On Wed, Oct 5, 2016 at 10:45 AM, Eric Weir <[email protected]> wrote: > >> On Oct 5, 2016, at 10:24 AM, Bruce Walker <[email protected]> wrote: >> >> What the manual largely lacks is any description of _why_ you'd want >> to use the features. So you need to scan the PDML and hope that you >> can spot that useful piece of information floating amongst the >> butt-nuggets of overly tight y-fronts and butch automobiles. >> >> I have the PDML to thank for my finally engaging back-focus, and >> discovering how useful the green button is for metering with vintage >> glass, among many other things. > > Glad to hear that others see it this way. As you say, the manual reads like a > shopping list. I certainly have the list to thank for educating me about my > equipment and using it to make photographs. > > So, though it’s not come up for me experientially, what is “back-focus”? And > it’s been a while since I’ve used a manual lens—until I started trying to do > action photography I wanted nothing to do with autofocus—but I don’t recall > ever using the green button. What’s special about it?
Eric, I should have said "back button focus", which is that AF2 mode that Stan mentioned where autofocus is engaged only by pushing the AF button and not by a shutter half-press. It's great for studio shooting, I find. And one of the programmable functions of the green button is to push on that little pin that old Pentax lenses have which closes the aperture leaves down. I think they call this stop down metering. When you press the green button it will stop down, take an exposure reading, and open up again. If you set the camera to Tv, then doing this will set the shutter speed as appropriate for your selected aperture on the ring. This has enabled me to get more use out of my vintage S-M-C Takumar 1.4/50 that I've got attached to my old K20D. The metering is not 100% accurate, but it's pretty close and good enough. -- -bmw -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
