scratchy lens mount feel

[Ashishmunde]

I have a 77D and all the lenses I have had for it so far (18-55 STM, 55-250 STM, and 50mm f/1.8 II) all have the polycarbonate mounts. I got a 24mm STM and 50mm STM, which both have metal mounts, and when I put them on my camera, they have a slightly scratchy feeling when twisting them on; the poly ones are totally smooth. Is this normal? Do metal mount lenses just have a scratchy feel to them when you put them on; or is this something that goes away over time; or do I have a bad mounting point on either the lenses and/or camera body?

[kvbarkley]

I have never had a plastic mount, so I can't compare, but there does seem to be some roughness on the metal mounts.

[ebiggs1]

"Do metal mount lenses just have a scratchy feel to them when you put them on;"

No they don't.  I have had several dozens of lenses from various manufacturers and none have a "scratchy" feel.

[wq9nsc]

I haven't noticed a scratchy feel on any of my EF mount bodies and I still have the EOS 650 film body I bought a LONG time ago.  But I haven't used a plastic mount lens either and I wonder if you have some residue from those plastic mount interfaces built up on the camera body? Some varieties of plastic are designed to be self lubricating so it is possible they are leaving something behind on the camera body side. I would take a close look at the mounting flange under a good magnifying glass and also take a close look at any of the lenses themselves that have the issue.

I spent some time this morning checking the AF behavior of a new to me EF 300 F2.8 by itself and with a 1.4X so the combo was on and off of my 1DX 2 several times and even with this very heavy lens I didn't notice anything but the normal smooth feel.

Rodger

[kvbarkley]

"Scratchy" is way too dramatic for what I feel. The serface is machined with about 1 mil grooves - you can feel it with your fingernail - and with some lenses those grooves rub against each other as you mate the lens.