Orthochromatic Film at night?

[waynecrider]

Has anyone used it for night exposures? I know it's not red sensitive which would allow me to cut it up for 4x5, 2x3 or roll it under a red safelight maybe for pinhole stuff. Does anyone know if or how reciprocity plays a roll in long exposures at night. My Bergger should have a speed of about ISO 12 to 25.

 

[htmlguru4242]

Hmmmm ... that's an interesting quesiton. I ahave neveractually tried this, and I don't know anyone who has, but it may work. There are two problems that i can think of. First is the fact that orthochromatic films tend to be a little slower than Panchromatic films (or, rather, fast ones are not really prevalent), but this shouldn't be a moajor issue. Second, and most importantly, is that most of the light at night is in the orange, red and infrared regions. There is almost no UV, and very little blue and green light. The exposure times would be VERY long, but it can probably be done.

As to pinhole stuff, it'll work great during the day, but a night, I have no idea if you'd even get an image...

Try it though, we'd be nowhere in photography (not no mention in every other field) if people didn't experiment. So play with it and see what you can do.

 

[Donald Qualls]

Most of the natural light available at night is in the blue wavelengths (which is why yellow driving glasses are disrecommended for night driving), so the film should show a speed gain relative to its daylight speed. How much? Sorry, you'll have to test that for yourself. Artificial street lighting, which is almost all sodium vapor with very little mercury vapor or fluorescent and only a smattering of incandescent, will tend the other way; sodium light is almost invisible to ortho film, giving a huge speed loss under yellow street lights. How much? Sorry, you'll have to test for that, too.

For reciprocity, I'd suggest treating it as a "3 for 2" film (same curve as Plus-X and Tri-X -- for every stop change, triple rather than double exposure time) starting at one minute, and test from there -- the stuff doesn't show much if any reciprocity failure when exposed under an enlarger for many seconds, but rather acts a lot like printing paper.

 

[waynecrider]

Artificial street lighting, which is almost all sodium vapor with very little mercury vapor or fluorescent and only a smattering of incandescent, will tend the other way; sodium light is almost invisible to ortho film, giving a huge speed loss under yellow street lights.

I guess this means that there will be very little exposure on the film of light produced by sodium; No light reflection from buildings, tree's etc. If it does register to any extent, then I guess that means the lights won't blow out and the lighting pole itself will show if exposed properly. I look forward to testing this. I guess mercury vapor lights and flourscent in building windows will show.

 

[MikeS]

I've done this (use ortho film for long night exposures). One of my pictures in the gallery "Night Snow" (I think that's what I called it).I used Ilford ortho+ film. It has a daylight speed of around 80, and tungsten speed of about 40. That shot was an hour exposure, and I forget the f-stop at the moment.

-Mike