[Kerrowdown]

I say, you are a braver bunch than me, there's me just thinking thats what repair shops were for.

[deepbluish]

And that's exactly what I'm gonna do. It seems the lens will be in a repair shop on Monday and we'll se how that goes...

[tomypreach]

Found this site , on a different tread

Disassembly and Cleaning of the F1.4 50mm Super Takumar Lens

Great site !!!

[newarts]

Yesterday I began to disassemble a Canon FD lens to investigate converting it to Pentax-K.

On loosening the second screw mounting the lens' flange I heard an awful "sproing" sound as an internal pre-loaded spring released! Uh-Oh!

I'm glad I don't have to re-assemble this lens!

Good luck!

[cyclingshooter]

Well, I didn't really have that amount of disassembling in mind, just enough to clean the blades without removing them

I seriously doubt that even if I managed to completely disassemble a lens I would manage to reassemble it so that it actually works

That's why my advice to you (and myself) is don't do it

[deepbluish]

Just to post some feedback....

In the end the lens was at a repair shop and the blades are now clean and snappy. But, the repairman seems not to have much experience with these lenses with A contacts and somehow managed to screw things up. Now, my lens is still an A lens, the contacts work fine, but the funny thing is that now the lens is ONLY A-type lens. More precisely, even if I move the aperture ring to any position, f32, f8, f2.8 or whichever, the lens still acts as if it were in the A position. I don't mind it that much though, it's not that I plan to use it on a film camera with no electric contacts, and I certainly don't plan to sell it...

I guess this would be an easy fix for someone who knows how to deal with these things, but I think I'll just leave it as it is....

[wavecurrent]

Well guys, I guess I got inspired after reading this tread, so yesterday I took almost completely apart my old Pentax-M 35mm F2.8 (have had it since it was new) due to the slow aperture, was some grease on the blades (I think it’s known for it’s sticky blades). It wasn’t actually too hard. You first unscrew the front ring with a friction tool and the remove the 3-screws underneath, then the front lens assembly can be unscrewed (turn the focusing ring to the close focus limit for an easy access). Then turn it around and remove the bayonet mount, leave the plastic cover on the bayonet. Now you have access to the rear lens assembly, unscrew it, and now you can access the aperture from both sides. Now from the front unscrew the ring holding the aperture mechanism in place, and remove the screws holding the aperture level in place. The picture below shows the 35mm in pieces, well after reassembly of the pieces the lens is as new again.


After this success started working on my old favourite lens from the film days, the M20/F4. It had also developed a slow aperture during the years, the work flow is basically the same. But I didn’t dare taking the aperture mechanism apart, so I used some electronic cleaning spray on it. It worked very well, the old favourite is back in working order again


Another thing that will cause the aperture to work slowly: is a kind of a step-down ring located between the bayonet and the lens itself. I guess old and excessive amount grease on this ring will make the aperture work slowly as well, both the K28/F3.5 and the K35/F3.5 I have, had this problem. But now both of them have a snappy aperture again. I guess I have to put some light grease on the ring again to relubricate it. The picture shows the K35/F3.5 after the bayonet have been removed.


If any of you need some more pictures of any of these lenses, I can put them on my Flickr page

Regards,

Mike

[frank]

Well guys, I guess I got inspired after reading this tread, so yesterday I took almost completely apart my old Pentax-M 35mm F2.8 (have had it since it was new) due to the slow aperture, was some grease on the blades (I think it’s known for it’s sticky blades). It wasn’t actually too hard. You first unscrew the front ring with a friction tool and the remove the 3-screws underneath, then the front lens assembly can be unscrewed (turn the focusing ring to the close focus limit for an easy access). Then turn it around and remove the bayonet mount, leave the plastic cover on the bayonet. Now you have access to the rear lens assembly, unscrew it, and now you can access the aperture from both sides. Now from the front unscrew the ring holding the aperture mechanism in place, and remove the screws holding the aperture level in place. The picture below shows the 35mm in pieces, well after reassembly of the pieces the lens is as new again.

...

That's almost exactly what I did on my first lens surgery Well, mine was a cheap cosina though, so I didn't really care if I couldn't put the mess back to order.

I'm waiting for an A24/2.8 from a forum friend who also claimed slow aperture blades movement problem, hopefully the A lens isn't too difficult to reassemble.

