Re: Infrared Flash photos, anyone?

["Gordon J. Holtslander" <holtslander@xxxxxxxxxxxxx>]

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Hi:

Years ago I helped an friend with his engineering reseach.  This is really
UltraViolet rather than infrared photography.

He needed to take pictures of tufts of string on a model in a windtunnel.
The tufts had to be very small - so small that they would not be resolved
in a normal photograph.  We used the flourescent microtuft technique.

We loaded the camera with normal (but fast) B&w film.  We put a U.V
blocking filter on the lens of the camera.

We made flourescent microtufts, by coating thread with the dye/ink from a
highlighter pen - a flourescent material.

We put a daylight blocking-UV passing filter on the flash.  The flash
would only "generate" UV light.

When a picture was taken the flash would produce U.V light.  The
microtufts would flouresce (convert UV radiation to visible radiation).
The film would only capture the image of the flourescing tufts because
they were the only source of visible light.  Anything that was not
flourescing was reflecting UV light - which was filtered out.

I have long forgotten the details - ie what filters were used etc.  IT is
an interesting technique.


The gist of this is that an electronic flash does produce "light" outside
of the visible range.  IR and UV.


On Thu, 15 Jan 1998, Anthony W. Maw wrote:

> Hi all:
> 
> Electronic flash produces infrared output in addition to visible light.
> 
> Has anyone else tried taking photographs with infrared flash?
> 
> I once taped a piece of 87 gel (visible opaque, infrared only) over a GN 40
> flash (Minolta AF4000) and shot with a 50 mm lens 1/250s on HIE.  When the flash
> fired there was a slight but barely noticeable red blink through the 87 gel.
> The photographic subject was myself (ugh) standing about 2 meters away in a
> COMPLETELY BLACK room.  (I could not even see my hand in front of my face)
> 
________________________________________________________________________
Gordon J. Holtslander			112 Science Place
HOLTSLANDER@xxxxxxxxxxxxx		Department of Biology     
URL: http://duke.usask.ca/~holtsg	University of Saskatchewan
					Saskatoon, Saskatchewan
Tel (306)966-4433			S7N 5E2
FAX (306)966-4461			Canada
________________________________________________________________________

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