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04-10-2011, 07:29 PM   #1
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Success - Oily Blades, Clean and Snappy

Hi,

I thought I’d introduce myself by sharing my success in fixing an older lens. I guess it may be construed a little bit as gloating, but I can’t help it, this is pretty darn exciting.

I received a lens off of Ebay earlier this week; Pentax-M 1:4.5 80—200mm. The seller called it “minty”, but neglected to note that the dent on the lens affected the focusing and that the aperture blades were very oily. You could clearly feel the dented tube when focusing or zooming. The aperture blades would not budge closed when released.

The seller had a 7 day return policy which I considering; weighting the pros and cons. I only paid $15 for the lens and a whopping $10 in shipping. Despite not coming with either lens cap, the glass was beautiful; saved mostly by the marred UV filter. So, obviously in the end, I decided to try to fix the lens; considering the cost to be tuition. I was encourage by several postings on this forum and figured I had little to lose.

I’m happy to report that after numerous hours (I’m rather slow and plodding), the lens is back together and is working great. The easiest thing to fix was the dent. A few careful, well placed whacks with a small ball peen hammer to the inside of the tube and the dent no longer interferes with the internals of the lens. Fortunately, this tube (it’s the one with focal length numbers on it) needed to be removed to get at the aperture diaphragm.

I took apart way too much to get to the aperture diaphragm, but eventually I got the little bugger out. I cleaned it up with alcohol; dissembled too much; reassembled it; dissembled the right amount; lubed it with a little graphite lube and reassembled it. It now has a satisfying snap when it’s released.

I do have a few tips to pass along that I haven’t seen before; there’s no sense keeping by tricks to myself. The hardest part of this project was stubborn fasteners.

1) Get a #000 phillips head driver (included in a $8 set at Harbor Freight); my only expenditure for this little task. My other precision screwdriver sets did not include a #000. All of the Pentax phillips screw heads required this size. Note: A flat blade slips out too easily of phillips heads.

2) Pentax likes to add glue to secure the screws. Clean out the glue from the head of the screws. They’re tight enough; you don’t need your driver slipping out because it can’t make full contact with the slots.

3) For the really tough screws, I used a “hot wrench”. One of the screws and the ring on the aperture were glued on tight. I used a Bic lighter to heat the material of the female portion of the threaded interface. I was very careful, and you should be as well, to not over heat the material. I kept the temperature hot to the touch but below the melting temp. of the paint. This may sound risky, but I had to do something and it did work.

4) The blade of a thin paint scrapper was able to span the notch of the ring on the aperture assembly. It had the same type notched ring used to retain the lens. Because it was also glued, I heated up the mating tube that the ring screws into and I wore rubber gloves for extra grip. After much grunting, it loosened.

5) Take picture as you go. Even crappy ones can help you figure out what screws go where.

So, thanks for reading my little story. The only downside of this little adventure is now my LBA is emboldened. On its way to my house is a Pentax-A 1/1.7 50mm with a bad aperture ring. The boot shoe box with my tools is all ready.

Jim


Last edited by MountainManJim; 04-10-2011 at 08:12 PM.
04-10-2011, 08:18 PM   #2
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A very interesting read, thanks for that. I don't know that I would have the dexterity handle a repair job like that, so congrats, well done.

I have to say the 80-200 is a rather good lens for what it is. I had one given to me, and, other than a bit soft at 200mm end, it turns out some very respectable results.



Best of luck with your "new" lens.
04-10-2011, 08:37 PM   #3
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Bramela,

Nice pic. That's pretty nice, considering the close focusing distance of the Pentax 80-200 doesn't seem to be that impressive.

I kind of like this new lens, but I need some more time with it. I think I'm just excited. I was thinking it would be better than my Vivitar Series 1 (3rd prod. run) 70-210 mm, but the jury is still out on that. I might use it as my hiking lens since it's a lot lighter than the Vivitar.

Jim
04-10-2011, 08:38 PM   #4
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I'm glad to hear your story. I have a lens with a bit of hazing near the rear glass and the view finder on my DL has some hazing also I am planning on attempting to clean them starting with the lens which I have almost nothing tied up in. If that goes well next the top comes off the ist.If not then the camera goes into the shop.

04-10-2011, 08:42 PM   #5
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Wow, taking apart the camera ... Good Luck!! I'm sure it will be fine.

Jim
04-10-2011, 08:57 PM   #6
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Sounds cool, I've got a Sears 135mm with some fungus that I was thinking about taking apart to fix.

Some pics of the lens in the different stages would be interesting to see.
04-10-2011, 09:01 PM   #7
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A-Craig,

Unfortunately, I took my own advice and took some really crummy, low ambient light pictures. They are really not presentable

Jim
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