Yes, the M* was a ground-breaking lens for Pentax in many ways. It is an astoundingly small and light lens for its aperture and focal length. The only thing it doesn't yet have (1981-1984) is internal focusing. The introduction of IF allowed Pentax to use a smaller diameter front lens group (the F* 300mm f4.5 is 67mm filter size instead of the M* & A* 77mm size) and also to cut the minimum focus distance in half (from the M* & A* 400cm down to 200cm). That minimum focus distance seems to be the only negative mentioned for the M* and A* 300mm, but that isn't really an issue if you are using it for astrophotography.
Here is an amazing recent image by Stephen Migol, taken with the A* 300mm and a K10D. This image is the result of 3 hours of integrated exposure time (stacked shots). http://www.flickr.com/photos/smigol/10015256316/ On Tue, Oct 1, 2013 at 9:00 AM, Zos Xavius <zosxav...@gmail.com> wrote: > BTW, fascinating to hear that the M*300 is so corrected. I expected 1 > ED element, not 3. > > On Tue, Oct 1, 2013 at 10:00 AM, Zos Xavius <zosxav...@gmail.com> wrote: >> That element is bad, but not bad enough to destroy sharpness. I bet >> there is certainly some loss in contrast on that lens. Also night >> shots or anything with point light sources in the frame would be very >> problematic IMO. >> >> On Tue, Oct 1, 2013 at 9:26 AM, Darren Addy <pixelsmi...@gmail.com> wrote: >>> While doing a little research on the M* 300mm I purchased from CollinB >>> I tripped across this amazingly abused A* 300mm (same optical >>> configuration). Don't look if you are squeamish about the condition of >>> your lens optics: >>> http://forums.steves-digicams.com/attachments/pentax-lenses/147886d1264764384-test-shots-300-scratchedlens.jpeg >>> >>> Here is the amazing part: Check out the images it still produced in >>> this condition: >>> http://forums.steves-digicams.com/pentax-lenses/165305-test-shots-300-a.html >>> >>> The main reason I decided to try the M* 300mm is for astrophotography. >>> You can get away with a lot of imperfections in daylight photography, >>> but pinpoint star images highlight every defect. The M* and A* 300mm >>> f4 featured 3 of the front 4 lens elements made of ED glass (although >>> marketing departments had not yet seized on the use of "ED" in the >>> lens nomenclature). Other elements are made of high refractive glass. >>> In fact, only two of the 8 elements are "normal" glass lens elements. >>> For a film era lens, it is pretty highly corrected for chromatic >>> aberration. >>> >>> 300mm is pushing the limit for use with the O-GPS1, and I'm not even >>> going to attempt it until I get the Arca-Swiss p0 purchased. It may >>> even have to wait for the purchase of a "real" equatorial mount that >>> can respond to auto-guidance (the purchase of which is a loooong way >>> off yet). But I couldn't resist snagging the lens when Collin offered >>> last Friday. It should be in my hot little hands on Thursday. >>> >>> -- >>> Nothing is sure but death and Pentaxes. >>> >>> -- >>> PDML Pentax-Discuss Mail List >>> PDML@pdml.net >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>> to UNSUBSCRIBE from the PDML, please visit the link directly above and >>> follow the directions. > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- Nothing is sure but death and Pentaxes. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
