I recommend you look at some texts on UBV system used in 
astronomy. This is not so easy to just convert. You will 
need to know a little about the light to say how many 
lumens correctly. The reason is that your meter may not 
be linear for all wavelengths and different wavelengths 
generate different amounts of warming. Most meters are 
temperature sensitive so have some degree of dark current.
Your meter will work fine for simpler photographic measurements,
but for getting the correct flux density, you may need some
filters to indicate what the black body curve looks like....
I am not really an expert with these things, but I promise 
you will find what you are looking for in any astro photometry 
text along with relevent equations... 

Dominic 


On Mon, 11 Jan 1999, Royce Bair wrote:

> I have a nice, $400 Minolta IV exposure meter (for photography) that
> will take incident light readings (both for ambient and flash).  The
> readings it gives are super accurate for film/camera exposure settings. 
> However, I have a need to convert the f-stop and shutter settings to
> either "footcandles" or "LUX" levels.  I need this conversion for some
> scientific testing I'm doing.
> 
> Let say, I set my meter to an ASA or ISO of 100, and my meter gives me
> an ambient light reading of for a camera exposure setting of F8 @ 1/30
> second -- what would be the level of LUX or footcandles of light that
> has fallen on my subject?
> 
> Does anyone know how to get this information?  I don't want to buy a
> light meter that gives these reading in LUX or footcandles, when I
> already have a very sensitive meter.
> 
> BTW, I know how to convert between LUX and footcandles.
> 
> Royce Bair
> [log in to unmask]
> Stock Solution (a photo agency):
>   http://www.tssphoto.com/
> 
> 


Cheers,



Dominic

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East  17 48' 10"

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