Re: taking IR pictures in the dark

[cameron shaw <cameron@xxxxxxxxxxxxx>]

On Thu, 13 Nov 1997 16:17:40 -0800 Thomas "Hank" Hogan wrote:

> From: Thomas "Hank" Hogan <flzhgn@xxxxxxxxxxxxx>
> Date: Thu, 13 Nov 1997 16:17:40 -0800
> Subject: Re: taking IR pictures in the dark
> To: infrared@xxxxx
> 
> Once I burned up a Wratten 87C infrared gel filter -- I put it inside a 
> microscope illuminator and fried it!  There was nowhere for the heat
> generated from the absorption of visible light to go.
> 
> On a flash unit that I use for photographing crepuscular animals by
> infrared
> flash, I've glued the 87 C gel to the glass of flash unit and reinforced
> the
> edges with multiple layers of black plastic electrician's tape.  Another
> filter
> I've used is made of fragments of 87C gels taped together overlapping
> with
> Scotch brand tape over a piece of unexposed E6 leader.  I use this one
> on
> an Olympus T32 flash.  I've had to use all kinds of things to prevent
> light
> leaks.
> 
> I am intrigued by the 87C polyester filters mentioned by W.J.
> 
> Hank Hogan
> 
> Rolland Rainbow Elliott wrote:
> > 
> > I'm going to try to take some IR pictures in very low light to total darkness
> > situations, and need some advice.
> > 
> > I bought a Kodak 87C Wratten Gel filter and covered the flash head of my
> > SB-26 flash with it.  I pushed in the red "test flash" button to see how much
> > visible light I could see.  However when I did this the gel litterally popped
> > off the flash head, and was slightly burned.It wasn't burned all the way
> > through, but I bet another ten or so flashes would destroy the filter.
> > The gel is now very wavy and ruined.
> > 
Hello,
	I had the same experience and discovered that an air space of about 2cm 
between the flash head and the filter is necessary, to allow dissipation of the non 
infra red energy that is absorbed by the filter and converted to heat. If you stick the 
filter against the flash head it will melt!
Cameron


*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************

------------------------------

End of Infrared-Digest V0 #296
******************************