Re: IR light meter

[Stan McQueen <stan@xxxxxxxxxxx>]

At 12:31 AM 03/01/2000 +0100, you wrote:
>On 26 Feb 00 at 11:06, Foamb wrote:
>
> > Has anyone tried this? I'm thinking of using a Gossen Luna Pro digital
> > and trying it out unless someone has experience with the disassembly of
> > meters and can recommend a better choice. The pentax digital spot was
> > mentioned but required considerable effort to disassemble and modify,
> > not to mention that they aren't exactly cheap.
>
>I believe this one is named Sixtomat Digital (F) in Europe, and it is
>exactly what I did to mine....cut a square piece of #87C filter, popped it
>into the sliding rail that also holds the incident dome, and it
>now neatly reads the correct ASA values for HIE whenever I want it.
>
>The only boring thing is that on a bright sunny day, it *always*
>reads 1/60s @ f8....so I hardly use the meter anymore, while running
>brackets of 1/60s @ f5.6-f11....8-))
>--
>Bye,
>
>Willem-Jan Markerink

I tried this with my old, non-digital, Gossen Luna-Pro. On the low-range, 
you can indeed look into the meter and see the diode. On the high-range, 
there is a filter, presumably a neutral density filter, that slides over 
the opening. I slid the incident dome off to the side and covered the 
aperture with an 87C gel. On a bright sunny day I got nothing on the high 
range, but did get a meter reading (EV10) on the low range. I thought maybe 
I had something until I tried it again, replacing the filter with my thumb. 
I got the same reading! So either my thumb is equivalent to an 87C or what 
I am seeing is the dark current reading. I suspect the latter, especially 
since I get the same reading with the 87C pointed toward the sun as with 
the 87C pointed toward an incandescent lamp. Does anyone know what 
semiconductor is used in the photocells?

Stan

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