Re: Flourescent Lenses

[ANDPPH@xxxxxxxxxxxxxxxxxx]

> I noticed, about a year ago, that about half my lenses flourese in UV light.
> There seemed to be no correlation with lens age or quality. It crossed my 
> mind that lens flourscence, not film sensitivity to UV, could be the main 
> reason to use a UV filter.

Some camera lenses will fluoresce when subjected to UV radiation. If you are
trying to do reflected UV photography this can be a pain since it will cause an
overall fogging veil over the image. Placing a UV absorbing filter over the
lens will eliminate the fluorescence but also the UV which you are trying to
record.

<snip>

> >Would an IR image be sharper if there were
> >a UV filter placed before an IR filtering lens?

UV and IR are different things. Placing a UV absorbing filter over a camera
lens while doing IR photography in my opinion would not contribute any
improvement in lens preformance while trying to do IR photography. Such
improvement is not noticed generally while doing "light" photography. Further,
once you place an IR transmitting and light blocking filter over the camera
lens you are already blocking the UV since IR filters generally absorb not 
only light but also UV.

hmmmm ... finally ... what do you mean by UV filter ... one that blocks UV or
one that transmits it? This is a "problem" we seem to encounter since as far as
I know we camm every filter by the wavelengths that they transmit EXCEPt the UV
filter which can either be a UV blocking (2E) filter or a UV transmitting (UV
transmitting) filter.

regards,

Andy  o o  0 0 o . o  Andrew Davidhazy, Imaging and Photo Tech
       \/\/\/\/\/\/   http://www.rit.edu/~andpph  716-475-2592  
________|        |____________________________________________

                  
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End of Infrared-Digest V0 #787
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