First of all: I am geman and rodenstock is a german company.If I want to know something I just call them. Its a very nice company, they are very helpfull.
second : I talk about the 55 mm when a get one with technical guys from rodenstock, they explain me what the difference is.
So read what Rodenstock write about the difference exactly, and what they mean by that.
The physical design is the same. The calibration different.
The image circle are same: the differance is to write about the right aperture-image cirlcle for digital and for analoge. The first 8-11 for digital, second 22 for 4x5 analoge.
The image circle grows to 22 and is 110° at both.
I will not repead myself any longer.
To allan:
sorry that I must say it: you are wrong.
Apo sironar digitals are not Apo sironars!- absolutly not!.
This name is indeen not really helpfull, therfore the new name Digaron is really better.
the digitals have nothing to do with Apo sironars- rodenstock choose the totaly wrong name for it.
Apo sironar N lenses are 6 elements 72° lenses like Symmar- not Planars!
this are standart and longer lenses for 4x5-8x10...
only some longer Apo sironar digitals (maybe only this one) like 105 mm are old apo sironar N 72°, so 6 elements design.
The wider apo sironar digital are apo grandagons 35,45,55, 8 element wide angle constractions ( like super angulon) 120° and 110° designs, very well corrected, developed for 120 film. only 55 cover 4x5.
When you compare pics than compare the right pics: compare 55 grandagon and 55 digital, and you will see the same design. The longer A.sironar digital are different, mixed constructions from sironar and rodagon ( same apo componon by schneider),
Some lenses are made new: for examle 90 mm digital, but based on film lenses. Of course the HR are fully new thing and fully digital.
I thing I wrote enough till now. I will not write any more to this case.
Lorenzo just make your experiance- it will be fine.