The M and A * 300mm lenses look good enough for astrophotography IMO based on that image. I love the size of the M actually. Very nice and compact.
On Tue, Oct 1, 2013 at 10:18 AM, Darren Addy <pixelsmi...@gmail.com> wrote: > 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. -- 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.
