Kodak, the film company use to have a how to series that covered this, see
a pro photo store

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/