Re: Tiny cameras for infrared

[Joe Berenbaum <joe-b@xxxxxxxxxxxx>]

At 21:36 18/06/97 +0000, you wrote:

>Before you make too many people happy: for HIE you almost certainly need a 
>manual camera, or one that allows easy ASA adjustment. I assume EIR 
>doesn't have an ASA label on the cartridge either.
>(reminds me of the picture of a HIE cartridge in ColorFoto 
>7/97....never seen one before, I have never developed it myself, I 
>only handled it in the dark....:-))

You can get DX coding labels that stick onto 35mm film cassettes for all ISO
speeds if your camera needs them, so you can set the ISO for these non-coded
films in a DX-only camera. Not that I would like to go that way myself. The
Minox 35ML and Olympus XA4 (and indeed the XA) will allow manual ISO
setting. With XA4 you just tape over the DX coding on the film cassette and
use the ISO setting control. The Minox 35ML and the Olympus XA are both set
by their ISO controls. So you can set the appropriate ISO and even bracket
exposures on all of them, with a bit of thought. I'm so impressed by
pocketability and 28mm lens of the XA4 that I ordered a second one today.
Then it will be a question of- which one gets the internal filter- the tatty
one or the nice one? Decisons, decisions...

>> 1] Has anyone used the Rollei 35/35S for High-Speed Infrared? And if so,
>> does the lightly dimpled pressure plate ever cause a problem with this >>
film?
>> 2] Can anyone state what degree of dimpling (on a pressure plate) causes
>> problems with High-Speed Infrared- or does any degree of dimpling at all
>> cause a problem?
>
>I believe in my previous Minolta 7000/9000 there was a slightly dimpled
>pressure plate, and in my current EOS-1 the plate is attached with two 
>pop-nuts, the top one inside the image area (otherwise smooth).
>
>> And one other questionm, while I'm here-
>> 3] Do behind the lens filters (ie in front of the film plane- just)
>>cause>> any focus shift or focus error, and if so, is this more likely or
>>less>> likely with wideangle lenses?
>
>The focus shift is caused by the lens and depends on what filter you
>use (ie which part of the spectrum, or the relative amount of
>IR....less shift needed with #25 than with #87B), not by the
>location of the filter.
>I haven't changed my focus correction since I use a #87C between the 
>film rails. But rest assured I still screw up a nice 200mm shot once in a 
>while when I forget to correct focus....8-(( 

I think we may be talking about different things. I didn't mean the focus
shift that happens with different colour filters and IR light due to the
wavelengths transmitted by the filter, which can happen with filters in
front of the lens. My concern was whether having an extra optical material
(the polyester filter) behind the lens, but just in front of the film, would
cause the image to focus slightly in front of the film plane, even with
normal daylight films. But now that I've thought about this, your behind the
shutter filter would demonstrate this effect if there was one. And those
pictures look in focus to me! All I need now are recommendations of the best
tape to use to stick polyester filters inside cameras. Any suggestions? I
thought some nice, non-gunky black vinyl electrical tape would be a good
idea. It doesn't leave a mess and it comes off when you want it to, but not
before. 


Joe B.


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End of Infrared-Digest V0 #69
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