Re: filters

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

On  3 Jul 98 at 13:00, p j geller wrote:

> I recently got a B+W 092 filter .
> Before that I used a plastic ir filter made to go over
> an ir light source. 
> It is possible to view a scene thru both although it is quite dark.
> 
> The  092 does not show white folliage.
> The plastic filter does.

What kind/brand/type of filter is this?
 
>  Is there a glass filter made by B+W that allows
> one to view the Wood effect?

Not really.
I have found that while #89B is too light, #88A is too dark.
Yet exactly inbetween there is a color that gives a more than decent 
Wood-effect....provided that you shade your eye from stray light 
completely.
Oddly enough my ancient Wratten brochure does mention such a 
color....#88 (not 'A')....with the even more interesting description 
'as used by Prof. J. Wood'....
I discovered this optimum color by accident, with a batch of wrong 
colored IR filters in Cokin-P size (custom made stuff).
Since then I also found a matching gelatine (not from Kodak....they 
only make #87C and #87 currently).

I have been pondering about fabricating a viewing filter with a 
rubber eye socket (against stray light), but that project stranded in 
favor of other projects (of which I have far too many at 
hand....;-)).



- -- 
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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End of Infrared-Digest V0 #641
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