Expert opinions needed. Biogon or Jupiter-12?

[newst]

I am just a confused amateur who has read a lot about fake Zeiss lenses. One of the rules of thumb I have been carrying around is that a Contax Rangefinder lens is less likely to be a fake as there is less demand for them. Then today I came upon this...

http://www.ebay.com/itm/Carl-Zeiss-Jena-35mm-F-2-8-Biogon-Contax-Rangefinder-Red-T-exc-A7-full-frame-/331849416787?hash=item4d43c44053:g:ReAAAOSw3mpXLF3G

Now another rule of thumb I have been following is that a red T coatings label was the Zeiss Opton label where Jena used the 1Q and pre-war doesn't matter as for all practical purposes there weren't any commercial coated lenses pre-war, or if there were the chances of my coming across one of those rare lenses are too small to consider.

So, what do the experts think, real or fake?

[BurstMox]

To my eyes, it doesn't look like a Jupiter-12.
You can check all versions of Jupiter-12 here : http://www.sovietcams.com/index.php?1072558845

[alex_KS]

First of all - if you found Zeiss Jena lenses with red T it doesn't mean it's a fake!
According to the serial# that Biogon lens was made in 1940 year, when Zeiss was based in Jena and there was no any Oberkochen factory.
AFAIR Zeiss Jena start to make single coating on their lenses in the middle 1935, so there is nothing weird with red T marking. You can also find It on the Zeiss Jena lenses till the end of 1949 year (+/- few years, I'm not sure).

As for that interesting Zeiss Jena Biogon lens - In my opinion It's original Biogon and not a fake. The main proof is that last digits of the serial # is duplicated on the bottom of the lens block (it's distinctly could be seen on the 7th photo of ebay's link you provide).

And the last question - Is it worth to spend 800$ for It? It depends what you want. According to the fact it's original, it's very rare and hard to find in such condition - I'd say yes, It Is. Is It much better than Jupiter-12 lens? I'm not sure. Maybe it is a bit sharper, but it's hard to say untill you test it.

Would I spent 800$ for It? If you are the collector - why not? Such lenses will bewill go up in price in the future.
If not, I'd rather reccomend to search for KMZ Jupiter-12 lens (Contax or M39 mount), 1950-1959 prod. years for 70-100$.

[newst]

[iangreenhalgh1]

I own both Biogon and J-12. There is little difference, in fact, you will probably find that the only difference you can discern is the performance wide open at f2.8 - the Biogon will be sharp and the J-12 will be a little less sharp. Closed one stop to f4 however, the J-12 will be plenty sharp enough and retains the classical and to my eyes, beautiful rendering.

[stevemark]

[newst]