Infrared Film and OM?

[dean_tyler]

Is anyone shooting IR film with OMs. I have read that that the

dimples on the film pressure plate in the OMs creates a problem with

IR film in these cameras. Is it true?

[mark_bouquet1]

IR film has no anti-halation layer on the film base, so light can and will bounce back from the base into the emulsion to flare the highlights. This is part of the charm of shooting with HIE. The dimples on OM pressure plates can act like little Newtonian reflectors to focus that bounced back light, so the pattern of the pressure plate becomes visible on the film. That's the story I've heard anyway. My experience with HIE only extends to about a dozen rolls, but I've never had any such problem. At least I haven't noticed it.

 

There was an urban myth that was later verified, I think by John Hermanson, such that years ago Olympus America special ordered a few non-dimpled pressure plates for OM users who used a lot of HIE. Supposedly there were only a few made, like twenty I seem to recall, which were slowly distributed until they went out of stock.

 

Just go shoot infrared with your OM and don't worry about it.

[lex_jenkins]

Hmm... all this time and I'd never noticed that film pressure plate before. They're actually more like rows and columns of tiny pinpricks than dimples. Definitely not smooth like my Nikons, tho'.

 

This is interesting enough to make me want to try IR film again, which I haven't done in about 30 years. It'd be interesting to see whether the pressure plate surface really does affect the IR "bloom".

[simon evans.]

I have exposed Kodak HIE infrared without any problems (examples: <a href="http://www.photo.net/photo/465683">1</a>, <a href="http://www.photo.net/photo/591475">2</a>), although I have read of a couple of people who experienced this. Note that it only occurs with HIE, as it does not have an anti-halation backing. Konica, Maco and Ilford SFX200 films will not show this problem. A few years ago Olympus USA were able to supply a small number of smooth pressure plates, but I suspect they are as rare as hens' teeth.

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You can cover the plate with 120 rollfilm backing paper. Some suggestions at <a href="http://zuiko.sls.bc.ca/swright/archives/1999/msg12533.html">http://zuiko.sls.bc.ca/swright/archives/1999/msg12533.html</a>

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I suggest you try a roll and see if it affects your photos.

[ecarter]

The OM pressure plate can indeed cause problems with Kodak HIE - while I have gotten good results, on shots where I have larger areas of the same tone, I have noticed the dimple pattern. I've heard of some people taking a bit of old photo paper bag and covering the pressure plate of your camera with it to shoot HIE - I don't trust this method, but it might be worth trying.

[erik_gould1]

Yes indeed, the pressure plate can cause problems. I had the plate on my OM-3

changed out for a smooth one for just this very reason. I was working on a project

shooting with Kodak HIR and the dimple pattern was very noticeable anywhere there

was an area of even tone, like a sky.

[kieran_hamill]

You can't be sure it's the OM plate to blame. You could make good money selling the shots as capturing a Venusian invasion fleet using their infra red cloaking device. Or a flock of starlings re-enacting scenes from the Dambusters.

[Aoresteen]

Interesting. Since I have a spare OM1 back maybe I can swap in a Pentax or other pressure plate. Seems to me that the OM plates just pop out. I'll take a look tonight.