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This question got me thinking. My IR experience is limited to SFX200 so...

If I'm using an IR filter, all wavelengths below 720nm will be cut.

SFX200 is sensitive to 740nm, while Rollei IR is sensitive up to 820nm.

So, in comparing the films with a theoretical scene, the SFX will be capturing a slim range of only 20nm, while the Rollei IR will be able to capture a larger range (100nm).

What differences should one expect to see in the final negative?

For example, would one show brighter foliage than the other? Clearer skin and darker eyes in portraits?...etc...


Possibly answered a part of this question already, but adding it to the question for confirmation by more science-minded folk:

This paper by UC Davis shows a rather extreme change in reflectance for healthy leaves between 700 and 800nm... enter image description here

Given this, the Rollei IR would most likely capture an overall "brighter"* looking foliage and should be able to do so at a faster exposure time than SFX...no?

* I realize that brightness is subject to exposure - what I'm thinking is, if there is, overall, more reflectivity to the subject, the whole area would thus appear brighter - similar to how a white T-shirt would compare to a gray T-shirt with white writing.

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A brief note on history of both films:

  • Ilford SFX 200 has roots in law enforcement - it used to be fitted in traffic cameras, together with IR flash, to capture drivers of speeding cars.
  • Rollei Infrared 400 has nothing to do with the famed brand of medium format cameras (it is produced by Maco of Germany, which acquired rights to Rollei brand after the company bankrupcy), but descends from Agfa Aviphot. It comes from a long and distinguished line of aerial surveillance films.

Both emulsions were optimized for surveillance, and using them for artistic purposes was a distant afterthought to their original makers.

I am personally a fan of Rollei, but I know some very fine photographers who have mastered the Ilford SFX.

In my humble opinion both emulsions are capable of very fine and in the end quite comparable results. Both are tricky though, requiring non standard exposure metering and negative development. My suggestion would therefore be to stick with the devil you know, and rather put your energy into tuning your process.

I am quite certain there is more to be gained by optimizing your process with your current brand (no matter which one it is) than by switching and starting anew.

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