Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-05-2013, 04:26 AM   #1
Inactive Account




Join Date: Jul 2013
Posts: 18
Mamiya / Sekor 55mm 1.8 - Repair/Dissassembly advice

Ok - so I've got one of these lenses - yet to try it yet.
Just acquired one, fairly cheaply.
But it has an issue.
Although it's free from fungus, and there doesn't appear to be any scratches on the glass anywhere, the focus ring does appear to stick quite a bit at a couple points in the rings travel.
On closer inspection, it looks like it may have taken a bash at some point, so that the barrell has a very slight flattened are on the outside.
I should have taken a photo to highlight it.
Anyway, I think this slightly deformed area (and possibly also a bit of flattening on the focussing ring barrell), is causing this slightly jarring focus action.

So, I'd like to dismantle the lens slightly, to try and sort out these flattened areas.

Problem is, I've found no sources online so far to illustrator how to do this.

I have managed to remove the name plate round the lens on the front - but that's as far as I've gone.
I really don't want to go into this unprepared as I've read it's a very decent lens, so I don't want to render it useless because I've gone into this too hastilly.

So, any help would be great!!!!

I think the main issue I have is removing the focussing ring - if I can get this off, it should give me a bit of room to try and add a curve again to the areas taken a bash, and thus hopefully making it easier to turn the focussing ring...


Last edited by LensMagnet; 08-05-2013 at 02:54 PM. Reason: Clarification
08-05-2013, 12:31 PM   #2
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
So, I took some shots to highlight what I've done, so far.


NAME PLATE REMOVED par LensMagnet, on ipernity


TWO SCREWS par LensMagnet, on ipernity


DENT1 par LensMagnet, on ipernity


DENT2 par LensMagnet, on ipernity


SMALLER SCREWS par LensMagnet, on ipernity

Last edited by LensMagnet; 08-05-2013 at 12:33 PM. Reason: embedded image screw up
08-05-2013, 12:37 PM   #3
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
Ok - so as you can see I managed to get the name plate off - and I thought I'd see what happened if I took off the 3 screws behind the name plate, and the 2 screws on the side.
The lens seems just as structurall sound as it did before I removed the screws lol.
However - it's got me thinking if I should be removing any of these at all.
Should I just be attacking the small screws on the side instead?
These appear in 3 groups of 2, either side of the aperture ring.

What should I do?

I've highlighted where the screws were before in green.
And in two shots it should be fairly obvious where the flattening, and dents are that I want to try and smooth out.

Also - I've read on other listings that there's a tiny small ball which can be lost easily which is required for setting the aperture - when should I keep an eye out for this?

Cheers!
08-06-2013, 01:08 AM   #4
Site Supporter




Join Date: Aug 2012
Location: Perth, Western Australia
Photos: Gallery | Albums
Posts: 296
Hi
I don't have experience with this lens, but have taken apart (and put back together!) some Takumars.
The little ball bearing will be under the aperture ring...it provides the click stops when adjusting aperture. So, if you remove the aperture ring that's when you need to watch out for it.
I imagine it's quite similar to the Takumars...this a page I found helpful...
Pentax 50mm f/1.4 strip-down instructions
Cheers
Dean

08-06-2013, 02:24 AM   #5
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
Thanks for the reply Dean.
OVer 100 views, and not a single reply, so thanks for your response!
Curiousity got the better of me, and I just removed all the screws I could get to.
I'll take some more shots tonight, but I've managed to remove the lens from the housing.
I nearly lost the tiny ball as well - didn't realise where it was, but when you remove a few of these screws the thing tends to fall apart.
So, without me even realising it, the rear plate (not the part with the M42 screw thread) came away, to loosen both the aperture ring, the switch, and the ring with the printed numbers.
I want to get at the ring with the printed numbers to smooth out the flat area, but I can't seem to work out how to do this.
There must be some way of doing it.
The lens section just fell into my hand from the focussing ring area (is that called the helicoid?).

