Archived posting to the Leica Users Group, 2004/09/06

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Subject: Was Re: [Leica] Re: MORE THAN... R.I.P. ILFORD now Digital IR an d UV
From: deveney.marty at (Deveney, Marty (PIRSA))
Date: Mon Sep 6 18:59:29 2004

>I would be interested to know what the full spectral response might be as
>the IR effect of shooting and keeping only the red information works pretty
>I did try shooting through a Leitz IR filter (looked about the equivaent of
>an 87C- very deep red- and of course got zip, zilch, nada for my effort.

Most newer digicams have a filter over the sensor to eliminate IR and UV.
Shooting in UV has other problems I've outlined below.  Some of the older
Nikon Coolpix cameras made fantastic IR images with an 87 series filter -
obviously the filter was absent or cut in at a higher wavelength on the
older cameras.

>If the future is digital, think of the possibilities of shooting in the UV
>and Near UV spectrum

This is unlikely to be the case, unless some manufacturer decided to make a
dedicated UV digicam.  The main problem with `normal` cameras designed for
picture taking in daylight is that modern multi-coating and to a lesser
extent, some modern optical glasses, block UV effectively (yes, your UV
filter really is redundant ;-)  

>I am pretty sure that folks like astronomers already do this with the CCD
>they use- The Three College Observatory near here has published some really
>neat timed exposures (5 minutes!- sharp with no camera shake!) of deep
>objects outside the visible spectrum. I guess they are 'false' color, but
>they are simply beautiful. I can see why amateur astronomy is so popular!

Many fields of science requite IR and UV photography.  Archaeologists
routinely use IR photography to show detail in stone work and other
artefacts that cannot be seen under regular light.  Botanists and biologists
have realised in recent years that plants and animals often communicate and
use as recognition systems patterns of UV reflection.  Many insects and
birds can see into this region of the spectrum.

The lenses and filters used for this work are expensive and not very useful
for anything else.  UV lenses, in particular, need to be made of quartz
rather than glass and are not coated.  The Nikkor UV 105mm macro that was
available briefly was a very good lens for UV work, although the $5K
pricetag meant that the vast majority ended up in labs, rather than in the
hands of photographers.

There is some work done with this lens by Bjorn Rorslett here:

The best news of all is that an uncoated lens using old glass (like a 50mm
Elmar!) and film can make acceptable near UV images: in fact some of these special uses may keep
film alive (it's going to be hard to get a digicam to do what Kodak HIE can
- and it's already very expensive).