Has anyone had any luck with cutting the fogging of Kodak High Speed Infrared film by either: - cutting the amount of IR emitted by the sprocket sensor - making the sensor smaller by filling in the hole with an IR opaque material

If someone from Canon is reading this, I'd be real curious why the design tradeoffs were so heavily weighted against the use of IR film in these cameras. It seems to me that by restricting the opening of the IR sensor to the upper half of the sprocket hole, and cutting the light output, the halo fog wouldn't intrude into the image area nearly as much.

On my ElanIIe, I get fog that extends about 7mm into the image area. Interstingly enough, the lower edge of the raised plastic block that the IR sensor is surrounded by lines up almost perfectly with the stripe along the upper edge of the film that has D-max. This line also happens to line up pretty closely with the edge of the image area on the film. (for those keeping score this is about 1.3 to 1.4 cm of fogged film - 7mm that is D-max in the sprocket area, and ~7mm that drops off in density dramatically 1-2mm below the edge of the sprocket holes; tapering off to zero about 1.3-1.4 cm from the edge of the film. Obviously this cuts the usable area of my negative down too far.

-- Scott Bartlett (rsb@spies.com), June 04, 1999

Answers

I don't have a fix, and I've never heard of one. I presume the reason Canon didn't really address the issue of IR film is that less than 1% of EOS users will use it, maybe less than 0.1%, so it's just not a marketing issue. IR capability won't get them many (if any) extra buyers!

My suggestion would be to find an used older body with mechanical sprocket sensing. The early Rebels are fine, as are the 600 series and RT bodies. Alternatively, Konica 750 is reported to be fine in the IR sensor bodies, though of course it is slower than the Kodak emulsion and has a more limited IR spectral sensitivity.

-- Bob Atkins (bobatkins@hotmail.com), June 14, 1999.