Howdy Shell... If the filter were perfect for the yellow band, then the passage of yellow through the filter would not be attenuated. Other colors, blue for example, would be severely attenuated. Measuring a wheat field ready for harvest (no sky) should show considerably less loss from the filter than a scene with a lot of deep blue, say my neighbor's car. Beyond this, the response of panchromatic B&W films is not flat and as I understand it is biased a little toward the blue side. If this is true, the effect of yellow on a typical scene would be greater than a flat response meter would indicate.
I always used the table and rated Tri-X at 200. (often less, as the film is more forgiving of over exposure than Underexposure.) Regards, Bob... -------------------- "Let us contemplate our forefathers, and posterity, and resolve to maintain the rights bequeathed to us from the former, for the sake of the latter. The necessity of the times, more than ever, calls for our utmost circumspection, deliberation, fortitude, and perseverance. Let us remember that 'if we suffer tamely a lawless attack upon our liberty, we encourage it, and involve others in our doom.' It is a very serious consideration that millions yet unborn may be the miserable sharers of the event." - Samuel Adams, 1771 From: "Shel Belinkoff" <[EMAIL PROTECTED]> > The chart that came with a medium yellow filter indicates that a 1-stop > adjustment has to be made when using the filter. However, checking the > exposure through the filter, using Pentax spotmeters, and the meters in > the MX and LX, I get at best a need for a �-stop correction, and > sometimes less than that. Of course, shooting with the filter attached > and checking the exposure on the film is in order, but I was wondering > if the amount of blue light available might effect the amount of > additional exposure needed. If, for example, the day is sunny, would a > greater compensation be needed than on an overcast day where there is > less blue light to filter? OTOH, wouldn't the filter reduce the light > getting to the meter by a certain amount regardless of the lighting > conditions? - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
