I made some critical focusing tests at one time, using a 105mm lens @ f/5.6 on the LX with the refconverter M, which allows for 2X magnification. With the camera on a tripod, I very carefully focused on the eyes of a nearby piece of sculpture from a distance of about ten feet or so. I then flipped the magnification to 2X and was surprised to find that the focus could have been more accurate.
However, looking at 8X enlargements, I could not see any difference in sharpness from focusing at normal magnification and at 2X magnification. That doesn't mean there'd not be an observable difference at greater enlargements, or at a wider f-stop. Perhaps a better test would have been to focus on a one dimensional object, but I don't usually photograph such things. Fred Wasti did a DOF test using a yardstick set an an angle, and with a nail placed in it. He focused on the nail and was able to determine to some degree what the DOF was for a given lens/aperture setup. A setup such as that would, I think, be a good test for focusing accuracy. "Paul F. Stregevsky" wrote: > > Since mounting a 2X flip-up magnifier to my KX, and another to my Super > Program, I've been amazed how it has helped me improve my focus, even for > longer lenses. I now regard it as standard equipment. -- Shel Belinkoff mailto:[EMAIL PROTECTED] http://home.earthlink.net/~belinkoff/ http://home.earthlink.net/~belinkoff/darkroom-rentals/index.html - 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 .
