Re: BTFR filters (was: message in full, something wrong with my

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

On 11 Aug 97 at 19:07, Jaap Los wrote:

> Hi Willem Jan,
> Nikkormat EL and Nikon F 801 S (8008S)`
> I measured 24.05 mm with the gauge of my neighbour (he is a technician).
> I think I can neglect those 0.05 mm as the feelers of the gauge were
> made of plastic! I always thought, that these things had to be made of
> steel. 

Are you sure he is a technician?....;-))

> However stick to 24 mm. The depth was measured at 0.5 mm. I can
> hardly imagine, that a piece of foil (maybe the #87  0.1 mm?) will fit
> without damaging film and/or foil. Still I'm interested in having much
> more info about BTFR-business. On advice of one of the list-members I
> read an article written by Andrew Davidhazy on this subject. This didn't
> very much help as it doesn't describe the practical problems/hints
> sufficiently. Questions like: how to cut precisely, how to get the foil
> straight, how to stick with tape and which tape, how to avoid dust etc.
> are facts I still like to know. I could try with a #87 foil of 0.1 mm
> thickness. A #87C (0.4 mm ) seems to me too tricky as there is hardly
> any space left. Afterall I think, that in both cases film and foil will
> touch each other. What are the effects of this. 

The rails in my EOS-1 are only 0.5mm tall as well, and I have the 
0.4mm thick #87C mounted, fixed with ordinary transparant office tape 
from on top of the filter (sides) towards the body next to it. I have run dozens 
of film through it this winter, and it all went fine, no dust, hairs, 
scratches or peeling tape. I haven't tested it in extreme heat, and it 
might as well be that this tape will deteriorate over time. 
As for cutting precisely: you need a sharp knife and a straigth piece 
of metal as a cutting guide. 
And a flat surface is the only surface you will get with this 0.4mm
quality, it is quite sturdy, definately won't buckle....on the other
hand flexible enough to cut with scissors, but scissors are not
accurate enough for this application.

> A mounting inside the body behind the mirror and in front of the shutter
> looks to me a hell of a job if not impossible. In this case it must be a
> solid filter (a gelatine?) that will be clamped/fixed in the housing.
> You will never get it fixed with a piece of tape.

It seems a nerve job to me too, but with double sided tape and a 
vacuum suction device one should be able to mount it.
And I think Andy has succeeded in this procedure once, right 
Andy?....;-))
The largest risk to me seems the shutter coming down....a real 
mechanical T setting would be my preference....8-))

 

- -- 
Bye,

Willem-Jan Markerink


      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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