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cshimokita
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Extended Red Sensitivity Film - "repost"

It's a quiet time of the year with every eye on the happenings in Basel, so I thought I would dig out an old thread from August 2014 and repost the photos taken with Ilford SFX 200, a B&W film that has extended red sensitivity (up to 740nm) using a R72 Infrared Filter... as usual it was the Nikon F3P and AI-s 50mm f/1.2

Exposure...  The Ilford SFX 200 data sheet recommends shooting in bright sunshine. The R72 filter factor depends on the film's ISO rating and lighting conditions... from different articles I found that a recommended exposure starting point would be to meter at ISO 6.  With the aforementioned film my test results were as follows:

A) in shaded sunny conditions meter at ISO 3 (i.e. 6 steps)
B) in bright direct sunshine meter at ISO 12 (i.e. 4 steps)

Even at that, there was some variance, so the above is only a guideline and bracketing is recommended.

A word about focusing...  When working in the IR range you need to focus slightly different than you do with visible light... on older lenses there might be a dot on the distance scale... the idea is to focus using visible light and then adjust according to the position of the dot.  It's impossible to focus a SLR with the R72 attached... so the process was to remove the filter during set-up, composition, and [manual] focusing... even with bright sunshine my exposure times were in the range of 1/15 or 1/8 second... a tripod is recommended.

Development... Ilford SFX 200 is a standard B&W film and requires no special handling during development. I mention this as the staff at my local development drop-off point were not familiar with the film.  SFX 200 costs about USD 12.00 per roll (USD 13.50 in 2019), so it's a bit expensive...

Thanks for looking,
Casey

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