Re: Infrared dilemma

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 10 Nov 96 at 20:13, WRG5534@xxxxxxx wrote:

> I've run into a situation that I don't understand.  Using Konica IR rated at
> ISO 32, with a #25 red filter, and a polarizing filter, all of my shots came
> out great.  Now, while using a 20mm lense, the frame corners are all clipped,
> resulting in a round exposure. This only happens with IR film.  Could it be
> that the extra filter at the front of the lense be the problem?  Or has it
> something to do with the thickness of the film? Willard Gill

Stacking filters with a 20mm, unless using special wide angle
filters (larger glass than usual for the same filter size), is a
sure way to get vignetting. 
You might try the Cokin-P system; on some 20mm's you can use pol's
and ordinary squares together without vignetting, provided you keep
the 'ears' on top and bottom of the frame in landscape mode.  

Other solutions are the wide angle pol filters from Heliopan; those
are the only ones that show a front filter thread as well (the wide
angle pol filters from B+W don't have it, although B+W does have
normal color filters in wide angle version, unlike Heliopan). Sit
down when inquiring for prices though, especially for the pol
filters.


--
Bye,

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      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]

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Topic No. 5