CV Color Skopar 35mm f/2.5 Optical block loose

[fedka]

I just bough a Voigtlander Color Skopar 35 mm f/25, M-mount version, looks like the latest design type.
The lens has a seized lens hood and its previews owner tried to unscrew it (unsuccessfully) and after this the whole optical block rotates (when you grab it by the metal front/filter ring/bayonet). I did remove the hood, and want to secure the block now.

It looks like there is a retaining ring that can be seen from the back, and it rotates with the block. I tried to tighten it with a spanner, but it was tight already, did not move.

Is there anything else that hold the block in place? Maybe a set screw? How do I get to it?

Thank you,
Yuri

 

[ferider]

There are several rings in the back, use the right one (the outermost).

Take the span ring out. The optical block will pull out in the front. It has a screw that holds it in position (with a respective gap in the focus helical). Maybe that sheered off ? Also, there are typically brass collimation shims, that have the same gap, make sure they sit correctly.

Roland.

 

[Ko.Fe.]

All hail to Yuri!

I've had Color Skopar-M 35 2.5 PII which developed loose lens block issue after year of extensive use. I can't find thread here which shows which ring needs to be tighten.
But I remember it wasn't the one I would think of.

 

[fedka]

Just to confirm - as long as I keep all the shims in place I will not disturb the lens adjustment?
Sheared something came to my mind too, since I feel some sort "grabbing" when I turn the optical block.
I'll try this tonight. Not sure what to do about the sheared screw (it is is the case), but at least I'll see the reason for this

 

[ferider]

Just to confirm - as long as I keep all the shims in place I will not disturb the lens adjustment?

Yes. Good luck !

 

[Ko.Fe.]

Somehow I ended up with taking apart focusing part of this lens to fix loose screws holding focus tab.
Getting at all back wasn't problem.

 

[fedka]

Unscrewed the retaining ring, pulled the block out. At first I could not see anything that would hold the block in place, then discovered the pin that was sheared, apparently when they tried to remove a stuck lens hood (was lodged in one of the crevices).
On the picture below - from left to right: focusing assembly with the retaining slot, pin with broken off threaded part, block with the threaded part sheared.

I decided to think about the repair later and assembled the lens. I tighten the retaining ring and the block is quite firm in place, fully usable. So I'll just use the lens as is. Having that nice stack of shims (4 thick and one super thin) makes me comfortable in believing that the lens is still at factory adjustment.

It is a sharp lens, btw.

Thank you Roland and Kostya.

Yes. Good luck !