Archived posting to the Leica Users Group, 2002/01/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Christer, I plan to test at all apertures with the Leica B&W test negatives, but concentrate on f5.6 through f11 with print comparisons of a range of negatives from extra thin to thick and in-between. I had not thought of moving the negatives position off centre to test the corners and your suggestion here is a good one that I will also include in my test process. I only had a couple of hours last night to get everything set-up, but I hope to spend several hours Sunday afternon printing, comparing and printing some more. One real apparent difference last night is the Schneider lens is noticeably faster than my 5 year old Focotar. Regards, Greg Christer Almqvist wrote: >> 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 - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html