Bolex SBM - Fitting a Vario Switar 86 Zoom

[Graham Ellard]

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.

 

[Jean-Louis Seguin]

It’s not possible.

Only the bayonet versions work on the SBM.

Many other non-Bolex zooms will work fine.

JL

[Graham Ellard]

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.

 

[Todd Pinder]

That Vario Switar you show has Bolex bayonet mount, c mount to bayonet mount adapter will not work with Vario Switar zooms!

[alexandre favre]

According to Yves Bornand, a Bolex technician, the rear ring of the lens can be resized using a lathe. This procedure, illustrated with the POE zoom, is applicable to the Vario Switar 86 as well.

[Graham Ellard]

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!