Archived posting to the Leica Users Group, 2002/01/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>A blue box arrived at the house today for my V35 enlarger with >Schneider's 40mm f2.8 APO lens inside. > >I believe Erwin in a LUG posting some time back called this lens >superior to Leica's 40mm F2.8 Focotar lens. No mean feat. > >Now I'm planing to find out for myself and post the results. I plan >to do a series of side by side tests using the same negatives, paper >and chemistry. The enlarger and selected lens apertures will also be >the same for both lenses and each test series will be fully >completed before I turn the enlarger off for the night. > >Suggestions on testing processes from Luggers who have done this >type of testing before would be appreciated. Greg: just a few thoughts: I am sure the Schneider APO is better fully open than the Focotar fully open, but this is not relevant. I think you should do the test at your normal working aperture. Say this _has been_ 5.6 and then it would only be relevant what the difference is at that aperture, UNLESS you always wanted to work at 4.0 but found this was not practicable because your prints did not turn out sharp enough at that aperture. I do not think you will see much difference unless you enlarge at least 12X, better yet 16X. This does not mean that you have to use very large paper ;-) Just enlarge part of the negative. There will probably not be much difference between the two lenses if you look at centre of the picture. You may find it more interesting to check the difference in the corners. I suggest you move your negative so that the centre of the negative is projected in one of the corners, as the negative itself may be less sharp in the corners and that may make it difficult to judge the difference between the enlarger lenses. Or do you have a special test negative? What I think is a very interesting question is whether the APO will focus automatically. I know both lenses are 40mm lenses, but that is just part of the name, or a general classification, and one could well be 39 mm and one 41 mm focal length and that may affect the automatic focusing. Now resolution (or sharpness) is one thing, and micro contrast is another. In my opinion the latter is important too, and it can be tested by enlarging a section of a negativ with average density, say caucasian skin in the shade, or some sort of fabric without much pattern. Here we come into the areas of taste, but it is important. I am very curious to hear what your results will be. Chrtis - -- Christer Almqvist D 20255 Hamburg and / or F 50590 Regnéville sur Mer - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html