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tianqiang0316
Joined: 27 Feb 2012
Posts: 10
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 Posted: Mon Feb 27, 2012 5:31 am Post subject: How to repair the aperture of Meyer oreston 50 1.8 |
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tianqiang0316 wrote:
I am a fresh man, recently I bought a lens named meyer oreston 50 1.8 from ebay. But there's some problems.
The aperture can only be used at 1.8 stop.
Would you pls teach me how the disassemble and repaire it ? I 've nemer repaired lens before.
Thanks a lot and best regards,
Fox.
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Spotmatic
Joined: 18 Aug 2008
Posts: 4045
Location: Netherlands
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| Posted: Mon Feb 27, 2012 7:35 am Post subject: |
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Spotmatic wrote:
Have you never repaired a lens before? Then consider this lens as a loss and a learning subject. You'll have to start somewhere and this Oreston may just be it... 
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Pentax K-5 + Pentax 645 + Canon 5D + Bessa RF 10,5cm Heliar, and a 'little' bag full of MF lenses. The lens list is * here *.
My fast 80s: Asahi-Kogaku Takumar 83mm f/1.9 - Super-Takumar 85mm f/1.9 - FA 77mm f/1.8 Limited - Cyclop 85/1.5 (Helios-40 innards) - Komura 80mm f/1.8 - Meyer Görlitz Primoplan 7,5cm 1:1.9 - Carl Zeiss Jena 80mm f/1.8 Pancolar - Canon 85mm f/1.8 S.S.C. - Canon 85mm f/1.2 S.S.C. Aspherical |
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Excalibur
Joined: 19 Jul 2009
Posts: 5017
Location: UK
Expire: 2014-04-21
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| Posted: Mon Feb 27, 2012 8:08 am Post subject: Re: How to repair the aperture of Meyer oreston 50 1.8 |
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Excalibur wrote:
| tianqiang0316 wrote: |
I am a fresh man, recently I bought a lens named meyer oreston 50 1.8 from ebay. But there's some problems.
The aperture can only be used at 1.8 stop.
Would you pls teach me how the disassemble and repaire it ? I 've nemer repaired lens before.
Thanks a lot and best regards,
Fox.
[/b] |
Could be the blades stuck:- try stopping the lens down to f22 and press pin in (at the back) for stop down mode...and then hold the lens in one hand and bang the lens with your palm of your other hand, this might free the blades if slightly stuck because of non use.
_________________
Canon A1, AV1, T70 & T90, EOS 300 and EOS300v, Chinon CE and CP-7M. Contax 139, Fuji STX-2, Konica Autoreflex TC, FS-1, FT-1, Minolta X-700, X-300, XD-11, SRT101b, Nikon EM, FM, F4, F90X, Olympus OM2, Pentax S3, Spotmatic, Pentax ME super, Praktica TL 5B, & BC1, , Ricoh KR10super, Yashica T5D, Bronica Etrs, Mamiya RB67 pro AND drum roll:- a Sony Nex 3
.........past gear Tele Rolleiflex and Rollei SL66.
Many lenses from good to excellent. |
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tianqiang0316
Joined: 27 Feb 2012
Posts: 10
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| Posted: Mon Feb 27, 2012 1:00 pm Post subject: Re: How to repair the aperture of Meyer oreston 50 1.8 |
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tianqiang0316 wrote:
| Excalibur wrote: |
| tianqiang0316 wrote: |
I am a fresh man, recently I bought a lens named meyer oreston 50 1.8 from ebay. But there's some problems.
The aperture can only be used at 1.8 stop.
Would you pls teach me how the disassemble and repaire it ? I 've nemer repaired lens before.
Thanks a lot and best regards,
Fox.
[/b] |
Could be the blades stuck:- try stopping the lens down to f22 and press pin in (at the back) for stop down mode...and then hold the lens in one hand and bang the lens with your palm of your other hand, this might free the blades if slightly stuck because of non use. |
Many thanks of your kindly reply.
BUt I have do it. Both the pin and epth of field preview button do not work. |
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tianqiang0316
Joined: 27 Feb 2012
Posts: 10
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| Posted: Mon Feb 27, 2012 1:02 pm Post subject: |
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tianqiang0316 wrote:
| Spotmatic wrote: |
| Have you never repaired a lens before? Then consider this lens as a loss and a learning subject. You'll have to start somewhere and this Oreston may just be it... |
I have decided!  |
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tomzcafe
Joined: 01 Jun 2009
Posts: 196
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| Posted: Mon Feb 27, 2012 1:25 pm Post subject: |
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tomzcafe wrote:
the should be a button at the side of the ring which you need to press to close the aperture, as what I did with my Meyer Oreston 50/1.8.
you may open up the lens from the bottom to see how the aperture closing from the side button works; which I did it after I bought the lens last time.
