Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-24-2012, 10:39 AM   #1
New Member




Join Date: Apr 2012
Posts: 12
135mm f2.8 M42 Auto Chinon Disassembly

Hi forum!

My M42 Auto Chinon 135mm f2.8 is developing some fungus and I feel like I'm in a race with time to save this beauty!

I've finally been able to figure out how to remove the whole focus mechanism. Tricky lens, unlike the smaller 50mm ones. The lens hood was a particularly surprising maneuver.

Anywayz, I now have a lens assembly that seems to be entirely glued (not as in cemeted lenses, but as in glued spacers and glued metal threads and glued glue and everything) so nothing turns anymore and I still cannot remove the front element.

I've successfully got myself a couple cuts and plasters on my fingers just trying to turn the front element out, unscrew it, but it still won't budge.

I've been googling glue removals and there were some suggestions like using acetone and boiling water and other chemicals and whatnot, but I'm not sure any of that is suitable for multi-coated optical elements.

So there. I have no idea what to do now, and having reached this forum from google, I think my best bet is to post my question here, since there seems to be many fine members with the proper knowledge to do such things.

So HEEEEEELP!

I've posted a couple pictures showing the lens assembly without any mechanisms. The aperture mechanism is still at the bottom but i don't think I'll get anywhere by tampering with that. The front element is the way to go. The red arrow in the picture points to the thread of the front element, which won't turn no matter how hard I try.

Hope to find a quick answer as I do not like the sight of those nasty fungi growing in my lens.

Attached Images
   
04-24-2012, 11:28 AM   #2
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
The ring is too thin and when put pressure on its side you deform it and it stucks to the thread...try to unsrew it from the top by using some rubber material which is thick enough (around 10 mm) which you can press and which has enough coefficient of friction to stick to the ring and to the lens element.
Put the rubber on the element, put some pressure and try to unscrew.
Good luck!
04-24-2012, 11:36 AM   #3
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Thank you for your reply Vasyl. That was exactly what I did.

I used rubber bands, thick ones, to hold the assembly, one was around the ring I was trying to remove, and one was at the bottom before the diaphragm mechanism. I kept them at a distance to that any one of two possible threads would turn. Nothing did! It's like the whole thing is one solid tube, which i know it isn't!!

I can see if I reflect some light on the thread that the dry glue shimmers. It's there, in between the threads.

I found a couple suggestions. One says that this glue in old lenses was Canada Balsam, which will break in the heat of boiling water.
One suggested using acetone, and another suggested other chemicals.

I'm actually worried about the lens coating if I use any of that, especially the most readily available method of boiling water.
But then I don't know if there are any cemended optical elements inside, and I definitely don't want those to break either!

So the thing won't turn using rubber bands, and I'm looking for suggestion to deal with the thread glue.

Thanks in advance to anyone who can give me a couple cents.
04-24-2012, 12:41 PM   #4
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
That is not what I meant...
The rubber plate should be put on top of the lens and the ring. Then you press it to the lens element and the ring and rotate to unscrew...

04-24-2012, 12:44 PM   #5
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Oh, you mean like rubber donut rings used to turn optical elements by pressing on their surface. I think I can find a picture on google images somewhere.

http://www.personal-view.com/talks/uploads/FileUpload/65/5b0581fed13f98ac9038e8231c968c.jpg

I used one like that to remove the original protective ring that has all the info written on it.

But it never budged the lens itself.
04-24-2012, 12:44 PM   #6
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
by the way...you can use break liquid from your car it is:
a) a good solvent
b) perfect penetrator through the cracks...

Just use a pipette to put a couple of drops around the ring and put it upside down (front element down) for the liquid penetration.

Good luck!
04-24-2012, 12:46 PM   #7
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Oh great, now I have to buy a car just to remove the lens front element!!!!

lol

Thanks. I'll ask if someobody can lend me a couple break liquid drops. Do you think acetone will work on this?

