 bit log and have 1024 discreet levels from black to white. DV is 8 bit and only 256 discreet levels from black to white. The real trick is matching the density of film (D-Min, D-Max). Incorrect (compressed) density conversion shows up typically as banding. The 8 bit files from DV and their 256 levels are not enough data to prevent banding.