RE: Newbie (UV photogrpahy)

[Jason Revell <jason.revell@xxxxxxxxx>]

B+Ws true UV filter is the 403 (Schott UG1), they however also make a 484which allows more visible light through and cuts off at around the 450nm
mark this might be more like what you are after?.  These will just screw
onto the front of your lens (no need for the Cokin filter holder).  I just
hope your lens does not to large a thread as the cost of these filters is
not that cheap and also not made in all sizes, (remember you might be able
to make use of a step down ring?).  These B+W filters might also take a
little while to come, I had to wait 6 weeks for our 403 filter.  Having said
that I am still waiting for a Wratten 2E that I ordered in December from
Kodak and I have been informed that they only ship the gels 3-4 times a year
now.

The 403 :
I would expect it would allow you to get some sort of a UV image when
screwed onto the front of your EOS camera. I have used it once on the front
of an old K1000 and did manage to get some image on Tungsten slide film.
The B+W filter (403) allows up to about 400nm (15%ish transmission), the
main limiting factor is what wavelength your coated lens block from and the
UV sensitivity of your film.  Exposures will be quite long, I would be
guessing full open for a few minutes but this will of course depend on what
film you choose to use.  Any idea's yet?

The 484 : 

You will definitely get an image with this filter as it appears dark violet
rather than near black as the 403 does.  This will of course record a small
portion of the visible spectrum, (do your insects?).  It will record the
same portion of UV as the 403 but with some added violet, it depends what
you want your results to reproduce.  The only other thing to remember about
this filter is the fact that it also transmits a reasonable amount of IR ,
so HIE may not be the best film if you were thinking of using that.


I hope this is of some help, if I can be of further help please just contact
me again,

Jason Revell
Photographic Technician
Conservation of Fine Art
University of Northumbria


		-----Original Message-----
		From:	Andreas [mailto:a0000613@xxxxxxxxxxxxxxxxx]
		Sent:	19 April 2001 13:30
		To:	INFRARED@xxxxx
		Subject:	Re: Newbie


		Thank you all for your comments.
		To Helmut:

		It is a EOS. Are you saying that my "modern" 50mm lens
system is useless
		for UV? If so, then I'd go through with trying to remove the
coatings
		before buying a new or rather an old lens system.
		 

		bhphoto.com have an assortment of B&W Black Glass Lenses,
some really
		cheap (~35$ for a 52mm). It says that 

		"Although this dark violet filter transmits a small amount
of visible
		light, it completely blocks wavelengths longer than 360nm."

		which is conflicting information, as I see it, since the
upper limit for
		our vision is usually given as 400nm.

		I'd like to know if anyone has experience with the B&W
filter.

		Thank you again
		Regards
		Andreas

		-- 

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