Rodenstock Apo and non-apo Rodagon enlarging lenses

[jose angel]

After reading the Ctein´s book and looking at the Rodenstock literature (Paul Butzi´s scans -I know that this data charts given by manufactures are theoretical-), I arrived to the conclusion that either the apo and non apo enlarging lenses have moreles the same performance at working aperture and magnification, even better for one of them to its apo counterpart (105mm lenses, MTF chart). Also, in terms of light fall-off and distortion, the non-apo versions surpass their apo equivalents.

Is it correct?

I would like to know about the color aberration differences and corrections in this apo and non-apo versions. I wonder if the benefit of this lenses resides only on this topic, and in what manner this benefit really affect (or theoretically could affect) to the prints. Could this difference be obvious only for color prints? I understand that most of us use color filters for b/w work with VC papers. Also, I have read a lot of times that the apo lenses only could be checked in the corners of very high prints... the MTF charts don´t reflect it in all cases. I´m very curious about it.

Could anybody give a more detailed explanation about this topic? We would be highly thankful...

[David A. Goldfarb]

I have 50/2.8 and a 90/4.0 Apo-Rodagon and they do seem sharper than other lenses I've used, including various EL-Nikkors, Componon-S, and Rodagons. I have not compared them to Apo-Componon or Apo EL-Nikkors. It may just be a matter of better coatings producing better contrast, but given the price that enlarging lenses command these days on the used market, it seems worth it to me.

[John D Gerndt]

I cannot add to your understanding of theory. I can chime in that build quality might be a bigger variable than design. I have used APO and non-APO versions and can see a difference, just barely at 4x enlargements in both color and black and white. I did my test blind to the notes on the back that told me which was which. I was surprised to find though how close some other lenses tested to that very expensive APO lens. For anyone on a tight budget I would say there are better places to spend money in the chain of equipment that produces a print.

[robert lyons]

some time ago i did a test of my 15-20 year old el nikkor 105mm against the apo-rodagon. the images were 20"x30" prints from 6x9cm 400 speed color negative film. i was surprised to find that at this magnification there was "little" difference in sharpness if any. there was to my eye a difference in color balance and i think this is attributed to the difference in german and japanese lens coatings. the german lens was a bit cooler and overall i preferred the el nikkor. i agree that there are other places to spend $$$ as i do not think you will really see much difference unless you are doing ultra large prints.

[Bob Salomon]

" test of my 15-20 year old el nikkor 105mm against the apo-rodagon"

Against which Apo Rodagon? The 105mm Apo Rodagon-N?

Under what conditions?

Properly aligned enlarger? Glass carrier? At what aperture?

[jose angel]

Thank you for your reply. I understand that all this literature from quality or specs of lenses are... "ilustrative". Why are the apo versions twice the price of their no-apo counterparts? I would like to have this lenses side by side for testing... it´s the only way to know what we are really buying (and reading).