T2 adapter & inside ~45mm thread

[ricardovaste]

<p>Hello,</p>

<p>I'm using a T2 adapter on a lens I have. The rear element isn't particularly small, but there is still a fair amount of room left around the inside diameter of the T2 adapter and the outside diameter of the rear element/retainer.</p>

<p>The one i have seems to be roughly 45mm. It's threaded too, which makes me wonder what was designed to thread inside the T2 adapters? And is there something i could buy (a small ring) that would thread up inside and give a tigher fit between the rear element and the inside of the adapter?</p>

<p>Thanks for any info!</p>

[JDMvW]

<p>I'm not at all clear what you're talking about. The T2 adapter comes in two parts and the inner ring is fastened down with the small screws in the holes on the side when you have the orientation of the lens where you want it.</p>

<p>It sounds like you may just have the outer ring of a T2 adapter?</p>

<p>I don't understand how you could actually be using the lens that way though?</p>

[Matthew Currie]

<p>I think what you have is not a T2 adapter. There exists a similar adapter using a ~45 mm. thread. I've never come across enough information to determine what, if anything, it was called. I have one in Nikon mount on a Hanimex preset lens. I have never seen another such adapter, nor ever another lens that takes it. I think you may have found another rare example of this bastard adapter. If you are actually looking to mount a T2 lens with a 42 mm thread on to a camera, you should set that one aside and get a proper T2 adapter.</p>

[john_shriver]

<p>Komura Unidapters are about 47.5mm thread. It doesn't use the double-ring with setscrews design of T-2 mounts.<br>

There's also a mount much like a T-2 mount, but with 46mm threads. I have it on a Haminex fisheye, but that doesn't say whose idea it was, since they were just a reseller of imported lenses in Europe.</p>

 

[Matthew Currie]

<p>The one I have resembles a T-2 with inner and outer rings and setscrews. Remeasuring, it comes out as 46 rather than 45 mm., but I'm guessing this is the type in question. I wonder if anyone but Hanimex used it.</p>

[ricardovaste]

<p>The way I understood it is there are lots of variations on the T2 type adapters anyway. Mine is the two part T2 adapter, it is a kood adapter too so it's not an odd sample. I'm not talking about the end that mounts the other ring, I'm talking about the end that mounts onto the camera, the inside of that there is a ~45mm thread. But, anyway, sorry to cause the confusion & thanks for your help :)</p>

[Matthew Currie]

<p>So this is a fully operational adapter, but you're looking at the inside of the camera end and wondering what the internal threads are for? </p>

<p>If so, I think if you look very closely, perhaps with magnification, and try to find a point where the thread starts, you may find that it only looks like threads, but that it's actually axial grooves, rather than helical threads, cut in to act as a light baffle. </p>

[curt_saxton]

<p>The only thing I know of with 44mm thread mount would be a Miranda, some of which had both bayonet outer and M44 inner mounts on the body so lens would be M44. Don't think this is the case with yours though.</p>

[ricardovaste]

<p>Matt, I went to the adapter and picked up a 50mm and inspected it, hoping to find what you thought... damn! I found the start of a thread, and i could actually follow it 'around and down' with a toothpick.</p>

<p>Mystery continues!</p>

[Matthew Currie]

<p>I was motivated to check a few T adapters I have around. Some, especially the cheaper ones, have threads, while others, including the visibly better made Vivitars, are grooved but not threaded. The sizes vary. Several are very close to the same size as the threads at the lens end, with what looks like the same pitch, but they're different enough not to fit. None appear to fit anything. <br>

My conclusion from all this is that because threading is a simpler machining operation than cutting axial grooves, it's how some manufacturers produce light baffles in cheap aluminum parts.</p>