Re: Newbie (UV)

[Andreas <a0000613@xxxxxxxxxxxxxxxxx>]

To Clive Warren

"The U-V filter in the human lens has a yellow 
appearance and also absorbs heavily in the violet and blue. This 
filter is not present in the lens of cats, dogs and predators. They 
receive much of the U-V light that we filter out."

This is really a big problem for me, since I'd like to extend my vision
regions which exclusively belong to insects (and crustaceans with
compound eyes). However, their visual receptiveness has another peak
below 400nm, which mammals lack. That peak can be thought of as another
color (most insects lack the "color" red), while non-primate mammals do
not have color vision, if I remember correctly.

Can you give me any references to how much UV cats et al. can see and
actually use? I have lots of articles about insects, yet little about
that. 


ad Setup

The basic problem I have is that if I buy the filter to fit the
lens-system, I ought to be sure the lenses actually transmit UV.

The lens system I have now has few elements (though I am not sure how
many), it is a simple non-zoom thingy. Problem is, it isn't antique.
A technician at the biology department suggested to remove the lens
coatings using a metal polish (Unipol). That isn't difficult, only to
get to all the lenses, I'd have to take apart the whole thing.

Since I do not intend to use the 50mm apart from doing UV, I'll go ahead
with removing the coatings before trying to get an old lens as most of
you suggested. I'll let you know if I can pull that one off ;-)


The B&W 403 filter (-> Schott UG1) you suggested would work nicely, I
hope, and the 52mm that is the correct one for me (I think so) only
costs 36$ yet they charge 27$ more for shipment. In addition, 4-10 weeks
until they have it...

BTW has anyone experience with the Tiffen 18A? Altough I am not sure if
one can get it outside the US.

Thanks again
Regards
Andreas

-- 

    \  _.-'`-._     "I believe I have acted rightly in steadily
     >< DARWIN >    following and devoting my life to science."
    /  `-.__.-'                               - Charles Darwin
         L  L
*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************