Graham Ellard

We've been given a Vario Switar 86mm Zoom. Cosmetically it doesn't look great, and the aperture and focus were very stiff. Having dismantled it, cleaned it and begun to reassemble it I'm really puzzled by one of the parts. I haven't been able to find any references or images online that tell me what it is or what its function is. It looks as if it has been machined and modified in some way, like a customisation. Plus, having very carefully reassembled the iris assembly and don't understand how the aperture ring engages with with the iris assembly. The ring runs smoothly but is not connected to the iris assembly 'tube' in anyway, and I can't see how it can be. Maybe there was a missing part originally, maybe the mystery part has something to do with it. I'm baffled, and would wlecome any thoughts, suggestions, or advice. Here are some pictures that show the part in place, separately and the iris assembly in place, with and without the mystery part. Thanks!

Thanks Aelxandre, Todd, That's very helpful. So there are SBM specific zoom lenses with bayonet mounts. The idea of machining the ring on the lens sounds daunting, but perhaps... Thanks again!

Thanks for your response JL. We've seen numerous images of an SBM with a this same zoom lens fitted, so this is confusing. We have the c-mount to bayonet adaptor which allows us to use our other c-mount lenses on the SBM. It's this adaptor that doesn't work for the Zoom.

Hi, we recently acquired a Bolex SBM, to use along side our Bolex RX5. We have a c-mount adaptor and can use all our existing lenses with the SBM - except the Zooms (we have the Vario Switar 86 standard and the 86 OE). The c-mount adaptor is fine for all our primes, but the diameter of its concave depression is too small to allow the Zoom lens thread to reach and engage with the adaptor thread. Clearly there must be a way to fit these lenses to an SBM, but we can't find any references to another type of adaptor. We have seen references to one with a type of cover plate over the bayonet 'notches' for security when using heavier lens, but that doesn't address the more fundamental issue we're facing. We'd welcome any advice - the spec of the adaptor we need (and likely sources), whether there any other work around, or anything helpful really! We need to use both cameras for a project soon, each fitted with a zoom lens, and need a solution fast. Thanks.