View Full Version : Rodenstock Imagonal lens

Thierry Schreiner
26-Dec-2006, 12:21
Hi everybody,

Can enybody tell me what a Rodenstock Imagonal lens is?

Anything to do with the Imagon? When was it made, what focal lenghts did it have and so on.

Thank you in advance and best regards


Jason Greenberg Motamedi
26-Dec-2006, 12:36
The Imagonal was actually several lenses. It was sold primarily as a casket set which came with both landscape (sharp?) and portrait (soft?) elements although I think one could also purchase individual elements.

In design, it has almost nothing to do with the Imagon. The Imagon is an achromat, and--if I remember correctly--the Imagonal was a bizarre design, the front group was three cemented elements, while the rear was a singlet. I can't recall which was interchangeable.

They are fairly scarce; I have only seen one. I am not sure how usable they will be today, as I do not think they were color corrected for pan-film.

Ernest Purdum
27-Dec-2006, 10:03
Kingslake lists the Imagonal the other way around, singlet front, triplet rear. The German patent of 1904 was number 177,266. I have heard that obtaining German patent copies is rather easy, but haven't tried it.

Jason Greenberg Motamedi
27-Dec-2006, 11:06

You may be correct, I was just running from memory. The Vademecum lists it the other way (triplet front, singlet rear) but I would be more inclined to believe Kingslake.

Ole Tjugen
27-Dec-2006, 13:16
Singlet front, triplet rear makes sense for a replaceable-front casket set. Then all the corrections could be put in the "fixed" rear cell, which would need to be a triplet to work adequately across a range of focal lengths in the front.

For a non-convertible lens the other way around makes more sense; putting the greatest focussing power behind the aperture makes the corrections easier.

So maybe both statements are correct?