[ekip]

My lens has a rough spot about half way through the focus throw and has locked a couple of times

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I see a disassembly guide for the V1 but I have the V2 SMC PENTAX-M 1:2.8 28mm version 1 disassembly.

Is this fixable? Would I need to go in from the front or back side?

[pentaxus]

Go in from the front.

[ekip]

What's the best tool to use to get the first part off? Those rubber removal kits cost more than the lens

[Not a Number]

Find a plastic snap on cap like you find on spray cans that is large enough and cover the edge with electrical or friction tape. Duct tape might be too slick but sometimes works. Works like a charm for me. Other people have used rubber drain stoppers if you can find one of the right diameter.

There could be grit or dirt in the helicoid grooves or simple dried up grease that's piled up in a manner to choke the movement.

[pschlute]

What's the best tool to use to get the first part off? Those rubber removal kits cost more than the lens

Find a plastic snap on cap like you find on spray cans that is large enough and cover the edge with electrical or friction tape. Duct tape might be too slick but sometimes works. Works like a charm for me. Other people have used rubber drain stoppers if you can find one of the right diameter.

There could be grit or dirt in the helicoid grooves or simple dried up grease that's piled up in a manner to choke the movement.

I have also had success with large pencil rubbers or double sided sticky pads. it sounds like something (a screw) has come adrift in your lens. Good luck with your repair.

[Just1MoreDave]

Improvising something on this lens should be easy because the name ring is so wide. You don't need to worry about getting too close to the front element. Anything that's kind of rubbery and a >48mm circle s worth trying. If you are careful, you can even glue the ring to a temporary piece with hot melt glue, which should easily come off the ring afterwards. Obviously avoid gluing the font element or the filter threads.

You shouldn't need to remove any elements. Once you get the ring off, you'll see three screws holding the external focus ring to the aluminum internal focus ring. That ring has a fine pitched thread outside (mostly hidden) that threads into the lens body, and very coarse visible threads inside which shove the lens elements in and out. Don't take all that apart, clean off the grease, relube and reassemble. Because you'll be fine until "reassemble". The coarse threads have two or three starting points, plus the fine threads and other parts that need to line up to work correctly. I try to avoid unscrewing the focus threads entirely just to avoid reassembly. That works OK about half the time. The grit is probably obvious and in the coarse threads, because it's easier for stuff to get in there. If you have to disassemble, you should fully understand all the moving parts, take pictures, and mark the parts at the exact point they separate. Otherwise it's a mechanical puzzle to reassemble, easily a couple of hours.

[ekip]

I have the first ring off. I used a roll of electrical tape with cardboard centre to get it off. Now I take out the 3 screws?

[Not a Number]

I take it you have some JIS drivers. Philips screwdrivers are likely to strip the screw heads.

[ekip]

I have some of those crosshead metal precision screwdrivers and the #0.3 fits ok but the handle is really small and I cant get much grip on it.

The screws are really close to the edge too. It looks like they are glued in?

[Not a Number]

Yes it looks as if thread lock/varnish was applied. It should break easily enough if you use JIS drivers. Philips will "cam out" (by design) and likely strip the head before loosening the screw. You could judiciously apply some acetone or heat with a soldering iron to soften the thread lock.

Cross-head screws - a caution: - PentaxForums.com

[ekip]

Thanks for the help. I can see a bit of the coarse thread and fished out some tiny bits of crud floating around but the problem is still in there. I guess the next 3 screws link the focus ring to the inner lens group? I guess I have to return these next screws to the same place to retain infinity focus?