Archived posting to the Leica Users Group, 1997/12/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]snip It would be unreasonable to correct a 21 mm for i.e. infinity,=20 >if you need the lens's best properties at - let's say - between 0.9 m=20 >and 2.5 m. So, I think, that both the 28 mms, that I had, suffered at=20 >infinity from the correction to close distances.=20 > >Different, the infinity "lack" of the 1.4/35 asph M Summilux should have=20 >another reason. I remember Erwin Puts mentioning, that the 24 mm (I=20 >believe it was the 24 mm), he was testing some weeks ago, showed the=20 >same "behavior". Erwin suggested, that this might be a general property=20 >of aspheric lenses, but he wanted & needed some more investigations.=20 > >Different to my 2/35 Nikkor, the mentioned Leitz lenses have no floating >elements.=20 > >Alf Interesting discussion: I have a particular need for good infinity correction with fast wide angle-= to shoot the night sky, specifically the Aurora Borealis (AB). I have found= that the best approach is to use f/2 to f/1.4 lenses wide open with 200 to= 400 speed color neg. film for 10 to 20 seconds exposures. The AB can range= quite a bit in brightness. It seems the brighter they are the faster they= move which is good since I want to stop their motion. In addition to L-M, I= use N and have had their 35 1.4 lens for a number of years and have used it= for this purpose. The angle of view of 35mm lenses is good for capturing a= pretty good portion of the sky too, though I have seen absolutely= spectacular shots of the AB done with the C 24mm 1.4 lens (with a lot of= Cos to the 4th dropoff)(I understand that a new version has been released= in EOS mount). The guy who shot the 24mm used to work at the Geophysical= Institute in Fairbanks and got a little version of one of his shots= published in National Geographic (this is a few years ago, but less than 10= yr.) I have been thinking seriously about the 35 lux-ASPH for this purpose but= this discussion suggests that this might not be the best lens. The problem= with the N 35 1.4 is there is a lot of coma - the lens is comatose!!! Stars= (the short 10 to 20 sec. exposures resolve the stars as points) in the= center look ok, but those on the periphery look disturbing and draw= attention away from the AB. I also noted this on shots I took of Hale-Bopp= (multiple comets!!!- stars plus the real one). Maybe the original= ASPHERICAL or 35 lux would be better for this purpose?????????? regards Tom Thomas C. Kline, Jr., Ph.D. =20 Research Scientist/ Diving Safety Officer =20 Prince William Sound Science Center =20 300 Breakwater Avenue, P. O. Box 705 =20 Cordova, AK 99574, USA 907-424-5800 tkline@grizzly.pwssc.gen.ak.us http://www.pwssc.gen.ak.us/