"No lens mounted" -- is it the lens or is it me?

[CP93]

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I bought a Summaron 35mm f/3.5 in screw mount.

I have two Fotodiox LTM-to-M adapters.

Both adapters work fine with my Voigtländer 35mm in LTM.

But the Summaron, although it mounts correctly on both adapters, still gives me the "No lens mounted" from the M10-R, and the focus patch moves partway and then stops moving even though the focus ring continues to the end.

Is this a known issue with this comblination? Is the lens defective? Am I?

TIA.

Edited August 5, 2024 by CP93

[TomB_tx]

The Summaron 3.5 ltm is very picky about a correctly machined adapter due to the milling of the base for the cam follower.

Here's a correctly machined adapter that has room for the roller follower to enter and allow range of focus

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Here's an adapter that doesn't have enough clearance for the roller, so it can't follow for close range.

Edited August 6, 2024 by TomB_tx

[CP93]

35 minutes ago, TomB_tx said:

The Summaron 3.5 ltm is very picky about a correctly machined adapter due to the milling of the base for the cam follower.

Here's a correctly machined adapter that has room for the roller follower to enter and allow range of focus

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Here's an adapter that doesn't have enough clearance for the roller, so it can't follow for close range.

Thank you, I think this is the problem.

Back it goes. I'll buy one in an M mount instead.