IR filtration questions

[Christopher Walrath]

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Hi, all. I'm going to do some IR for the first time. Eveyone suggests an R72 filter. What is the filter factor for an R72?

[Christopher Walrath]

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Bump.

[MattKing]

Chris:

Your question about an appropriate filter factor for an R72 filter isn't as simple as it may seem.

The problem with filter factors, is that they are dependant on the film involved, and the spectrum of the light available.

I refer to two photos in my APUG gallery. Both were shot on the same roll of Rollie 400 on the same day using the same camera, lens and shutter. I used the same meter and metering technique. Naturally, they received the same development.

For the first, I adjusted the exposure by giving it an additional 7 stops:

http://www.apug.org/gallery/showphot...80&ppuser=6479

For the second, I adjusted the exposure by giving it an additional 5 stops:

http://www.apug.org/galleryshowphoto.php?photo=35625&ppuser=6479

If you use a different film in the same light, you might need a different adjustment. If you use the same film under different light you again may need another adjustment.

I find bracketing to be critical.

Hope this helps.

Matt

[Christopher Walrath]

So, basically, get some film, shoot it through my red filter, bracketing, and see what turns up. As I was actually planning.

Thanks for the confirmation. I guess I was naively hoping the IR fairy would come doink me on the head and say, 'HERE'S WHATCHA DO!'

Yeah, I knew better.

[Travis Nunn]

If you're trying IR for the first time you should bracket like crazy to find what works best for you. IR is not an exact science.

[Christopher Walrath]

Kinda what I figured. Another question. Would a stronger filter than a Red with a FF of 4 produce more dramatic results? Not like I have one to try it on but I was just wondering as to general results from others who have used. (You know, in another context that might not sound so good.)

[GJA]

Best would be a 89 filter. They are completely black; thus there is no filter as both bright light and dim light would read on on your meter as no light at all.

Ive heard that it should be shot through such a filter at around ISO 3. But with some experimentation im sure you will create your own system/methodology.

Dont forget to keep a detailed log!

[Toffle]

Depending on the film I am using, I meter for ISO 1.5-6 for filtrating with an R72 filter... 1.5 to really bring out the IR effects for Maco/Efke films, and 6 for Ilford SFX. These settings give me negatives that I can work with in the darkroom without too much fiddling around. As the anticipated effect is not to achieve "natural" tones, I tend not to do very much dodging or burning of my IR images.

Cheers,

[Christopher Walrath]

Yeah. I think a roll of bracketing, maybe two, of different lighting situations and varying subjects is of the order.

[keithwms]

http://www.apug.org/forums/forum48/6...omparison.html