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I recently bought both the SFX200 infrared film as well as the Hoya R72 IR filter.

I searched online and I'm a bit confused about exposure compensation.

With the combination above, how many stops of light are cut (approximately)?

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SFX200 is sensitive to light up to 740nm.

The Hoya R72 blocks all wavelengths up to 720nm.

So, first and foremost, you need to be aware that you are photographing a range that you can't see and your camera can't meter - and it's a very slim range at that.

Ilford's Tech Info recommends increasing the exposure by 4 stops over what your meter would say when the filter is off.

But, that's not quite the whole story. If your shutter speeds are starting to get long, you may have to also account for reciprocity failure. Ilford lists a correctional factor of exposure^1.43.

But, also consider that IR light is both absorbed and reflected differently than visible light. For example, it gets absorbed by water and scattered and reflected by foliage. You'll have to keep this in mind, especially when it comes to shadow detail.

So, the reality is: taking a meter reading and then adjusting by 4 stops will be your baseline. You'd be wise to bracket your shots.


Sidenote: Also be aware that IR focuses differently as well. Lenses typically have an IR adjustment line/lines/dot. You'll need to obtain focus and then minutely move the focus using the IR guide.

  • Thanks a lot for all the details. Beyond what value of exposure would you say reciprocity gets into the picture? – Bob May 17 '18 at 22:47
  • @Bob it depends on the film. I wasn't able to find a spec on it for SFX, but Delta 400's is here: ilfordphoto.com/amfile/file/download/file_id/1875/product_id/… They begin adjustments at 1/2 second. – Hueco May 17 '18 at 22:51
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    Bob, shooting with IR film is probably the most guess and check style of photography one could pursue. I'm usually the first to fan-boy out with the film, except maybe @JindraLacko...but with IR, I've gotta tip my hat to converted digitals. – Hueco May 17 '18 at 22:56
  • @Corey if IR feels like guessing game you should someday try UV :) there is hardly any documentation, and just one opaque UV pass filter, the BW 403. – Jindra Lacko May 18 '18 at 14:36
  • @JindraLacko - touché. For IR, I've been looking at LifePixel for a conversion. Problem is, I thought I'd get my 20D converted when I bought a 60D...then I got a sweet deal on the 5Dmk2 and thought about converting the 60...now I'm kinda thinking I might wait another few years and convert the 5Dmk2...oh well...off to shoot some SFX :-). – Hueco May 18 '18 at 16:58
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I have more experience with Rollei Infrared 400, which is "the other" IR film. Where I live it is somewhat cheaper than SFX, which tips the scale for a cheapskate such as I. So take me with pinch of salt.

I correct for 4 to 6 stops (I take a shot on each correction and pick the one I like more). In most cases five stops is about right.

I do IR landscapes, which look the best in bright sunlight (clear blue skies become pitch black and interesting - a dull white sky would stay dull white). My film is ISO 400, so the basic exposure is something like 1/500 at f 16. Adjusting it for 5 stops is 1/15 at f 16.

I do not recommend opening your aperture too much because of the focus shift of visible vs. IR light, so keep it f 16 and stick with sunny 16 rule. In your case (ISO 200) 5 stops adjustment will give you a baseline of 1/8 second - I suggest to bracket at 1/15 and 1/4 just in case.

This is still sufficiently fast time you need not worry about reciprocity failure - this starts to kick at about 1 second.

As for shadow detail: there hardly is any. This has to do not so much with the film, but with IR light. It does not scatter much, so shadows are very, very dark. Keep this in mind in your composition and stick to uniformly lit subjects.

Your highlights on the other hand get blown easily; a compensating developer helps. Pyrocat HD is my favorite, it has additional benefit of being rather fine grain developer. IR material tends to be more grainy than its ISO would suggest, so keep this in mind (and avoid Rodinal and the like).

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