Repairing a Flektogon 2.4/35mm

richard64 · Joined: 19 May 2008 Posts: 4

I've just bought a CZJ electric MC Flektogon 2.4/35mm lens in 'used' condition. The filter thread is horribly mangled, and the external case was grubby, and rather sticky. I carefully cleaned the outside, and now it is nice and shiny with signs of a little paint loss. I also cleaned the front and rear elements carefully and found them to be clear with only light scratches to the front element. I've taken some photos and the images are good - I love the colour rendition of CZJ lenes!

Anyway, the focussing sticks a bit. I have the same problem with a CZJ MC 135/3.5 too, so I suspect it is a common CZJ problem. Basically the focus gets stiff at close focus. If I rapidly focus in and out for 30 seconds or so, the focusing gets much smoother, so I wonder if the grease in the focusing helix needs replacing.

So, now to my question. Has anyone done this? If so, I would welcome any advice before I get out my screw drivers and start taking it apart! If I do get it apart and cleaned up, what should I use for grease?

Richard

Attila · Expire: 2025-11-18

Nice to see you Richard!
Be carefull with grease! You must use hott ressistant one, if you use normal grease you can risk on hot summer days grease going to the blades.

I have no experience to open these kind of lenses, so I can't give you step by step instruction.

bob955i · Joined: 15 Apr 2007 Posts: 2495

Both the Flek 2.4/35 MC and Sonnar 3.5/135 MC have the same sort of focus helix that is open at the front - if you look between the front barrel and the focus ring, you can actually see it. This makes it kind of prone to picking up dirt and can result in the focus action feeling gritty.

After dismantling and cleaning the threads, I use a small amount of lithium bearing grease and screw the barrel in and out of the helix a couple of times to spread it then remove the excess grease before refitting the barrel in the correct thread.

zewrak · Joined: 12 Apr 2008 Posts: 1212

bob955i · Joined: 15 Apr 2007 Posts: 2495

You can buy differing viscosities of grease for lenses from Microtools at a price.

I just use what I've already got as it's fairly HMP and is temperature stable.

Most problems actually result from overlubrication.

The main key is not to overdo it - I clean out the threads then reapply a small amount of the lithium grease (actually wheel bearing grease) to them and work it into the threads. I then refit the barrel and screw/unscrew it to distribute the grease more thoroughly and displace any excess which I then remove.