Nikon/Contax RF external bayonet tightness

[keytarjunkie]

I recently got an external mount lens (Voigtlander SC Skopar) and the lens is sitting a little loose when attached to a camera. There is too much space between the release tab and the “stop” piece that sits on the other side of the inside of the bayonet.

The problem here seems to be the lens, as the camera works fine with other external mount lenses.

It’s not a huge amount, less than 1 degree, but it’s just enough to bother me. Has anyone adjusted the tightness of an external bayonet mount lens? I couldn’t find any help with this.

 

[das]

I have a similar issue with a Nikkor 50mm 1.4 on an S3. Someone told me that it is not a big deal and will not affect anything. Sometimes the tab on the lens is just a little too small, unfortunately.

 

[Highway 61]

I have a similar issue with a Nikkor 50mm 1.4 on an S3. Someone told me that it is not a big deal and will not affect anything. Sometimes the tab on the lens is just a little too small, unfortunately.

You are talking about looseness with an internal mount 50mm lens, a common issue adressed long ago by the Kiev Survival Site here.

So, your post is off-topic, the OP is about looseness with an external mount lens.

@the OP : look at your lens bayonet from the rear of the lens. In each of the three sectors of the bayonet you will see a slot. With a tiny screwdriver carefully engaged in those slots, you will be able to get your external mount lens bayonet tighter, by carefully prying out the shorter flange of the bayonet sectors. Be careful neither to scratch the chrome nor to break anything.

The release tab plays no role in making the lens tight onto the camera lens mount, was it with an internal or an external mount lens.

 

[keytarjunkie]

Thanks, I see what you mean about the shorter flange of the bayonet sectors.

The play is on the rotation axis, so I was thinking the problem was where one of the shorter bayonets (at the 4:30 position on the camera body) sits in the lens' track as shown in the photo. There is just a bit too much space between the screw on the left and the lens release.

However, I can't see any way I'd be able to reposition this little screw piece. And looking at my W-Nikkor lens, it looks about the same position. But the W-Nikkor has a noticeably larger gap between the two flanges of the bayonets than these Voigtlander lenses, so I think you must be right. I will carefully attempt to widen the gaps.

 

[css9450]

I recently got an external mount lens (Voigtlander SC Skopar) and the lens is sitting a little loose when attached to a camera. There is too much space between the release tab and the “stop” piece that sits on the other side of the inside of the bayonet.

Is this your first external-mount lens? I am just wondering if what you are experiencing is normal. None of the external-mount lenses I have click into place with the same kind of precise feel that an SLR mount does. They're all a little "loose" in comparison but work perfect and there are no light leaks. The tactile feel while mounting a lens is very different from that of an SLR.

 

[Highway 61]

Is this your first external-mount lens? I am just wondering if what you are experiencing is normal. None of the external-mount lenses I have click into place with the same kind of precise feel that an SLR mount does.

He says he has other external mount lenses, a W-Nikkor for instance which has less amount of play, so I assume he's used to know them. 😉

 

[keytarjunkie]

Yes, I have a 3.5cm f/2.5 which becomes noticeably tighter as it's mounted. This is my first time with these Voigtlander S-mount lenses which are much smoother when mounting and offer no resistance as the red mounting dot points upwards, unlike the Nikkor.

The Voigtlanders are loose enough that the lens mounts move to the left or right as I focus from one way to the other. The Nikkor is much stiffer, and while it seems to have a bit of play if I rotate it, it's much more firmly in place when focusing. That's why I agree with Highway's assessment of the bayonet sectors. I haven't gotten it to work quite yet, but I'm being careful.

 

[css9450]

He says he has other external mount lenses, a W-Nikkor for instance which has less amount of play, so I assume he's used to know them. 😉

Yes, I have a 3.5cm f/2.5 which becomes noticeably tighter as it's mounted.

LOL I skipped right over that the first time.... Stupid eye drops I'm supposed to be using!

I have a Voigtlander 35 so maybe I'll try it when I get home tonight and see if it feels loose too. I haven't used it since I bought my own W-Nikkor 35 so my muscle memory of it has faded (I'm even tempted to sell it in favor of keeping the Nikkor).

 

[das]

Sorry I goofed on what the issue was!

Unless you have a bad example of the lens or body, I would imagine that the looseness is due to VC's chosen tolerances. I would wonder whether the same VC external mount lens would have any looseness when mounted on an R2S or R2C. Every Contax/Nikkor external mount lens I own fits tightly on my S3. You could always contact Mr. Gandy directly about this as well -- maybe he has some insight.

 

[keytarjunkie]

It turns out both these new-to-me lenses have focusing issues (35 back-focuses, 85 front-focuses) so I think they're either gonna go back or get repaired. :bang:

 

[Highway 61]

It turns out both these new-to-me lenses have focusing issues (35 back-focuses, 85 front-focuses) so I think they're either gonna go back or get repaired. :bang:

This sounds unfortunate, especially for the 35, given that I could never see any evidence of misfocusing while mounting a W-Nikkor on a Contax and a Biogon 35 on a Nikon for instance (nor could I while mounting German on German and Nippon on Nippon, of course). Good luck with those badfellow Skopars !

 

[keytarjunkie]

This sounds unfortunate, especially for the 35, given that I could never see any evidence of misfocusing while mounting a W-Nikkor on a Contax and a Biogon 35 on a Nikon for instance (nor could I while mounting German on German and Nippon on Nippon, of course). Good luck with those badfellow Skopars !

I returned them. At a distance of about 3 meters, focus was behind by 1 meter or more on the 35mm. Here are two images at f/2.5 cropped to the center, the red indicates the focus spot.

To me, this was unacceptable. The 85mm did a similar thing but placed the focus in front of where it was supposed to be. I am pretty good with focusing with this camera - I've calibrated the rangefinder well enough to nail the focus with the 50mm f/1.4 wide open at various distances, and I have a few lenses that all work fine. The 85mm also had some scratch marks on the front text ring from a spanner slipping, looked suspicious. It was unfortunate because they were well priced and it is hard to find the 85mm for sale without some haze issues these days.