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01-25-2010, 01:34 PM   #1
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Anybody attempt lens dismantling?

Hello all.

I am going to be taking apart a lens that I got cheap and has some fungus and a painfully slow apature return. Of course, I don't have a clue what I'm doing, except for the fact that I'm fairly technically savvy and have dismantled just about everything at one time or another.

I'd appreciate any tips or assistance or horror stories, etc., that you've got about your attempts at lens repair.

Thanks!
Tom


Last edited by Moon_man; 01-25-2010 at 02:01 PM.
01-25-2010, 05:52 PM   #2
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Moved to lens forum.

It will help if you tell us what lens it is as they are not all put together the same and some are easier than others.
There have been some quite detailed threads with step-by-step instructions (and pictures) for various lenses.
01-25-2010, 06:15 PM   #3
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QuoteQuote:
I'm fairly technically savvy and have dismantled just about everything at one time or another.
Yeah, but have you put those things back together?

Kidding aside, it was cheap and fungusy, so why not take a crack at it? I've done a little bit of this myself, and my only bits of wisdom are these:
  • Stick to manual-focus lenses, and better yet, manual-everything lenses
  • Beware of tiny things that fall out and have a tendency to get lost, like the tiny springs and ball bearings often used for the aperture ring detents
  • Micro-tools.com has some affordable lens repair tools, like spanner wrenches that can engage the slotted threaded rings that often hold lens elements in place, and cross-point ("JIS") screwdrivers
  • Speaking of cross-point screwdrivers, they are not the same as Philips-head, so beware
  • Sometimes you'll find screws hidden under rubber grips

That's all I can think of at the moment.
01-25-2010, 06:41 PM   #4
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The basic problems are not usually hard to fix. Getting access to the problem can be hard. I have two or three lenses here that I have an idea how to fix, but can't quite get apart. Otherwise, I've been very successful without any real knowledge, just what I've found on this and other sites.

01-25-2010, 06:47 PM   #5
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Couple of points,

aperture clicks are usually a ball bearing held against ridges on a surface under the lens mount that has a spring to apply pressure. when you take out the lens mount, the spring and ball may jump out in a desparate attempt to escape

remove all parts very slowly.

-ake sketches, or take photos, documenting where all the screws go and lable orientation of lens groups. I have seen a few lenses which were perfecctly disassembeled and reassembled except the elements were backwards.
-stick screws to a piece of masking tape and lable them back to the photos showing where they come from
-the lens may come apart from both ends. hence you will possibly need to take both ends apart, especially depending on where the fungus is
-use only the proper size screw drivers
- note that the aperture blades are very thin, and should be dry and oil free. The aperture mechanism is also like a pandora's box to re-assemble, it is best cleaned by stopping down, wiping the blades from one side, opening up and stopping down and cleaning again. Alcohol works for this and use compressed air from a lens cleaning sprayer like dust off to dry the blades and forcce oil oout
- oil comes from the focusing helix, it should be no where else in the lens assembly. everything else should be dry
- use alcohol as a cleaner for the glass and anything while the glass is in the lens body. other solvents can attack lens coatings.
- Be patient, REALLY PATIENT
- some lenses, the entire front group and its mount screw out (vivitar / Kiron wide angle lenses for example) BUT this group may be really tight or locktited in. Look to get a small strap wrench, it is the best way to disassemble these lenses

Good Luck

ps. read other's postings on lens disassembly repair or modification. a lot of people have posted articles like that.
01-25-2010, 08:47 PM   #6
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I've done a few lens "operation" in the past to clean or migrate parts from one to the other.

Make sure you have the proper tools before you start. Precision screwdriver, tweezer rtc.

I recommend laying a piece of white cloth on your designated working area, as losing a small screw can be devastating. At least a cloth will prevent it from bouncing around and white can help you spot it easier.

Yes.. Lots of Patient required.

Good luck.
01-25-2010, 10:26 PM   #7
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These two screwdrivers work miracle for handling those tiny lens screws for me and they are inexpensive. Japanese lens screws are "JIS" which look like Philips but they are actually slightly different. The center of the cross is not round like the Philips. Most of the time, I only need to use the smaller one. But once in while the larger one comes in handy.

Horror stories...I had dropped those tiny ball bearing and tiny spring on the carpet and had to spent hours looking for them.....the tiny ball bearing got stuck to my hand without me knowing and it disappeared...the tiny spring launched like a missile into the air and disappeared....I did eventually found them.

http://www.instructables.com/id/When_a_Phillips_is_not_a_Phillips/step10/JIS...rial-Standard/

IKASWEBSHOP.com -- IKAS, INCORPORATED -- Hozan Tools, Toyo Lint Free, Vessel


Name Code Qty Each Options
-------------------------------------------------------------
HOZAN D-130-75 JIS +00 D-130-75 1 2.95
Screwdriver
HOZAN D-140-100 JIS +0 D-140-100 1 3.80
Screwdriver

Last edited by ma318; 01-25-2010 at 10:57 PM.
01-26-2010, 12:58 AM   #8
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Takin stuff apart

Hi all, put a Katzeye in two weeks ago,live with siberian huskeys that shed once
a year...continuously! Lots of dander. Might help to saturate atomosphere
your working in with plant mister filled with water to settle dust and polarize
suspended particulate to same potental , so that it's less likely to "stick"
like charges repel right. Say maybe 15 minutes before you start your project.

