Re: [Leica] Filter Factors

[Mark Rabiner <mark@rabiner.cncoffice.com>]

Shel Belinkoff wrote:
> 
> Everything I've read, including the information sheet packed
> with my new filters, indicates that the filter factor for a Medium
> Yellow filter (Y2) is 2X, or 1 stop.  So, while checking my gear
> this morning I decided to check the needed exposure compensation using
> two Pentax spotmeters, the digital Zone VI modified meter and the
> standard, but calibrated, Spotmeter V.  Both showed that the needed
> exposure compensation would be about 1/3 stop more with the filter
> than without.  I metered off a white truck, the overcast sky, and a
> building. Always about 1/3 stop. Off some other colors there was a
> slight
> difference in the readings between the Zone VI meter and the standard
> meter, which is to be expected, but in no circumstance did either of
> the meters indicate the need for an additional full stop with the Y2
> filter.
> 
> I suspect this discrepancy may be due to the sky being overcast and
> there being less blue light for the filter to absorb.
> 
> Since I'll be doing some work with hand-held meters and manual
> cameras, can we discuss this situation a bit.  One thought that
> crossed my mind was to make the exposure readings off a grey card,
> which I'll try later when I'm outside and away from the computer.  Any
> thoughts on that idea.
> --
> Shel Belinkoff
> mailto:belinkoff@earthlink.net
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Instead of pointing it at the sky, Shel, try pointing at a grey wall so the
color of the object you are metering is not an effect.
An extreme example is if you meter green foliage or green anything though a red filter.
Well the red aborbs all the green so you'd be over exposing like a sun of a gun.
You've got to meter off a neutral non color Get the filter factor I'd think.


Mark Rabiner

Portland, Oregon
USA

http://www.rabiner.cncoffice.com/
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