Paper Negatives at Night
I've been shooting a lot of fiber paper negatives (rather than RC) lately and rate my Arista fiber paper at ISO 20 when shooting in the daytime. However, I wanted to try to take a night time photo just for fun. Was just wondering - does the ISO have to be reduced a stop or two because of the lighting situation at night (different wavelengths than during the day)?
There's the possibility you could start running into reciprocity failure. Never tried this but I thought I'd mention it. I shoot at night a lot using HP5 film, and am not aware of any different "wave lengths." Light seems to be light.
Kent in SD
Well since paper negatives are only sensitive to blue/green light as I understand it, then shooting at night would pose a problem since the light at night is coming mainly from street lights which usually have a very red or orange tint to them. Which is why I thought that I might need to add a couple stops of time to compensate for the effect.
Originally Posted by Two23
I've tried it, and it was an exercise in futility. My homemade camera has an improvised sort of lens in the neighborhood of f/8 (half inch diameter aperture, four inch focal length). Several hours of exposure on a night with a bright full moon yielded nothing. Stopping down to pinhole would complicate things even further.
My paper was Ilford multigrade RC, but I'd be surprised if fiber would give you any better results.
Haha - thanks for the reply. The aperture on the camera I would be using is f/240. If my calculations are right, then at ISO 20 my exposure time would have to be around 10 hours (if the correct exposure time was 30 seconds at f/16 at ISO 100). So lowering the ISO below 20 would make it even more ridiculous. Maybe I'll stick to day time shooting :)
Originally Posted by bvy
who knows, it might work --
i haven't done night paper negatives
but i am sure if you leave the lens open
long enough you will get something ...
try hours instead of minutes ..
have fun !
I recently did a 20 minute timed paper negative exposure with a pinhole camera, deep in a canyon under dim daylight, and found no reciprocity failure; the exposure time used was what I calculated from my meter reading. As long as you're using light that's blue/UV, there should be no problem.
But the real problem in the OP's situation is the wavelength of light at night from artificial light sources doesn't match a daylight spectrum.