Efke IR820 Film

This is an infrared film with sensitivity out to 820nm. The infrared look is most apparent if a strong low-pass filter, e.g. Hoya R72 or equivalent is used.

Metering

See metering for infrared.

The optimal ISO is actually 1.5 to 2 but the 1s exposure at f/16 takes into account the severe reciprocity failure of this film. If you want to make a shorter exposure (e.g. f/4) then you should use this higher ISO and therefore a shutter speed of about 1/25. For longer exposures (e.g. f/32), consult the reciprocity failure table in the datasheet.

HD Curve

The film has a very long toe and dramatically up-swept HD curve, which means that it retains excellent (though relatively flat) shadow detail and has bright, glittering highlights with excellent contrast.

IR820 Aura

The Aura edition of this film lacks the anti-halation backing, which means that highlights will glow due to scattering of light within the film. This results in the loss of some highlight separation (the "glitter") but is a beautiful effect in some situations. It is most apparent in smaller formats (35mm) but is only slightly perceptible in medium format, e.g. 6x7.

Development

This is a grainy film with poor resolution and therefore benefits from a solvent developer. While you can develop it in Rodinal, the result looks like 40-grit sandpaper.

I prefer XTOL at 1+1 for 15:00, which helps with the long toe. D76 and XTOL stock are also good approaches (more solvent, smoother grain) but susceptible to unsightly dense spots due to clumping in the concentrated developer stock.

References

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