Re: Newbie (UV)

[Otto Giesenfeld <otto.giesenfeld@xxxxxxxxxxxx>]

--On den 20 april 2001 11:49 +0200 Andreas <a0000613@xxxxxxxxxxxxxxxxx> 
wrote:

> 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 ;-)
>

I can see one point of using a real EOS lens for UV photography: Unless the 
autofocus sensor is insensitive to UV, you will surely be able to get 
correct focus without bothering about correcting for the unusual light 
wavelengths. However, this should only be a matter of increased 
convenience, as I assume that most (all?) EOS cameras let you use the AF 
system for focus control even with manual lenses lacking the appropriate 
electrical contacts.

Unless you will be doing fast action photography in UV and really need 
motorized focus, I think you will be better off with an old lens. 
Especially since the EOS system has the advantage of allowing for simple 
adaptors with no lens elements that give correct infinity focus with M42 
screw mount lenses. So, you could buy an old Pentax or Praktica lens, save 
yourself a considerable amount of labor, and probably get better sharpness 
than the Canon lens would be capable of after being taken apart and 
reassembled.

Good luck with your project,

Otto Giesenfeld
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