I sent the following to the list in December 2000. Things may have changed in the quality of enlarger lenses since then, but I believe what has not changed is that self testing is by far the best way of selecting a lens. I hope this dig into the past is still helpful to the present discussion.
Quote.Catching up after a week away from the list, I found the comments on enlarging lenses interesting. Graham is right, a grain magnifier is no substitute for carrying out some simple practical tests. With the help of my friends who kindly augmented my collection of 35mm enlarging lenses, I set about testing a number of optics that included Dallmeyer, Leitz, Meopta, Minolta, Nikon, Schneider and Zenith (the one supplied with the portable enlarger).
My test negative was a piece of microfiche of very fine print held in a glass carrier diagonally across the frame. Alongside this in the other half of the frame was placed a piece of grain screen. With the enlarger set for 12" x 16" prints the results were revealing. All were tested at full aperture and down to f8, with the test strip laid from the centre to the corner of the easel. Predictably the results at full aperture varied, but the "best" names did not always give the best result. Then on stopping down things began to even out, and at f8 there was really nothing between them in terms of sharpness. So it seems that f8 is a great leveler! It is pointless me giving you my results because lens performance will vary within a given make and specification. Suffice to say, for the Meopta enthusiasts who have commented on the list, my particular Meopta lens performed extremely well. And the worst performance was put up by a most illustrious name!
The second test, was for contrast, and I used a method that I think was first described by George Wakefield in the AP some years ago. A small plated washer was placed on the glass carrier, and its image focused to the same degree of enlargement as before. A test strip on grade 2 was made to determine the D-max. The printing paper was then placed on the easel and a cheese shaped segment is covered by the corner of a black card. The D-max exposure was given and the print developed normally. A high contrast flair-free lens should show a pure white image similar to that of the white segment covered by the black card. This was not the case with most of the lenses tested; the flair producing varying amounts of light grey fringing within the image of the washer. This is a pretty demanding test,and of course a slight lack of contrast can be corrected by adjusting paper grades. Interestingly the worst performer in this test (an old Dallmeyer) was amongst the sharpest in the previous test.
Hope you find this relevant; it certainly supports what others have said about testing before buying. It also supports using your own experience rather than that of someone who has been fortunate in buying a good sample:-)
Clifford. Somerset U.K. ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.
