On Sun, Dec 03, 2006 at 12:46:26PM +1030, Peter Loveday wrote: > >> * The MTF programme line still refuses to use all apertures on my primes > >> (ie, no F1.4 on the FA50/1.4) > >> > > > > That's what MTF prog. should do. It is choosing the aperture based on > > what gives the better (i.e., sharper) result. The MTF value for F1.4 > > is low so the camera it is going to avoid this setting and stop the > > lens down for a sharper result. If you want the camera to include > > F1.4 then switch out of MTF based prog. > > I'm quite aware why and what it is trying to do, I just disagree with the > decisions the camera makes (well, the engineers made) on this, basically > that either: > > * ISO 1600 at F2 is better than ISO 800 at F1.4 on this lens > * 1/15 at F2 is better than 1/30 at F1.4 on this lens. (SR changes the > values here, but the principle remains the same) > > Either of which I think are wrong.
In that case you should turn off auto-ISO, and/or take the camera off the MTF program setting. The engineers haven't decided that 1/15 at F2 is better than 1/30 at F1.4; they have just provided a program line which will allow you to declare that MTF is the most important thing. But only if you select that program line. Complaining that MTF won't use the widest aperture is about as sensible as complaining that Tv won't adjust the shutter speed. MTF, like Av, Tv and Sv, is just one of the tools available. It isn't a universal panacea - it's just one form of automation. You have to know how it will behave, and choose the right tool; expecting the camera to think for you is unrealistic. There are other program lines that don't use MTF; when you are shooting in low light, and care more about shutter speed than the resolving power of the lens, you should use one of them. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
