Archived posting to the Leica Users Group, 2001/09/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The filter factor also changes throughout the day, depending on the temperature of the light. Some guides to filter factors list them as noontime and sunrise/set factors. Same is true for tungsten, etc. A yellow or orange filter has a lower factor near sunset. They also vary with type of film - panchromatic v. orthochromatic film. The Zone VI meter is calibrated to respond to light similarly to panchromatic film, so they claim that it responds properly when reading through filters. Although I have not tried it, they claim that you can use it to measure how much effect you are having through the filter, for example, on reducing the value of the sky with your yellow filter. But as Jim said, if you meter TTL, you do not have to worry about this stuff. Tom Schofield >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 > > -- > > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > >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/ >-- >To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html