Archived posting to the Leica Users Group, 2001/05/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> 1. When you are tesing a 21mm lens, is there a customary distance >(say, some multiple of the focal length) at which you check for fine >detail rendition? Usually, I shoot at a skyline with varying distances, >and the way I judge lenses is by the smallest thing (like, say a facade >brick or a limestone caulk seam) that comes out. This seems to have >failed me with 21s, since it seems that what I normally use to check >overall quality are now smaller than film grains. I used to frown upon people shooting newspaper pages for lens testing, but I have to admit it has one advantage: results are comparable. To make them comparable, also between different focal lengths, always shoot at a distance of (say) 50 times the focal length. The newspaper page will then be the same on all negatives irrespective of what focal length was used. I found 50 times a practical figure, I can do the shots indoors even when I test a tele. Using a factor of 100 times and a 135 mm would take a house bigger than mine. But shoot some real life scences too! > > 2. For people who heavily shoot 21s, is the game just to focus on >something in the foreground and let everything else fall in? I am >beginning to get the idea that slavish devotion to focusing at infinity >wastes the DOF on objects too small to render well on film. > > 3. Can someone recommend the finest-grain development regime that >keeps TMX's speed at 100 and its curve as straight as possible? I usually >use hyperdilute Rodinal or 1:1 Xtol, but the former changes the toe and >shoulder, and the latter may be too grainy for testing lenses. I prefer Delta 100, but I agree with you with regard to the developers. Xtol gives me the straightest curve, or shall we calle it "line" because that is what it is. > >Testing Notes: > > 1. I just got finished running identical tests with two bodies >for focus and RF operation, using an M3, a Hexar RF, a 21 Kobalux, a 35 >Summicron, a 50 Hexanon and a 90 Hexanon, using all lenses on both >cameras, shooting from 2.8 to 16 on all of them. RF alignment was >absolutely identical between both. I will report back on whether one >body produces sharper pictures than the other. > > 2. Hexar metering - for the M3 shots, I established an exposure >of f/16 and 1/30 (and equivalents) by using a Zone VI spotmeter on the >street and setting the street to Zone V. When I reshot all of the tests >with the Hexar, AEL produced this same basic exposure with all four >lenses, and did not deviate at all. This was true even with the >non-retrofocus 21. So is this oft-discussed superwide metering problem >just with the M6? Or is there some circumstance in which both cameras >would fail to meter correctly? Is this a problem with the CL/CLE? > >Have a great day! >Dante - -- Christer Almqvist D-20255 Hamburg, Germany and/or F-50590 Regnéville-sur-Mer, France