01-26-2010, 02:04 AM   #9
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I found one of those plastic cat litter trays makes a useful workbench and great for stopping screws, springs and other tiny bits from ending up in the carpet.
01-26-2010, 12:48 PM   #10
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The lens I'm thinking about violating is a Auto Sears 135mm 2.8, possibly made by Tokina I've been told. It's completely manual. It was an ebay cheapo-cheapo so if I can't put it back together I'll put one of those spring snakes in it like the practical joke cans and have someone hand me the lens and remove the cap - Zing!
01-26-2010, 03:08 PM   #11
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I would suggest putting screws from each step in an ice cube tray. Working in a cat box (preferably a new one) is also a good idea.
01-26-2010, 08:52 PM   #12
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QuoteOriginally posted by Moon_man Quote
The lens I'm thinking about violating is a Auto Sears 135mm 2.8, possibly made by Tokina I've been told. It's completely manual. It was an ebay cheapo-cheapo so if I can't put it back together I'll put one of those spring snakes in it like the practical joke cans and have someone hand me the lens and remove the cap - Zing!
With the sliding hood? I vaguely remember seeing some tiny grub screws (maybe just 1) on the barrel when it's fully extended. Loosen those and you might be able to unscrew the front of the lens barrel and the hood. I think these lenses also have a beveled trim ring around the front element that unscrews through the filter threads, but it's not necessary to remove that if the barrel unscrews. The ring is very thin, so it's difficult to use the typical friction tool without endangering the front element.

I also remember this lens having a mount like pictured in this thread:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/88151-mount-question.html

I was able to disassemble the rear and unscrew the rear lens group. The aperture blade mechanism is held in by some grub screws that you access through holes in the side of the aluminum frame. I removed the entire thing and soaked it overnight in mineral spirits. Once it dried the next day, it worked great.

Post photos if you have trouble. It was a while ago, I may not remember everything.
01-27-2010, 08:14 PM   #13
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I recently cleaned out an old Tokina 28-200 manual focus lens. It was my first time pulling lenses apart, and it turned out pretty well.
I suggest using disposable rubber gloves (like the surgical ones). Hands are very greasy, and will get grease everywhere!
Some kind of soft rubber device (perhaps an eraser?) makes unscrewing lenses and inner rings easy.
Before you pull a lens out, mark with a pencil where it lined up with the outer casing, and be sure to realign when re-assembling.

Best of luck!
01-28-2010, 05:38 PM   #14
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Many years ago my brother took apart his Petri SLR lens trying to fix it.
He couldn't, and brought the parts to the Petri authorized repair shop.
They told him they had never seen one disassembled that far!

FWIW even a professional repairman I know doesn't like to do zooms...

Chris
01-28-2010, 08:14 PM   #15
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It ain't rocket science but must be done in a methodical way. Your biggest problem is going to be getting the retaining rings off. Lenses are assembled both from the rear And the front.

Get yourself a set of these. They will handle most tasks of removing the retaining rings on lenses.

As you disassemble the lens watch for shims, screws, and springs. These will fall out without apparent knowledge and you'll be wondering why the lens doesn't go back together right. Take PHOTOS and notes. With a fine point pencil, make arrow marks on the side of each element as well as a number noting which in the order it is.

Some fungus will come off with Lens cleaner. Other will require something a little stronger like the Eclips cleaning fluids that some smear on their sensors (it will also remove hazing from the elements). In either case, be prepared for the possibility that it's etched itself into the lens coatings. Some of the element groups are glued together. If fungus has attacked that seal the lens is probably a lost cause.

The sticky aperture. Likely has a coating of oil on it. Even if you cannot see it, it's probably there. The ONLY way to completely clean it is to take it apart. This will be the easy part assuming you can even get it out of the lens (it's probably in the center somewhere). Putting it back together so it works will be a real exercise in patience. This is because aperture blades are stacked on top of one another and are very springy. They are also metal and despite best efforts to avoid it, will become magnatised, making it nearly impossible to use ANY metal bearing tool to put them in place. You can clean the blades with the same eclips used to remove the fungus.

Assuming you get to the point of reassembly, clean each glass completely. Keep your work area as dust free as possible. Check everything for proper fit. It was made to fit together a certain way and should go back together the same way. If you have to force anything, something is wrong.

On the upside, you will know after this experience if you want to mess with anymore hazed or fungused lenses.

Yes, I have a lot of experience with this. Haven't done the Sears lens though. I usually pass them on to somebody else wanting to play with them.

Good luck.
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