Spectra Duo-Focus Telephoto lens 140mm F:4.5 W/converter. lens 230mm F 7.9 Extacta?

[Kino]

Found this lens today in an antique store and it intrigued me. I have found scant little information online about the actual use and means of conversion with the included "tele converter" barrel.

Does anyone have any first hand knowledge of this lens?

It appeared to be Exacta mount, but it will not fit either a VX 1000 or an Exa 35mm. The mount has two bayonet rings which might give a clue as to which mount it actually could be.

Maybe the mount has been wrecked, a piece of the lens is missing or this is another mount entirely; I do not know.

I have only found a sample advertisement for this lens online, but it does nothing to clear up any operational confusion.

1958 Exakta Camera, Spectra Duo-focus 140/230mm Lens Ad-P193

www.vintagepaperads.com

I cannot figure out how the tele converter adapter mounts on the lens unless you disassemble the lens barrel and those tiny, tiny set screws.

A PDF of the lens instructions would be great if anyone possibly has the original instructions.

Thanks for looking.

 

[Kino]

Well, well at least I have discovered it was made by the precursor to Tamron; Taika and had the precursor to the Adaptall mount.

Pretty sure now this is NOT an Exacta mount...

 

[reddesert]

That looks like an early T-mount lens to me. The mount adapter should screw off, but maybe it's on there really tight. Then you would screw-mount the tele converter between the lens and the mount adapter.

The tiny set screws in the mount adapter should not need to be unscrewed all the way. They bear on an inner ring of the mount adapter. You can loosen those setscrews a little to rotate the lens with respect to the mount adapter/camera, then tighten them again once the desired rotation is set. Current T-mount adapters usually work this way as well. Apologies if you are intimately familiar with T-mounts and knew this already.

 

[Kino]

That looks like an early T-mount lens to me. The mount adapter should screw off, but maybe it's on there really tight. Then you would screw-mount the tele converter between the lens and the mount adapter.

The tiny set screws in the mount adapter should not need to be unscrewed all the way. They bear on an inner ring of the mount adapter. You can loosen those setscrews a little to rotate the lens with respect to the mount adapter/camera, then tighten them again once the desired rotation is set. Current T-mount adapters usually work this way as well. Apologies if you are intimately familiar with T-mounts and knew this already.

Ah, always ready to learn something new! I will give it a go...

 

[Kino]

OK, got if figured out; at least how the tele converter works and the mount.

For some reason, the T-mount ring would not screw off the back of the lens, even with great pressure. However, once it loosened the grub screws that held the mount in place, the mount slid off and the ring then unscrewed with minimal fuss. Maybe the grub screws were distorting the shape of the mounting ring?

Once that came off, I was able to get access to the very top of the helicoid to drop a few drops of alcohol down inside the meshing interface to free-up the focus tube. After working it for a while, I cleaned off the old oxidized grease that emerged, put some new helicoid grease on the grooves and worked it down into the full length of the helicoid. It now will focus smoothly throughout the range.

After that, it was a no-brainer to simply screw the tele converter into the rear of the lens and the lens mount to the rear of the tele converter.

The lens is in great shape; I think it was hardly every used and the advertisements of the time indicate it was an inexpensive lens, so it probably wasn't actually used that much.

Still have no idea what mount I have on this lens, but I thing I should be able to find a T mount adapter for this thing if I look around. The lens barrel thread for the adapter is small; only 37mm in diameter.

Edit: "the mini T-mount used a M37×0.75 thread"; this is not a T2 mount.

T-mount - Wikipedia

en.wikipedia.org

Thanks for the help, @reddesert !

 

[dynachrome]

Somewhere I have a lens which is marked Duo Tamron. It may be a later version of this lens and is in T mount.

 

[Kino]

Somewhere I have a lens which is marked Duo Tamron. It may be a later version of this lens and is in T mount.

Probably so; Taika (later Tamron) made several versions of this lens and it was marketed under a lot of different house brands.