Re: Focus corrected IR-filter (was: Another New Subscriber

["Steve Midgley" <smidgley@xxxxxxxxx>]

I have to admit that I was basically echoing the info in the Rollei
"Practical Accessories" publication. I used to manage a used camera shop
that specialized in Rollei and we were doing research on just how practical
some of these accessories really were. We did put a micrometer on one of
the larger size IR filters (Bay IV or VI, can't really remember) and did
find that it was very slightly thinner in the center if I recall. Not
exactly scientific in any case. Though the shop doesn't exist, the
inventory does - maybe I'll see if I can repeat my results and report back.

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> From: Willem-Jan Markerink <w.j.markerink@xxxxx>
> To: smidgley@xxxxxxxxx
> Subject: Re: Focus corrected IR-filter (was: Another New Subscriber
> Date: Sunday, December 08, 1996 7:56 AM
> 
> On  8 Dec 96 at 1:57, Steve Midgley wrote:
> 
> >     My equipment ranges from 35mm to 8x10 but my favorite camera for
> > infrared is the twin lens Rollei - I can use the Rollei infrared filter
> > (which is focus corrected for IR) and still be able to see to compose
and
> > focus. 
> 
> I once bought such a Rollei focus-corrected filter, but I be damned 
> if I can see any effect other than color (color equals a Wratten #89B, 
> see the IR-filter list on my homepage).
> All tricks and methods to prove it is concave or convex in whatever 
> direction were in vain. And I do have the Rollei manual/instructions 
> that once again confirm the focus claim.
> Yet Rollei Germany is also baffled when I ask them about it, they say 
> such a focus corrected filter never existed....
> It *can* be made they said, but would be quite expensive.
> Would love to get more info on this!
> 
> 
> 
> --
> Bye,
> 
>        _/      _/       _/_/_/_/_/       _/_/_/_/_/
>      _/  _/  _/               _/       _/  _/  _/
>      _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
>                      _/_/_/  
> 
> 
> 
>       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. 15