Assuming you're using Kodak High Speed Infrared (HIE), the most
popular infrared film:
So what do I need to know to
not fog the film,
Load and unload in darkness for maximum safety. But
realistically, brief exposure to darkroom safelight doesn't fog
more than a frame in from the leader in my experience.
get in focus images
Either keep your depth of field very broad, or correct the focus
to the IR spot on your lens. Personally, I usually rely on depth
of field, it's simpler and faster. f/8 is usually more than enough.
and maximize the dramatic affect
of this film?
Deeper IR filtration makes the IR effects more dramatic, e.g. a
29 or 70 red gives more impact than a 25 red, and a
visually-opaque 87 or 87C has even more impact than the visible
red filters. Shoot in bright daylight for maximum IR effect.
My personal exposure preferences, assuming normal development in
D-76 stock: (I print these up the size of film box tops and stick
them in the holder on the OM-1 that I have dedicated to IR work.
It has an 87 gel mounted internally, between the film rails, so
that I can compose through the lens without constantly mounting
and removing the filter.)
HIE w/87 Gel Filter
Direct Sun 1/60 @ 16
Hazy Sun 1/30 @ 16
Light Cloud 1/30 @ 11
Moderate Rain 1/15 @ 8
Thunderstorm 1/8 @ 5.6
HIE w/25 Red Filter
Direct Sun 1/125 @ 16
Hazy Sun 1/60 @ 16
Light Cloud 1/60 @ 11
Moderate Rain 1/30 @ 8
Thunderstorm 1/15 @ 5.6
Bracketing is not usually needed if you rely on Sunny 16. Most
light meters are not reliably useful for IR, so if you're
metering with the deeper filters, you'll need to bracket more.
You may find in some situations that the dimpled pressure plate
of an OM-1 produces a pattern of hot spots on the negative.
Without an anti-halation layer, the film is sensitive to IR
reflected back off the pressure plate. If this bothers you, wrap
the pressure plate with backing paper from 120 film.
HIE is useful over a much wider range of exposure indices than
most people imagine. Kodak's old Publication N-1, Medical
Infrared Photography, included a special version of the data
sheet with CI from 0.5 to 1.35 depending on D-76 development
time, see http://www.phred.org/~josh/photo/HIEcurves.jpg
http://www.phred.org/~josh/photo/IR_exposure.html has some
examples at EI 60 through EI 500, all using 29 red filter and
D-76 development.
Except where noted otherwise, most of the photos at
http://www.phred.org/~josh/photo/ir.html are taken with my OM-1.
--
josh@xxxxxxxxx is Joshua Putnam
<http://www.phred.org/~josh/>
Updated Infrared Photography Gallery:
<http://www.phred.org/~josh/photo/ir.html>
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