Re: Filter Recommendations?

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

On  1 Oct 96 at 21:22, zoe paddy johnson wrote:

> 
> Where is a good place to buy filters?  by mail order, preferably with a 
> web site?  
> 
> Assuming I want to take pictures of birds in both near UV and near IR 
> *without* any visible light passing through to the film, which filter 
> or combination of filters would you recommend? which brand and number?
> (like wratten 18a or B+W 403)

Mmm....a problem I could imagine with the Kodak Wratten 18A is the 
fact that is only available in square sizes, not in screw mount rims.
The B+W is an uncoated filter btw, seems to be inherent to this kind 
of glass. 

> for UV?
> for IR?
> for looking for fluoresence in the feathers which would require 
> eliminating IR and UV and making sure only visible light makes it to the 
> film?

Well, UV-block filters can be found in any shop, just pick a brand
name, not the bottom of the line el cheapo's. Blocking IR can be
done with the B+W 489 or Wratten 43/44A, or you pick a film that is
not sensitive to IR (on one hand you should stick with one type of
film to eliminate as much variables as possible, on the other hand 
you might use several films to get as much color data as possible)

 
> I found a used spiratone violet filter at the used camera store; 
> would using it with my red filter (#25) begin to give a little bit of 
> idea as to what is UV is being reflected (not fluoresence)?

I think the fascinating effect only starts when it is *difficult* to 
look through. If at first sight it doesn't appear as a black filter 
(like the IR colors 89B and 88A do), then it probably passes to much 
of the visible spectrum to be effective. You shouldn't be able to see 
much through it at an overcast day either.... 

PS: have you checked surplus (scientific) microscope/telescope shops?
The only UV-pass filters I have seen in real life were microscope 
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. 13