betax with focussing mount - whatizzit?

[Nathan Smith]

I received this shutter along with another item in a recent auction. I'm guardedly excited about it: it looks very useful, but I'm not certain how.

It's a Betax #4 on a focussing tube mount. Since it doesn't have an aperture I assume it's for use with barrel lenses, though I haven't yet gotten around to trying any out in it to see what fits.

It would seem that the tube would cause vignetting with many or most lenses, is this for a particular use? So, there's one question, the next is: what was it's intended use? and another, what lenses might fit such a shutter?

Thanks for any and all info,
Nathan

 

[MikeK]

Are there any lens elements inside the tube? Looks like a front mounted shutter to me. Front mounting a shutter is a way of using a barrel lens without having to use the lens cap or a hat as a shuuter. The tube abd focussing knob suggests it came of a lanten slide projector.

Mike

 

[Nathan Smith]

Nope, it's not a lens, just a tube. It is indeed very much like a projector setup, but why would you need a shutter for that? These are questions I've been asking myself, too ... hmmm.

As I said, since it doesn't have an aperture I'm pretty sure you're expected to put a barrel lens into it, though not certain. The photo shows it in it's most retracted state, the focussing tube will extend another couple of inches.

Nathan

 

[darinwc]

It looks like an extention to use long lenses, with a shutter. It would be very useful for some of those old long barrel lenses.

 

[Uncle Jim]

Nathan,
Could it possibly be for use with microscope? It wouldn't have any lenses in it then ,as they would be part of the microscope. Another use could have been for use with an osiloscope.
uncle jim

 

[Nathan Smith]

Jim - I kinda sorta thought about that too ... maybe, but considering the bulk of it, I don't know. Also, 2" extension is a bit much for microscopes ... and they'd do the focusing anyway I think. The oscilloscope, maybe ...

Darin - that's what I'm thinking, but doesn't it seem like that would cause some serious vignetting? Maybe not. Or maybe not if you're doing a smaller format like 6x6?

As I said, I'm guardedly excited about this ... I'm really hoping I'm wrong about the vignetting and it would allow me to use some longer lenses on my 5x7 2D than I'm otherwise able to take advantage of.

Calling Jim Galli! Jim's gotta know the answer to this one ...

Nathan

 

[phfitz]

nathan,

I think it was used like this one for macro work:

ebay Tessar Macro

Raptar 300/6.3, Velostigmat series IV 300/6.3 and the Velostigmat series I triple convertible all fit a #4 shutter.

Have fun with it.

 

[Nathan Smith]

That makes perfect sense, thanks for the info!

 

[jimgalli]

Calling Jim Galli! Jim's gotta know the answer to this one ...

Nathan

Nope. I've seen the 4 Betax's once in a while with no aperture but never knew what the original intent was. Paul's probably onto it.