A test on a Nikon Coolpix 950 with IR

[Jason Revell <jason.revell@xxxxxxxxx>]

I hope this posting is of interest and not to long (apologies if it is), but
thought it might be of interest to the group.


Since there have been a few postings about this camera and it's IR ability,
I took a few shots this morning in the Studio with the various IR filters I
had to hand.  Although the subject matter is probably not the normal for
most members on the list, it does show the IR effect quite well and you can
see the differing IR effect the various filters produce.

The photo's are of a board with a carbon based, ink drawing.  Then various
pigments have been painted in squares over sections of the ink drawing,
simulating underdrawings sometimes found in artwork.  When it is viewed
under IR you can see the pigments behaviour to IR, both reflectance,
absorption and transmittance (hence the need for the underdrawing).

The filters used were; 89B,88A,R72,87,87C and a B+W 094.

Lighting was provided by two 200 watt tungsten bulbs at 1.4 meters distance.
This gave me a light reading on my IR filtered meter of half a second at f8
when it was set for Konica 750.  I have presumed this would be a similar
level of IR light to a sunny day here in the UK (though I have not seen one
of those for many weeks!)

All the pictures were taken in colour mode, then converted into b&w in
Photoshop afterwards so any colour cast could be seen and any noise
generated by the CCD under low light would show up better before conversion
to b&w.  They were also autoleveled as most, when viewed on the monitor,
were a little on the flat side.


Results from the 89B,88A and R72 were very much the same as you would
expect.  The IR effect was quite visible on board and stronger than I would
expect if taken on Konica/Maco film.  Also these filters produced a light
red colour cast, this of course is more a point than anything else as you
can set the camera to b&w mode.

The 87 gave a good IR effect very similar to our HIS photographs.  There was
no colour cast to speak of at all and no noise on the image that I could
see.  The only problem was that the camera could not focus through the
filter, so it had to be set to manual focusing, which incidentally resets
all your other settings you have made like switching off the flash (slightly
annoying if you ask me!)

The 87C filter gave a good strong IR effect and slightly stronger than HIS,
the film we normally use.  There was a very slight amount of colour noise on
the photo but once it was converted to b&w the noise was not noticeable (on
the monitor anyway!).  Of course if the level of IR is lower than this
situation it might prove quite different.  Also the camera was unable to
autofocus though the filter again.

The B+W 094 filter (filters out below 1,000 nm and normally lives on our IR
videcon as it's useless for IR film!).  The image was barely visible on the
Coloolpix's view screen and the camera was of course unable to focus again.
Once loaded onto the PC and autoleveled, you could see the image but there
was a large amount of noise.  Though once this was converted to b&w it just
showed as heavy grain (think heavier than over dev'd HIE in D19).  Image
wise you could see a very strong IR picture, but the 'grain' was, in my
opinion, to heavy to make the image of much use.

Unfortunately I do not have a web page set up yet (another project to get
done over Christmas!) that I can post the images on, but if anyone wants to
see them email me and I shall email then to you.  The 7 images (all the
filters and visible light) are 107K so they should not prove to large to
download I hope.

Jason Revell
University of Northumbria
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