Technical Difference Between T and T2 mounts

visualopsins · Expire: 2025-04-11

Thanks to MFl member Big Dawg now I understand the difference! Very Happy

wikipedia - T-mount

True T-mount lenses have permanently attached inner ring; the outer ring with camera mount attaches to lens via 3 grub screws.

T2 mount lenses have M42x0.75mm threads that accept any T/T2 mount with threaded inner ring.

The difference is, with T-mount, the inner ring is permanently attached to the lens. A T-mount without an inner threaded ring is the original T-mount. T2 mount always has inner threaded ring.

Manufacturers caused confusion, by incorrectly naming some T2 mount threaded lenses "T-mount". (Tentative) any T2 mount (should/)will fit on true T-mount lens by first removing the inner ring.

luisalegria · Expire: 2018-01-18

I must have 50 of these things, and I have never seen a T-mount where the inner ring was fixed. They are all of the same design, with an inner ring that can be loosened with setscrews.

Even the ancestor of the T-mount, Tamrons interchangable mount for its 135/4.5 Converto/Twin Tele had the same design.

I think Wikipedia is not correct.

visualopsins · Expire: 2025-04-11

luisalegria · Expire: 2018-01-18

Interesting point.

The problem here, similarly, is that I haven't seen such an arrangement of a fixed inner ring that is meant to go with a generic or standardized adapter.

There were many such mounting systems from different makers of preset lenses whereby one could just screw on the proper mount as required for the order, sometimes even using the three-screw attachment on a grooved ring on the lens body. Steinheil and Piesker had these for some of theirs. Some of the 1950's Soligor/De Jur types, maker uncertain, also had something like this. I can take a mount from a Steinheil Culminar 135 and put it on a Steinheil Tele-Quinon 200. I even have a fixed-mount 1960's Tamron like this. But this sort of thing was never standard that I know of, these mounts don't work from brand to brand, or normally not even from model to model of the same brand.

More, the inner ring diameter on T-mounts was never standard either, even from the same manufacturer. So an early 60's original Tamron Exakta T-mount can't have an inner ring transplant with an original early-60's Tamron M42 T-mount. You generally can't swap these.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

I think Luis has summed it up well. My suspicion was that the original T-mount was quickly abandoned in favor of the more universal and easier to use T-2 mount, and that the original just as quickly tumbled into obscurity. And that perhaps also just as quickly the T-2 mount's designation was shortened to T-mount just for the sake of simplification.

Big Dawg · Joined: 28 Jan 2009 Posts: 2530 Location: Thach Alabama