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John_shriver
Tinkerer
Username: John_shriver
Post Number: 54
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 09, 2010 - 08:57 pm: | 
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Having worked on a few Pentax-A lenses, I've found that they have a pattern for dis-assembly. You remove the dress ring, and the filter ring is then held in by four screws. When you remove the filter ring, you can then see the three or four screws that hold the focusing collar in place, the position of which relative to the helical sets the infinity stop.
Are Pentax-M lenses generally built along this same pattern? I have a Pentax-M 85/2 with a dinged up filter ring (mostly straightened), whose focusing collar is rotated. It stops at optical infinity, but not at infinity on the scale. Do I start by removing the dress ring with a rubber stopper, just like the Pentax-A lenses? Or will it really be holding the glass into the barrel? |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 56
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 17, 2010 - 06:53 pm: |
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Well, I just got a Pentax-M 35/2.0 with an oily diaphragm, and it certainly comes apart pretty much the same as a Pentax-A 28/2.8.
Looking with a magnifier, it does look like the Pentax-M 85/2.0 is built in this same way, but things look a lot tighter.
Anyone know if the filter ring section of that lens is the same as any other Pentax-M lens? (Hopefully one that sells cheaply.) It's longer than many. |
Hamesh
Tinkerer
Username: Hamesh
Post Number: 1
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 23, 2010 - 11:22 am: |
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I cleaned the internal element surfaces of dust on mine some time ago and it was easiest to remove the rear element group. It comes out as a single grouping right up to the aperture blades. You might go this route first.
You can also go in from the front but it requires that you remove the dress ring with a stopper as you suggest. Then usually three screws to remove the group right back to the aperture rings. Just try to avoid removing the helical. |
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