Re: B&W IE

[v.bromfield@xxxxxxxxxx (Vaughan Bromfield)]

At 3:40 PM 14/10/96, Robert Long wrote:

>|Bobbi posted here meter settings of around 2000. This sounds to me like =
>the
>|meter is *very* sensitive to IR! If the meter wasn't sensitive to IR,
>|wouldn't the settings have to be around 12 or 6 to compensate?
>|
>|Correct me if I'm wrong please...
>
>I'm afraid I must.  Let's say that the correct exposure for a given
>scene is f/8 at 1/250 sec. for an EI of 200 and that the meter has an
>IR-blocking filter that absorbs all but 10% of the red and infrared
>coming through the filter in use.  The meter will "see" so little of
>the light coming through that combination of filters (that on the lens
>and that on the metering) that it will claim a shutter speed of 1/25
>sec. will be necessary for correct exposure.  The only way to get the
>correct setting will be to advance the camera's EI setting to 2000.
>That will net you the correct exposure settings.

Bob

Thanks for the clear,
not-too-technical-but-just-enough-to-illustrate-the-point (NTTBJETITP)
explanation. I understand.

Another one of those "opposite is true" cases so often found in
photography, like increasing exposure when you meter highlights.

Again, thanks.

Vaughan



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Topic No. 21