Shooting snow with Arri 16sr and Vision3 250D
Posted 02 January 2010 - 04:06 PM
Posted 02 January 2010 - 05:50 PM
Im shooting a few scenes in lots of snow in upstate New York. The weather reports say it will be overcast with scattered snow showers. The camera i am using is a Arriflex 16sr with Kodak Vision3 250d stock. What would be the best filter combos to deal with the light and not get gray snow. How should I compensate in f/stop with the filter on. I understand my meter might give me a reading for 18% gray when the scene will be leaning more towards white. I'm a novice with this camera and I would really appreciate some help! Thanks!
So you are using a spot meter instead of an incident meter? Are you exposing for people in the scene or only snowy landscapes?
You need ND filters because if the sun comes out, you'll have more light than you can stop down for. The old "Sunny 16" rule tells you that, in direct sunlight on a clear day, the f-stop is f/16 when the shutter speed number under the 1/ equals the ASA -- in other words, if you are shooting at 1/50th at 50 ASA.
Since 1/50th is close to 1/48th (which is the shutter speed when the camera is running at 24 fps with a 180 degree shutter) and 250 ASA is 2 and 1/3 stops faster than 50 ASA, you definitely need some ND filters if the sun comes out.
Besides ND's, Polas may be useful to reduce glare on backlit snow, and ND grads may be useful in locked-off shots where you want to darken part of the frame, though this is less necessary than ND's and Polas.
First of all, I'd start by rating your 250D stock at 200 ASA, just to give the negative a little bit more density / exposure. So you'd need an ND.60 just to get 200 ASA down to 50 ASA. I'd plan on carrying ND.30 (one-stop), ND.60 (two-stops), ND.90 filters (three-stops) at the minimum. You can either put the ND filter on and adjust the ASA rating on the meter to compensate for the filter factor, or you can leave the ASA rating alone and mentally remember to compensate your exposure reading for the filter factor. Just don't forget what filter you have in the camera. Most people put a tag or piece of tape on the side of the mattebox or sunshade telling them what filters are in.
If you are determined to use a spot meter and take reflected readings off of the snow, then it's mainly an issue of deciding how many stops over 18% grey do you want the snow to register as. You can figure that three to five stops over 18% grey is a good starting point, 5-stops over being more or less burnt-out white, 3-stops over being white with texture. If you took a spot meter reading of white snow, it would be exposed as medium grey since the spot meter assumes that everything it reads is 18% grey. So you have to interpret the reading and decide how many stops over and under medium grey your subject is. Or take a grey card out there with you.
An incident meter reads the amount of light falling on the meter dome and doesn't care what the camera is actually pointing at, so if you use and follow the incident meter reading correctly, the values of objects in the scene should fall within normal levels.
Posted 02 January 2010 - 05:52 PM