RE: Filter/Speed/Meter

[Jason Revell <jason.revell@xxxxxxxxx>]

The Weston meters from my experience are not very good at IR metering.  Due
to the photo cell (selenium if I remember correctly) they have they are not
accurate in levels of low light.  They also have a different response to red
light, though as long as this stays constant it would not prove a problem.
So the meter you are using might be the cause of the problems, though I
would wait until their have been a few more responses to this question
before you give up!

I use a Minolta auto 3 (and sometimes a 4) with a 5 degrees spot attachment.
I then have a 87 filter that I can mount in the spot attachment for IR
metering.  Due to the different photo cell in these meters (Cds on the Auto
3) these give much more consistent and accurate results.  I do not have my
lists of ASA/film types/Devs to hand at the moment but it is a good method
of exposure, and I am sure others will forward theirs.

Hope this is of help

Jason

		-----Original Message-----
		From:	R. C. Lacovara [mailto:lacovara@xxxxxxxxxxx]
		Sent:	02 October 2000 16:04
		To:	infrared@xxxxx
		Subject:	Filter/Speed/Meter

		Folks,

		I see that you share exposure information by stating the
filter which you 
		use (often an 89B) and then the film speed. That seems
reasonable. But 
		sometimes it's not clear what you are using for a meter. I
suppose that 
		light meters are similar in the visible, but do they not
differ somewhat in 
		the IR?

		In any event, could someone tell me, for either HIE or Maco,
a 
		filter/speed/lightmeter combination?

		I have tried a Hoya R72 over my Weston III and IV, but
despite several 
		sources' claims that these meters are IR sensitive, this is
hard to see. 
		I'm trying to rig a better filter mount for one of my
Westons.

		Thanks,

		Bob
		R. C. Lacovara, Ph. D.				
		Electrical Engineer in Computer Science Drag and
		Principal Member of Technical Staff

		The Charles Stark Draper Laboratory
voice: 281 333 2132
		Suite 210
		2200 Space Park Drive
		Houston, Texas 77058

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