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CS (contax screw) adapters
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PostPosted: Sun Apr 30, 2017 12:09 pm    Post subject: CS (contax screw) adapters Reply with quote

An interesting old thread here relating to CS adapters:

https://www.photo.net/discuss/threads/spiratone-cs-mounts-and-t-mounts.334396/

Where adapters are concerned, there are no dull moments.


PostPosted: Sun Apr 30, 2017 11:19 pm    Post subject: Reply with quote

I've just spent ages measuring T2 mounts, CS and CY mounts, and you're right - there are no dull moments.

I picked up a strange 25 / 3.5 preset lens, branded 'INA' , which does not seem to reach infinity - it's nearly there. And the focus ring was all over the place, so I set about adjusting that to where it should be hoping that the stop was preventing it reaching infinity. But it's not, so I embarked on dragging out all my T mount lenses and measuring them accurately. There is some variation between mounts.

I have five T2 mounts, thinnest 9.46mm thickest 9.6mm. Average = 9.526. Difference = 0.14mm

I have two CS mounts, 9.61mm and 9.58mm. Difference = 0.03mm

And one CY mount that is 9.61mm

The CY will only fit one lens, a Hanimex ( Tokina ) 180 / 3.5 with a 47mm thread on the lens instead of the 42 x 0.75 thread for T mounts. But the CY was probably a variation of T so the thickness might be the same? 9.6mm is the same as the thickest T mount I've got.

The problem I have, and it's not easy to resolve, is I now think that the T2 and CS mounts have got mixed up from their original lenses in a few cases Rolling Eyes And some lenses seem to be ok with a slightly different mount thickness, but some aren't. The INA came without a mount so I just screwed one off a Soligor 400, the thickest one, I need to try the thinnest one and see if it reaches a sharp infinity. But of course, a 50 year old preset wide angle might not have been sharp from day one.

The CS mount was ( I think ) Miranda's baby, the two I have are chromed and marked CS. One was definitely on a Yashinon 135 preset and the other on a Tamron Twin Tele preset - but the other Twin Tele I've got came with a T2. And both CS mounts are two part mounts the same as T2

The 0.14mm variation is not a lot, it's 5.5 thou' for those of us that like inches. Slightly more than the thickness of ordinary printing paper - would that be enough to alter a lenses ability to reach infinity if the lens focus ring is up against the stop?
I need to try a good lens on a tripod, set it to infinity, wide aperture, tape the focus ring down, and then change the mounts.