Archived posting to the Leica Users Group, 2004/01/09
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]To Akhil and Lee: Yes, Lee, when I find the time there will be a VIEWFINDER piece about the tests; also of the pre-ASPH and the first 8-glass 35/2 Summicron and the 35/2,8 Summaron. Since this is the Leica USERS Group, let me agree up front with Ted, B.D. and a myriad other LUG friends who have consistently said: "use your equipment to take photographs. If your lens produces what you want, you should be happy." As many of you know, that thought process is exactly what led me, a good number of years ago, back to the DR/Rigid Summicron as my main user 50, after having used the successor 50/2 Summicron (11817) and, briefly, the current 50/2 (11819 et seq). Most of my photography is at f/4, 5,6 and 8. When I need speed, I use the 50/1,4 Summilux. And at those intermediate apertures, in my opinion the DR/Rigid produces images that most please me. Not only in b+w but especially on Kodachrome, my most used color film. Precisely because I don't typically need the speed, like our dear friend Steve Lehuray, for me the old 35/2,8 Summaron produces marvelous images approximating the image-making of the DR. That actually was my primary motivation in setting up these tests: comparing the Summaron with the 8-element and the pre-ASPH 35/2 Summicrons. Then I said to myself, having driven all the way to Cambridge, while there, if they will let me, why not test the DR/Rigid 50 with Alpa's legendary 50/1,9 Macro-Switar. So we did. Akhil asked: > > What light source did you use and did you check for chromatic abberartions and light fall off? How the EROS test equipment works is far beyond this non-techie. But I do know that we tested with a visible white light source. We did not test with color filters so no test for chromatic aberrations. The machine uses a light slit aimed at the lens. It was collimated only for infinity. This is a fairly lengthy process, setting up each lens, focusing, then testing (inputting to the computer) at each aperture from initial to f/8 (we didn't stop down further since on these lenses diffraction begins seriously to affect optical performance after f/8) and then testing on-axis, at 12mm off-axis (the near edge) and at 18mm off-axis (the far edge). And remember, we were testing five lenses. I couldn't ask Roy Youman, the fellow at Optikos who did the testing, to spend any more time than the several hours we already did. > Were you able to test a current Summicron M or R at the same time? No. Seth LaK 9 - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html