The experience here seems to point to a real difference. The
APO Rodagons seem to be the best of the bunch, although they
really are not apochromatic according to their published data.
They have extremely good color correction but apochromatism has a
very specific definition and the lenses don't meet it. Probably
of no practical consequence.
The illumination of a lens of normal construction varies with
the angle of view. So, using a longer lens for enlarging will
improve the center to corner uniformity of illumination. This
generally gets a little better as the lens is stopped down
because when wide open the edge of the mount obstructs the light
path. About two stops down from wide open overcomes this but you
can see it. Some lenses have extra large end elements to
eliminate this effect.
Because of the height limit of my enlarger I use a slightly
shorter lens for 4x5 but use a dodger to burn in the corners when
printing from a full negative.
Contrast is critical for color work but less so for B&W
because overall contrast can be compensated to some degree.
However, what is called edge contrast remains important because
it affects what is interpreted by the eye as sharpness.
Rodenstock specifies the optimum magnification ratio of their
lenses. Any lens can be optimized in design for a specific ratio.
It's corrections will not be as good at other ratios. I have not
looked at a Rodenstock catalog recently but they used to offer
different versions of some lenses for different optimum
magnifications. This is one of the reasons that camera lenses are
often not very satisfactory as enlarging lenses.
Lenses like the Rodagon also work very well on cameras for
macro work.
On 11/26/2019 10:22 AM, Luis Miguel Castañeda wrote:
`Richard Knoppow writes:
I doubt if there is enough difference between Rodenstock and Schneider to be concerned about.
I do prefer the rodagons over the componons, by a huge leap. But... it's a matter of my own preferences. Can't complain about componon performance or even nikkor, but I like my prints better when done with rodenstock glass.
Specially the Apo-Rodagon 80. I have a few others from 50 to 300mm, but that one is the one that pleases me more. Ah, and an old meogon (meopta lens) which always delivered, but it's a bit dark.
