Rodenstock UV Rodagon 80 mm f/5.6

[enricosavazzi]

Some time ago I was contacted by a person who found this lens among his late father's possessions and sent me the attached pictures. I do not own this lens, so I cannot contribute any first-hand information. Information on this lens is notably absent, for example its is not mentioned in Klaus' database at http://www.macrolenses.de/objektive_sl.php?lang (although a copy of a Rodenstock data sheet that includes the UV Rodagon 80 mm is indeed published on his site). This lens is mounted in a re-purposed barrel originally designed for enlarger lenses of the same age, like all other UV Rodagons I have seen.

 

The lens barrel has been custom-modified with the addition of a vent, probably used to allow air passage to the outside of the barrel for using the lens in a vacuum, or alternatively to replace air in the barrel with a controlled atmosphere, for example nitrogen to avoid ozone formation during exposure to low-wavelength UV radiation. This modification also blocks the aperture ring at f/5.6.

 

If the specifications of this lens are similar to those of the other UV Rodagons of the same age and mounted in barrels of the same style, this lens is designed primarily for use in UVA around 365 nm, and is still quite usable at 310-320 nm (with roughly 50% of its peak transmission, which is at 400 nm). It is not designed for ozone-forming UV wavelengths, although of course you might be able to push some medium-UVB through this lens with a strong enough source.

 

The spots around the periphery of the front elements are a typical example of "Schneideritis", caused by black paint lifting off the painted girdle of the optical element. The rusted screw head is a possible indication of use in a corrosive atmosphere, although excessive humidity and/or a defective chrome plating may also result in this type of rusting.

 

I have a page on the UV Rodagon 60 mm f/5.6, which is externally very similar, on my web site at http://savazzi.net/photography/uvrodagon.htm. Other known focal lengths for UV Rodagons are 105 and 150 mm, so at least four different focal lengths were made.

 

 

 

 

 

 

 

 

[colinbm]

Wow, how very different.

[Andy Perrin]

Is it a glass lens?

[enricosavazzi]

It is made with some kinds of optical glass, but I don't know which types. I never saw quartz or calcium fluoride mentioned in connection with UV Rodagons, so probably neither is used. The optical scheme is 6-element 4-group comparable with double-gauss, but the two cemented doublets are outermost (not innermost like in the "typical" double-gauss).

[Andrea B.]

Amazing that there are some UV lenses "out there" which are still not well known. Thank you for these photos of the UV-Rodagon 80/5.6.

 

I note that the 80 has that same pesky aperture window as the 60 which I have (like you). Klaus once said to paint it over with black nail polish, but I never had the nerve to do that to such an expensive little lens even though it would have been a very useful modification.

 

It is made with some kinds of optical glass, but I don't know which types. I never saw quartz or calcium fluoride mentioned in connection with UV Rodagons, so probably neither is used.

 

Marco Cavina mentions that the UV-Rodagon 60/5.6 is realizzato con vetri speciali (made with special glass). That seems to imply one of the usual UV-passing glass types for UV-Rodagons?

 

 

 

[enricosavazzi]

Yes, they are barrels designed for enlarger lenses used in darkrooms, so they have the usual illumination for the aperture scale. I have not noticed any VIS/NIR contamination through these windows, but it is possible to reversibly cover them with a black tape (e.g. there is a black-paper masking tape sometimes found in photography shops) or with a patch of the adhesive foil used to cut internal reflections in extension tubes (Protostar and similar, you can search for e.g. "flocking material").