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02-14-2013, 03:05 AM   #1
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anyone fix lenses?

So here's my problem. i have a pentax a 28 f 2 lens with a really messed up filter ring. i tried to fix it with the lens vice and mangled the threads to the point of no return. is there a way to remove the filter threads and replace with a whole new assembly? i did with the konica 50mm lens. funny thing was that was my practice lens and i got that one right and ended up mangling my pentax lens

02-14-2013, 03:36 AM   #2
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I believe it can be replaced, if it is similar to the ones I've taken apart. The hard part will be removing the trim ring to access the screws to remove it, since that trim ring goes into the filter threads. You might have a challenge finding a replacement for that lens, if you're lucky it might share that part with another more common lens.
02-14-2013, 03:53 AM   #3
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You may have to snip into the ring to bend the bad bits away enough to be able to unscrew the name trim cover. To get the trim ring off, I have a number of small bottles with different size openings. When I find the right fit, I use double sided tape to cover its opening. Then I make sure the centre bit is covered with something to prevent sticking to the lens. It really works well because the grip is so good. Be very careful trying to get the trim ring separated from the tape afterwards or you will damage it.
The filter ring is usually held on with three screws. If you can figure which they are, remove them and the ring will come free. Find a junk 49mm lens and use it's filter ring as a replacement.
02-14-2013, 04:07 AM   #4
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QuoteOriginally posted by arnold Quote
You may have to snip into the ring to bend the bad bits away enough to be able to unscrew the name trim cover. To get the trim ring off, I have a number of small bottles with different size openings. When I find the right fit, I use double sided tape to cover its opening. Then I make sure the centre bit is covered with something to prevent sticking to the lens. It really works well because the grip is so good. Be very careful trying to get the trim ring separated from the tape afterwards or you will damage it.
The filter ring is usually held on with three screws. If you can figure which they are, remove them and the ring will come free. Find a junk 49mm lens and use it's filter ring as a replacement.
are the filter rings universal for all 49mm lenses?

02-14-2013, 05:36 AM   #5
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finally got the beauty ring off the busted filter... i had to gouge two slots so i can use my spanner wrench to get it out . time to search for a new set of threads.
02-14-2013, 07:14 AM   #6
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Dare I ask, what were you doing in the first place to that fine piece of glass, to end messing up the filter ring?
02-14-2013, 08:37 AM   #7
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I've had luck using whats called a Thread File. It's a square tool, one ends 4 course thread sizes, the other 4 fine thread sizes. The fine end worked on Pentax 49mm threads. Not common but you should be able to find one at a Real tool store, not Home Depot or Autozone.
I first used a blade to remove any loose material. Then placing the end of the tool on the threads, found the correct thread per inch size. It was then just a matter of putting the file on the undamaged threads and slowly working it thru the damaged area. Took about 15 minutes in my case. The threads won't be perfect but they will work. Good Luck.
02-19-2013, 02:43 AM   #8
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the filter ring was dented, and i was trying to undent it with a tool i got off ebay. i replaced the whole front end with a 49mm thread from a pentax m 50 f2 but its short. the only other filter ring assembly that looked like it even came close to the distance was the 50 1.4. but at 140 dollars it was too much for the part. pentax canada hasn't gotten back to me yet about the beauty disc or the filter thread assembly. I ended up sticking a 49mm to 55mm step up ring and removing the beauty ring all together. BUBBA STYLE

02-19-2013, 07:39 AM   #9
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Yes, a lens vise can easily do more damage than it solves. You need to use one gently or the lens rim can deform, stretch and be ruined. Use it just enough to allow filters to mount - some deformation will remain.
02-19-2013, 04:15 PM   #10
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I did save a lens with two bad filter-ring dents, by hollowing out a bit of wood with the correct radius using a filter for profile. I then carved another very small bit with the male part of the curve. The idea was to sandwich the deformed section between the two. Making sure the lens was supported, I used a third piece of hard wood as the force applicator, placing one end against the male piece resting on the deformed section of lens. I then used a light hammer to tap the other end, increasing the force slowly enough to ensure only enough was used to correct the deformity. I was very pleased to see that I was then able to remove the beauty ring, and later add a filter. Only a slight bit of tightness in one area indicated there had ever been a problem.
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