Do you know what I SHOULDN'T try in order not to damage the lens coating???
04-24-2012, 01:15 PM   #8
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
Oh I am sorry...I thought the car is part of the lens...:-)

Acetone will not work...unless you put the entire piece in it...I would not ...:-)

I can even try WD-40 to apply in the way as I described above.

04-24-2012, 01:23 PM   #9
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Thanks, I'll give that a look.

Here's another thing I'm thinking. After actually opening the lens. I'm gonna clean the newly forming fungus threads and whatever chemical they have been producing. Now if I use mould-attack or other chemicals designed to kill mould spores in order for them not to come back that easily, will that affect the lens coating???
04-24-2012, 01:26 PM   #10
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
Oh, I am sorry, I thought the car is part of the lens...:-)

Acetone will not work unless you put the entire piece in it...I would not....:-)

You can try any liquid if you apply it on the thread in the way as I described above...By the way WD-40 might work too.
You can even use simply any mineral oil (oh I forgot you have to buy a car), it is cheaper than buying a car...:-)

Just remember the problem is not with the lens but with thread that is why you have to apply the liquid on the thread and allowing it to penetrate through.

Good luck!

P.S. I assume the next thread will be what to try to remove the fungus and how to recover the coating...:-) What I faced with just recently, if you have fungi it damages the coating (at least it happened in my case) if you even remove it, you will have spots. The spots are just uncoated glass which left by the fungi. While living they produce acid which destroys the coating.
04-24-2012, 01:28 PM   #11
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
Ha-ha-ha))))))))))
I was right...I used hydrogen peroxide solution it is the best fungi, bacteria killer.
04-24-2012, 01:47 PM   #12
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
lol, seems like a common dilemma. Fortunately, the spots are still peripheral so they shouldn't have any effect on images.

I'll look that hydrogen peroxide thing too. I have a solution that utilizes benzalkonium chloride, and one that contains w/w QUATERNARY AMMONIUM HALIDE. That's what it says, in capitals. Sounds dangerous.
04-24-2012, 01:57 PM - 1 Like   #13
Veteran Member




Join Date: Aug 2010
Photos: Gallery
Posts: 414
benzalkonium chloride is the Quaternary Ammonium Halide...
Be careful it stucks to the surface...
This material is used everywhere...even in hair conditioners...
In terms of its impact on glass, be careful, it stucks to the glass awfully streaking...
04-24-2012, 02:08 PM   #14
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Oh really? It didn't have any effect on my window glass! Maybe on the coating material though. I'll probably just swipe them with water for starters while I find the hydrogen thingie.

I'll still have to open the lens first. <_<

Thanks for all the great info.
05-02-2012, 04:13 AM   #15
New Member




Join Date: Apr 2012
Posts: 12
Original Poster
Hi forum! Just to let you know. I went for the WD-40 solution, and true enough, I opened the lens and removed the front (and middle) elements.

Thanks a lot for that suggestions, Vasyl!

Then I just gave it a basic clean without using any solutions. I just cleaned the spacing rings with anti-mould solution, but not the optics. And the effect of fungus on the coating is limited to the edges anyway, so that's still invisible.

Time to put the lens back together. I put everything in place, and threaded the previously troublesome thread-ring in place, but I found out that the front element is still shaking a little inside. There shouldn't be any extra space if everything is right, right?

So I either have something wrong, which isn't likely, or that the glue which I removed to open the ring was actually holding the element in place too!

Anyway, I just lost the aperture spring yesterday, so until I find a replacement, the lens stays open. <_<
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
135mm, auto, couple, element, front, glue, k-mount, lens, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
[SOLD]Auto Chinon (Revuenon/Tomioka) 55mm f/1.7 m42 lens dcshooter Sold Items 6 03-29-2012 03:51 PM
For Sale - Sold: M42 Super Taks 50/1.4, 135.3.5, Auto Chinon 28/2.8, M42 adapter,Sun 2x tele converter olivemike Sold Items 3 12-18-2011 04:18 PM
Chinon 135mm f2.8 M42 BeerBelly Troubleshooting and Beginner Help 4 02-03-2011 11:54 PM



All times are GMT -7. The time now is 05:10 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top