infrared film

[jordi]

Can you help me about the ASA for the Kodak HIE? I don't know what is better sensibility to use this fim.

Thanks.

[oftheherd]

If it is like it used to be, Kodak advised equivalent of ASA 25 with the red filter. I seem to remember it dropped a little bit if you used an opaque IR filter.

No matter, you will have to experiment with your camera and light meter.

[jordi]

Yes, I've read that in the case of the film, but, I've read what people have used 200 ASA.

[FrankS]

When using this film, I set the light meter to ASA 400. If I use a filter I compensate depending on the filter used. This works for me when the day is bright and sunny.

[Mike Richards]

Meters and ISO settings provide at best a starting point, since meters vary on their sensitivity to infrared. Exposure on a sunny day with a red filter in place should come out about 1/125 at f11, which is about 50 ISO; about 1-2 stops more for an opaque filter (25-12 ISO). This is for an external meter. If you have a through the lens meter in your camera, I recommend you put the filter in place and meter a sunny day scene. Then adjust the ISO until you get 1/125 at f11. That should give you a good starting point. This is probably what jordi is referring to with ISO 200. I've found on my M6TTL that 400 is about right with a B+W 093 (opaque) filter in place, for example. It all depends on how sensitive the in camera meter is to infrared. Whatever way you meter, you need to bracket and experiment a bit. With HIE, you will get the best effects in good sunlight. Clouds seem to reduce infrared more than they do visible light, so in cloudy conditions, you will need to open up a bit more, and the infrared effect will be less. So to get the most infrared impact from your images, you will want to be shooting in bright sunlight, anyway. There's a lot of good info at:
http://www.a1.nl/phomepag/markerink/mainpage.htm
You can also sign up there for the infrared digest. Good shooting and good luck.

[Brian Sweeney]

Most modern light meters are not going to be sensitive to infrared. "Blue" SPD's have a filter over them to cutoff the IR. Unfiltered Silicon Cells are sensitive to IR out to 1,100 angstroms. One of my "rainy day" projects is to take an old selenium meter and substitute a Silicon cell (Radio Shack) into it. Use it with a Hot Mirror filter for Visible, use it with a red filter or Wratten (88? 89? I forget, but I have one) filter for IR.

Photo.net article on CDS and Selenium Sensitivity for Infrared.

Film, Filters, and ISO Speed: Another Page of the Photo.net article on Infrared