Hi Bill, Yes, you're making sense, although vaguely.
Let me say that, in practice, with TTL metering, this subject is almost moot. I say almost because, as you've noted, there are numerous variables, but how great a role they play is open to speculation and testing. But, here's what I've found using both B+W and SMC Pentax medium yellow filters. Neither, no matter which of the five meters I used, shows a full stop difference in exposure as indicated. At most 1/2-stop more exposure is called for, and often it's closer to 1/3-stop. While it's sometimes hard to tell with any precision exactly what the exposure differences are with the LX, ME S, and, surprisingly, to a lesser degree with the MX, in no case is it a full stop, or even close to a full stop, per the meter readings. Kodak says that different factors should be used for daylight and tungsten, so it may well be that different factors might be used for different types of daylight - bright sun, cloudy and overcast days, deep shadows, etc. Thus far it appears that the metering variations are slightly different in different light - about 1/3 stop in shade or overcast, and 1/2-stop in sun light. Different areas of the sky return slight differences, depending on the amount of blue that's visible and the position relative to the sun. My conclusion, thus far, is that reliance on the stated filter factors, or using a TTL meter, will not always result in the ideal exposure, and that considerations for the type of light is a prime concern. Of course, if one shoots with a "close-enough-for-government-work" approach, the stated filter factors or TTL metering indications may be acceptable, and they may be ideal for certain emulsions. But for careful, critical exposures, a good understanding of how the filter behaves in different light and with different films, may be required, i.e., making a set of test exposures as one does when using a new film for the first time. William Robb wrote: > > ----- Original Message ----- > From: "Shel Belinkoff" > Subject: Re: Using a Yellow Filter > > > I understand that, but let's get back to one of the original > > questions. If there is less blue in the light, which is what, > > in essence, a yellow> filter prevents from reaching the film, > > would the filter factor change? > > It would seem logical that it would, but I am not so sure. If > the ambient light is already -blue, then the exposure factor > would change based on that colour deficiency (the combination of > meter error and film speed shift necessitating the adjustment), > but the filter factor should stay the same. > I think the exposure adjustment in the situation you describe > would be filter factor + exposure factor = exposure adjustment. > Am I making any sense here? -- Shel Belinkoff mailto:[EMAIL PROTECTED] - 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 .
