Olympus OM 100/2.8 a Sonnar?

kanzlr

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Hi,

I just examined the lens diagram of Olympus 100/2.8 lens and wonder if this can be considered a Sonnar type, as it looks close to me:

E_100_2.8_Schnitt.jpg


Source:
http://olypedia.de/Bild:E_100_2.8_Schnitt.jpg
 
The Olympus Patent for this lens calls it a 'variant Ernostar'. The Patent describes an Ernostar with an extra element in the front group. The Ernostar evolved into the Sonnar (both being designed by Bertele). I think the Olympus 85mm f2 is more like a Sonnar. It's the same construction as the CONTAX T2 Sonnar, for example, and bears a passing resemblance to the current Zeiss Leica-mount Sonnar. The 85mm f2 is an interesting lens because Olympus seem to have tried to address the focus shift problem by allowing relative movement the front and back elements at close focus. I wrote about this on Photo.net some years ago. Google 'Olympus OM 85mm f2: the OM Sonnar' and the thread should come up.
 
Well, it is hard to tell without a glass list, but by looks it could be considered derived from early Ernostars - from which other development strands led to the Sonnar. But the latter emphasized very, very different aspects.
 
Anyway, FWIW, I have both the 100/2.8 and 85/2 - the famous floating element in the 85/2 might exist, but in practice it is a myth, because that lens focus shifts markedly, and with standard OM screen, it actually delivers sharp images only from f2.8 on. This might be why Jane Bown was famous for shooting her Olympus Sonnar at f 2.8. For me both lenses perform well, but the 100/2.8 is more reliable in use.
 
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