External-mount lens question

[ssmc]

Okay, so I took advantage of the generous Cameraquest Christmas offer and finally bought a CV SC Skopar 35/2.5. Impressive workmanship, and I finally got to see exactly how external-S-mount focusing works.

My question is this - on both the S3 2000 and an Amedeo S-LTM adapter, there is a tiny bit of play in the focusing i.e. you can turn the lens a little bit either way before the anything happens. The external bayonet is a very snug fit on both the camera and the adapter. Am I correct in assuming that because of the way the spring-loaded sleeve inside the lens has to engage with the inner helicoid that this play is normal, if not unavoidable? It seems to me that the only lens that would be totally "tight" on the S-mount would be an internal-mount 50mm because it's locked to the inner bayonet.

Any comments/suggestions would be welcome!

TIA,
Scott

 

[VinceC]

that sounds right. If you set the camera on B and look at the back of the lens mount with the shutter open, you'll see that even with the external play, there is very little if any play in the silver rim of the lens mount that engages the small wheel of the RF mechanism, so the focus remains very accurate, even for fast telephotos. For external lenses, a lot of the apparent play seems to be related to how the lens is engaging with the gears connected to the focus wheel near the shutter button.

 

[ray*j*gun]

I have 3 external mount lenses that I use on my S3 and they all act as you have described. No issue with performance that I could see.

 

[jonmanjiro]

Some external mount Nikkors I've owned are "tight", but a bit of play is not uncommon with external mount lenses. Nothing to worry about.

Also, the lens may fit on your Amedeo adapter, but the lens plus Amedeo adapter combo most likely won't fit on your M-mount camera due to the rear of the lens coming into contact with the camera's focus cam.

 

[thompsonks]

This Skopar appears on the list of lenses that won't mount via Amedeo adapter? Are you using the regular adapter or the WA one?


"Voigtlander SC Skopar 28mm f3.5 (NO - rear element too large, interferes with rangefinder mechanism)":

How did you get it to mount?

Kirk

 

[jonmanjiro]

How did you get it to mount?

Kirk

You have to machine some of the rear metal shroud off, like Shintaro did to his set of Voigtlander S/C lenses as shown in this photo:


Down size. by edozakura, on Flickr

 

[maddoc]

I think that Amedeo-adapter on the 28/3.5 looks familiar ... 😉 Good idea to machine the shroud off but wonder why they didn`t consider this at the CV factory in the first place ...

The J12 in Kiev mount is a really tight fit on either the S2 and Amedeo adapter, much different the original S-mount lenses.

 

[ssmc]

Thanks for all the replies!

I was aware of the issue with the RF cam and this particular lens so for a quick test I mounted it on a mFT camera via 3 adapters (Amedeo - CV - Metabones). I primarily bought the Amedeo adapter so I could use the 50mm 1.4 Nikkor that came with the S3 on either my IIIf or a future M-body (I should never, never have sold that M6 TTL!)

I had no idea there was enough "meat" in the metal shroud to allow for machining - thanks for that pic! I wonder how difficult/expensive it would be to have this job done?

I was mostly concerned that the slight play in focusing might not be normal but thanks to all this info I feel better about it now! (though I have to admit it's slightly distracting)

Regards,
Scott