[Arjay Bee]

I have also done a few of these but have more problems with residual dust and film on the lenses than with the mechanics when reassembling.
Do you guys use cotton gloves while handling the lenses (or are my fingertips just super oily)?
What cleaning cloths/tissues do you use? My cloths seem to leave a streaky film on the lens when examined at flattish angle under my flouro desklight altghough seem okay when viewed straight on. Lots ofrocket blower use to make sure atmospheric dust doesn't get in there.
A tip I got from someone here a few months ago is to mark an arrow on the edge of the lenses with a pencil to show the direction it should face when reassembling. Some of those tricky little doublets have differing curvature on each side.

[Jewelltrail]

Frank: Here you can find step-by-step on how to strip down a Super Takumar 50/1.4 lens:
Pentax 50mm f/1.4 strip-down instructions

And here is a link on how to open up an M50/2 lens:

Thanks Frank--this is a nice resource to have in ones favorites.

tomypreach
Found this site , on a different tread

Disassembly and Cleaning of the F1.4 50mm Super Takumar Lens

Great site !!!

__________________

And thanks Tomypreach as well for another nice favorite!

[wavecurrent]

I have also done a few of these but have more problems with residual dust and film on the lenses than with the mechanics when reassembling.
Do you guys use cotton gloves while handling the lenses (or are my fingertips just super oily)?
What cleaning cloths/tissues do you use? My cloths seem to leave a streaky film on the lens when examined at flattish angle under my flouro desklight altghough seem okay when viewed straight on. Lots ofrocket blower use to make sure atmospheric dust doesn't get in there.
A tip I got from someone here a few months ago is to mark an arrow on the edge of the lenses with a pencil to show the direction it should face when reassembling. Some of those tricky little doublets have differing curvature on each side.

I don't remove the lenses at all, unless I really have to! With the M35/2.8 and the M20/4, you can quite easy unscrew the front and rear lens assembly without touching the individual lens elements. So it's only four lens surfaces all together.
I'm using a type of rocket blower for cleaning them, and some thin rubber gloves when handling the lenses.
I also use some good quality tools for the screws, mostly phillips point screws size 0 and 00, otherwise you will damage them.

Mike

[Ben_Edict]

I have also done a few of these but have more problems with residual dust and film on the lenses than with the mechanics when reassembling.
Do you guys use cotton gloves while handling the lenses (or are my fingertips just super oily)?
What cleaning cloths/tissues do you use? My cloths seem to leave a streaky film on the lens when examined at flattish angle under my flouro desklight altghough seem okay when viewed straight on. Lots ofrocket blower use to make sure atmospheric dust doesn't get in there.
A tip I got from someone here a few months ago is to mark an arrow on the edge of the lenses with a pencil to show the direction it should face when reassembling. Some of those tricky little doublets have differing curvature on each side.

Arjay, I handle lenses usually with cotton gloves, but clean them before reassembling with Pec-Pads and Eclips. That takes care of all fingerprints or smudge and doesn't leave any residue. Also the Pec-Pads are lint-free.

If you have a a small number of dust flecks between your lenses, simply forget it. It has no influence on the image and is quite normal for older lenses. Dust will find its way anyway into the lens, sooner or later...

On the other hand: Lens assemblies shouldn't usually be disassembled. Reassembling is not only a matter of joining the correct curves. If you have a high quality lens, the single lenses might have been centered manually during the production. In that case it is not only important to have the right sides of the lenses facing each other, but also the angle of rotation between lenses! This is nearly impossible to achieve yourself, unless you have an optical bench and some measurement tools (and knowledge, how to use them). When cleaning photographic lenses or their mechanics it should usually be sufficient to work with the whole lens groups and there should be no need for disassembling to the single lens.

Ben

[jensm]

Anybody experienced with doing this to a K 24/2.8? From the outside, it looks almost identical to the M 35/2.8, so I suppose there is a chance that internal assembly is more or less the same.
/Jens

[wavecurrent]

Anybody experienced with doing this to a K 24/2.8? From the outside, it looks almost identical to the M 35/2.8, so I suppose there is a chance that internal assembly is more or less the same.
/Jens

Yes, I have taken a K 24/2.8 apart. And it's almost the same as the M35, the rear end is actually a little bit simpler in its design. The reason was that I suspected some fungus in the front lens grope, but I think it's even worse. There are two lenses cemented together, and they are coming apart
Look at the pictures, what do you think??!!


Mike,

[ovim]

Haven't done it myself but heres a thread on mflenses.com on repairing cemented lenses.