On 4 Dec 2016, at 21:51, Larry Colen <[email protected]> wrote: > > Igor PDML-StR wrote: >> >> Larry, >> >> I haven't done much of astro-photography, so, I am just >> curious: why focusing at infinity wouldn't work in this case >> (i.e. turning the focusing ring to the end of the range)? >> Is it just because the particular lens(es) are not designed or >> manufactured well for infinity focus? (E.g. they have "beyond infinity" >> focus at the end of the wring range.) > > Exactly. I've been told that "to infinity and beyond" is necessary for > autofocus, although that doesn't seem true for my FA77. I suspect that it's > just a lot less expensive to guarantee that a camera will focus past infinity > than to carefully calibrate to go exactly to infinity. I wonder how much > sample variation there is in registration distance between the mount and the > sensor, as that would also affect the "infinity focus point". >>
Owing to the curvature of spacetime it should be possible with that lens to photograph the back of your own head. But you'll probably have to wait until the day before yesterday to do it. B -- 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.