This stuff isn't easy, is it?
08-06-2013, 02:40 AM   #6
Site Supporter




Join Date: Aug 2012
Location: Perth, Western Australia
Photos: Gallery | Albums
Posts: 296
Yeah, it's a learning experience for sure.
Seems like the Mamiya is a bit different from the Takumar...
In your first picture the three screws immediately under the name ring would have been what I would guess held in the focus ring you are wanting to get at. Pretty sure that does the trick on the Taks.
Is there any play on the focus ring? Does it feel like you could "angle it out" at all? Do you think the dent itself is holding it in place?
Well...good luck...wish I could offer more advice...when you post some more pics I'll have a look and see if there is anything else I can comment on.
Cheers
Dean
08-06-2013, 02:55 AM   #7
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
I have a feeling that the 3 screws behind the name plate hold in the optics.
I could be wrong though.
When I initially removed those screws, nothing appeared to happen but maybe some of the rings (aperture ring etc) also help to keep the optics in place.
When I removed ALL of the screws - ie 3 behind name plate - 2 on focussing ring - 3 groups of two either side of aperture ring - everything sort of became loose.
I actually thought the optic was held in place, only for it to almost drop completely out of the rest of the housing when I was playing about.
I thought it was still held in place.
I take it the aperture blades are also held within the optic part?
It was getting late last night, and I don't have a proper sort of angle poise lamp, so couldn't investigate what was going on further...
08-06-2013, 08:16 AM   #8
Junior Member




Join Date: Jul 2011
Location: Northern California
Posts: 27
I have one of these lenses that sustained damage as well, but haven't any advice to give. I left mine alone due to the damage being confined to the filter threads. My guess is that the helical might be out of round along with the focus ring damage. Most MF prime lenses I know of are constructed so the elements/groups come out and the aperture blades remain with the barrel.

08-07-2013, 01:03 AM   #9
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
So here is it's current status.
Can't work out how to remove the focus ring - or the switch to get to the number ring to try and smooth out the dent.

Removed Ring/Plate (with small ball)


P1030271 par LensMagnet, on ipernity

Ring/Plate (with spring detail and small ball on right)
Note, the ball isn't attached to anything - it has a small amount of gunge on it which is holding it in place slightly, but if bashed when moving it, I reckon that ball would be lost. I've already thought I'd lost it twice.


TOP RING PLATE par LensMagnet, on ipernity


Barrel


BARREL par LensMagnet, on ipernity


Loosened rings


RINGS par LensMagnet, on ipernity
08-07-2013, 01:08 AM   #10
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
You can see in the last shot that there is a bit of play in the aperture ring and the indicator ring, but I can't pull them over the top due to the auto/man switch.
I think if I could remove the focus ring, the indicator ring would be removable - but I can't figure that out.
Looking inside the barrel, it isn't clear what to loosen to achieve my aims easiest.
08-07-2013, 06:04 AM   #11
Junior Member




Join Date: Jul 2011
Location: Northern California
Posts: 27
From losing one in the field, I know the A-M switch is pressed on to a small flat stub that goes inside the lens, if that helps. Your lens is somewhat later than mine so your switch is larger and a slightly different shape. I don't know how to take the switch off without damage, the plastic is probably brittle after all these years.
09-09-2013, 02:00 PM   #12
Inactive Account




Join Date: Jul 2013
Posts: 18
Original Poster
And I'm still no further forward with this.
Not sure what to do next...
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!
bash, bit, focus, issue, 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
Mamiya / Sekor SX 55mm f/1.8 BKSPicture Lens Sample Photo Archive 0 02-02-2013 04:20 PM
Mamiya DTL 55mm/1.4 Opinions , Compatabillity Issue? seacapt Pentax SLR Lens Discussion 7 01-08-2010 11:29 AM
Mamiya / Sekor 55mm f1.8 or SMC Takumar 55mm f1.8? -kb- Pentax SLR Lens Discussion 14 09-16-2009 05:54 AM
Fuji Fujinon 1:1.8 55mm vs. Super-Multi-Coated Takumar 1:1.8 55mm carpents Pentax SLR Lens Discussion 6 06-27-2007 05:25 PM



All times are GMT -7. The time now is 03:52 PM. | 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