Question about Lux Ratings

eejackson wrote on 1/24/2004, 2:26 PM

Hi All:
Ok, I've been contemplating all day as to wheter or not I should post this question, so please bear with me and don't laugh too hard....

I am outsourcing a cameraman to shoot a couple of weddings for my teeny ,tiny ,little video editing studio and I need to ask him a question in regard to the LUX rating of his camera. The problem is, I myself , don't fully understand the question. I was told that I should ask him what the lux rating of his camera is. Once he answeres, I should then ask him if the rating is the same at zero gain. I know that lux rating is in regard to how the camera will overcome low-light situations, I just don't understand what zero gain is.....

Oh God, I feel the bananas being thrown at me already.

Comments

farss wrote on 1/24/2004, 2:34 PM

I think it's only relative within a given camera. I know on some cameras you can select Low, Medium and High gain and in the setup define what you want those set at.

I think the camera should spec 0 gain gives a certain S/N ratio.
As to the lux rating they now seem to spec aperture at lux e.g. 2 lux for F4. It's all a bit meaningless unless you know the S/N.

I'd ignore it and just ask what camera he has.

johnmeyer wrote on 1/24/2004, 6:48 PM

If getting quaity video in low light is the objective, then the Sony VX-2000 or VX-2100 are among the best "prosumer" camcorders in this respect.

ArmyVideo wrote on 1/24/2004, 7:28 PM

No banannas from me... I think we all ask questions (or want to) that we fear other folks will think us foolish for.

You're right about the lux rating- it defines how a camera will handle low light. My understanding is the lower the lux rating, the less light a camera needs to capture an image. I.e., a camera shooting with IR would have a lux rating of 0, as it is capturing an image using no visable light. The problem is that capturing an image, and capturing a useable image are often two different animals. Some cameras claim to have a low lux rating, but to achve that, you have to shoot at a slower frame-rate with the gain bumped all the way up, which results in a jerky, grainy image that may or may not be worth using.
To answer your question about gain though, it's an electronic system used to boost the light within an image. Most prosumer cameras (and all commercial rigs) have a gain setting. 0 gain is no enhancement at all. Anything above zero is a relative degree of enhancement. You can think of it the same as adding a +dB boost in the audio stream. Add a little (+3) and you're enhancing the level a bit. Add a lot (+10) and chances are you're overmodulating and the audio is useless. For instance, we shoot with Sony DVW709's at work- they have a "turbo gain" button. These boost incoming light +48dB (nearly 7 f-stops). That's great for checking focus or setting up shots in low light, but leave it on too long and the TD starts sweatin'.

Basicly the reason to ask is to find out what kind of image their camera will capture in a low light siuation (such as the dance floor at the reception).

Hope this helps -
Brian

eejackson wrote on 1/24/2004, 7:38 PM

Thanks everbody, I now have a much better understanding. I really appreciate all of your input.
Lori J.