Help opening CY Sonnar 85 2.8 MMJ

Trad · Joined: 27 Dec 2015 Posts: 6

Hi, I wish to relube the helicoid on my Sonnar 85 2.8 CY MMJ as the focus is a bit tighter than I like and am looking for advice on how to open her up. I have done this before on my 50 1.7, but need to know before I put a bit more torsion into the right place, if the lens ring unscrews, or if the nose of the Sonnar unscrews to get into the front of the lens. All advice or links appreciated.

vlousada · Joined: 11 Dec 2010 Posts: 345 Location: Portugal

hi,
Some while ago some asked here in this forum:
then was suggested to check this website:

http://forum.mflenses.com/viewtopic.php?t=39653

Hope it helps.

Trad · Joined: 27 Dec 2015 Posts: 6

Thanks for the link, I have seen that, the pics look to me like they show accessing the rear element/aperture. I'm fairly sure that I need to go in from the front, either unscrewing the nose or by unscrewing the lens name ring, then remove the screws that hold the front lens elements, then accessing the focussing helicoid should be obvious. So it's that first step, either unscrewing the nose or the lens ring to access those first sets of screws that I'm looking for guidance on.

Eg on the 50 1.7 Planar you unscrew the lens ring to access the front lens group, kind of unscrews like a filter, which then gives access to the front lens group cage with 3 screws and go from there. You eventually have to open the rear up, much like the link you provided.
On the 28 2.8 Distagon you unscrew the nose (which also gives you access to the infinity adjustment screws), although I've not needed to open her up any further.

So it's the front of the lens I'm trying to unscrew initially and both the nose and the lens ring are tight (that's a good thing), but one of them just needs that bit of extra torsion to unscrew, and I'm not sure which, and I don't wish to inadvertently damage this lens.

Trad · Joined: 27 Dec 2015 Posts: 6

I should add that the infinity adjustment screws on my 50 1.7 AEJ are under the focussing ring rubber, just back them off a bit and make adjustments, that's an iterative process.

The Sonnar also has the infinity adjustment screws under the focussing ring rubber, so it's more than likely that it's of the same type of design, ie I need to get the lens ring off, which is tight. I know that if I drill a couple of small holes either side of the lens ring I'd be able to safely unscrew it using calipers and go from there, but I don't want to do this just yet as it could introduce drill shavings and it is a destructive process that I will avoid. The focus stiffness isn't bad enough for me to do that to this gem.

I got my 50 1.7 lens ring off (this is the front bit surrounding the front lens, that says Carl Zeiss, with the lens number and the lens type) by using a piece of thin rubber glove to give me the grip to rotate it. I've since bought gum rubber blocks in 50 & 55mm diameter for this, but they haven't budged the Sonnar ring yet.

Trad · Joined: 27 Dec 2015 Posts: 6

Quiet day so I tried again to open the front of the lens, to no avail. So thought I'd have a look from the back of the lens.
I took the Leitax adaptor mount screws out (same process if you have say a cheaper bayonnet type adapter i.e. take off the bayonet adapter then carefully remove the mounting screws using a JIS 00 screwdriver), lift off the rear assembly which includes the whole aperture detent assembly (i.e. the detent slotted ring, ball and spring). Take a photograph of the rear of the lens as i have done so you know where the H section aperture lug sat and the relative positioning of the rear assembly to this. You now can see the brass helicoid and by moving the focus ring you'll see more of the helicoid exposed to the rear of the lens as you move the focus toward minimum focus distance. For this Sonnar (85, f2.8 MMJ) you can move the focus through its full range icl. all the way to minimum focus distance and not disengage the helicoid, this exposes about 1/2" of the helicoid - but caution, this is not the case e.g. with the 50 1.7 Planar AEJ, where if you tried this, the helicoid elements come apart....that requires a full disassembly to rectify.

I then used a bunch of cotton tips soaked with isopropyl alcohol to wipe the exposed helicoid thread to clear as much of the old lube as i could access and exercised the focus throughout its range a few times, repeated this a few times until i thought it was clean enough. PS i was using a 5x loupe to check for gunk and any cotton lint deposit that I might be inadvertently introducing. Clean any other dust / gunk you can see, this lens internals were surprisingly clean.

I then applied a drop of Super Lube synthetic oil (with PTFE, Part no. 51004) at 4 points around the exposed helicoid and exercised the focus throughout its range a few times, wiped it clean again with isopropyl, and again lightly re lube. This is one of my helicoid lubricants, and is a very "light oil", say compared to the other lube Ive used - the Super Lube synthetic grease Part no. 21010. Visual check the position of the H section aperture lug which you have probably bumped as you move around the helicoid cleaning, put it back in the place as per your initial pic, carefully lower and relocate the rear assembly over the lens body, put in a couple of screws lightly, check aperture function, put in the other screws and evenly nip them up. Job done.

So the internals that i could see were pretty clean, no dusting, swarf etc that you come across occasionally when looking into these older lenses. The focus now is just as smooth, slightly less heavy, but not a lot of difference, it's nicely damped. I'll probably do this again in 6 months or so, after a bit of use of the lens, to see if i get access to any of the other older lube that might release with what I've done. What Ive done is obviously not as thorough as a full teardown with helicoid clean, but I'm guessing you get access to a good 60-70% of it from the rear like this. Sorry about the poor image, I wasn't looking to "present" this, I just took the shot for my own reference as I pulled it apart.