I recently decided to upgrade the quality of my older Leica Focotar f4.5 enlarger lense with a Leica Focotar-2 lense for use on my Focomat 1C enlarger. This enlarger has a condenser light head. Since the Focotar-2 lense is also an older design, and has not been available new for some time, I thought that maybe some of the newer lenses with more modern designs could possibly provide better performance. I appraised several 50mm enlarging lenses. These included an older Nikor f2.8, a Leica Focotar-2 f4.5, a new Nikor f2.8, and a new Schneider Componon f2.8. In terms of resolution, the Focotar-2, the old and new Nikons, and the Schneider lenses tested very well, with the Focotar-2 just edging the others, especially at the smaller apertures. The old Focotar was very close, but lost out at f11 and 16 to the others. But what really surprised me was the color fringng and ghosting flare that I observed with the new Nikor and Schneider lenses! The older Leica and Nikor lenses showed very little color fringing and flare, and this was only at the first one or two apertures. In looking for an explanation, I noticed that the newer lenses have large rear elements compared with the older lenses. The difference between the two Nikors was especially apparent. How could they both be f2.8 lenses when the rear element of the older Nikor was only half the size of the new Nikor? My conclusion was that the older lenses were designed for condenser enlargers, where the light is focussed and concentrated onto the rear lens element, whereas the newer lenses are designed for diffusion enlargers where to be a true f2.8 lense they require large rear elements. I did not test these lenses on a diffusion enlarger, but suspect that the color fringing and flare would not be a problem with this light source. My conclusion is that the newer designs will not perform well on condenser enlargers. Have any of you experienced problems like this with the use of modern lenses on condenser enlargers?

-- Eilert Anders (eilert@dav.com), November 07, 1997