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tianqiang0316
Joined: 27 Feb 2012
Posts: 10
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| Posted: Mon Feb 27, 2012 1:58 pm Post subject: |
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tianqiang0316 wrote:
| tomzcafe wrote: |
the should be a button at the side of the ring which you need to press to close the aperture, as what I did with my Meyer Oreston 50/1.8.
you may open up the lens from the bottom to see how the aperture closing from the side button works; which I did it after I bought the lens last time. |
The close button doesn't work. |
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Excalibur
Joined: 19 Jul 2009
Posts: 5017
Location: UK
Expire: 2014-04-21
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| Posted: Mon Feb 27, 2012 5:45 pm Post subject: Re: How to repair the aperture of Meyer oreston 50 1.8 |
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Excalibur wrote:
| tianqiang0316 wrote: |
| Excalibur wrote: |
| tianqiang0316 wrote: |
I am a fresh man, recently I bought a lens named meyer oreston 50 1.8 from ebay. But there's some problems.
The aperture can only be used at 1.8 stop.
Would you pls teach me how the disassemble and repaire it ? I 've nemer repaired lens before.
Thanks a lot and best regards,
Fox.
[/b] |
Could be the blades stuck:- try stopping the lens down to f22 and press pin in (at the back) for stop down mode...and then hold the lens in one hand and bang the lens with your palm of your other hand, this might free the blades if slightly stuck because of non use. |
Many thanks of your kindly reply.
BUt I have do it. Both the pin and epth of field preview button do not work. |
erm well that's because the blades are stuck wide open  When you press the pin or lever in, it's set to close the blades and giving the lens a gentle bang will give it added help to close at f22. Believe me what I've said works (from experience) if the blades are very slightly stuck as mentioned above.
_________________
Canon A1, AV1, T70 & T90, EOS 300 and EOS300v, Chinon CE and CP-7M. Contax 139, Fuji STX-2, Konica Autoreflex TC, FS-1, FT-1, Minolta X-700, X-300, XD-11, SRT101b, Nikon EM, FM, F4, F90X, Olympus OM2, Pentax S3, Spotmatic, Pentax ME super, Praktica TL 5B, & BC1, , Ricoh KR10super, Yashica T5D, Bronica Etrs, Mamiya RB67 pro AND drum roll:- a Sony Nex 3
.........past gear Tele Rolleiflex and Rollei SL66.
Many lenses from good to excellent. |
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peterqd
Joined: 28 Feb 2007
Posts: 7448
Location: near High Wycombe, UK
Expire: 2014-01-04
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| Posted: Mon Feb 27, 2012 7:05 pm Post subject: |
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peterqd wrote:
I don't know of any repair instructions for this lens. I once adjusted the infinity focus on one, which was very straightforward.
You will need to clean the aperture blades with a cotton wool bud and plenty of petrol lighter fluid, and keep moving the blades until the fluid dries. You can probably access them by removing the mount end of the lens and removing the rear lens group, which is probably fixed with 3 small grub screws. Be carful not to lose the small ball bearing under the aperture ring, which is spring-loaded and jumps out.
If you need to go further and dismantle the diaphragm, the CZJ 2.8/50 Tessar might be quite similar design to the Oreston. Here are the instructions for the Tessar:
http://oomz.net/tessar/
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Lloydy
Joined: 02 Sep 2009
Posts: 7788
Location: Ironbridge. UK.
Expire: 2022-01-01
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| Posted: Mon Feb 27, 2012 8:23 pm Post subject: |
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Lloydy wrote:
Wonderful ! I've got a Tessar in bits that I took apart years ago and couldn't get back together. 
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tianqiang0316
Joined: 27 Feb 2012
Posts: 10
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| Posted: Tue Feb 28, 2012 7:36 am Post subject: |
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tianqiang0316 wrote:
| peterqd wrote: |
I don't know of any repair instructions for this lens. I once adjusted the infinity focus on one, which was very straightforward.
You will need to clean the aperture blades with a cotton wool bud and plenty of petrol lighter fluid, and keep moving the blades until the fluid dries. You can probably access them by removing the mount end of the lens and removing the rear lens group, which is probably fixed with 3 small grub screws. Be carful not to lose the small ball bearing under the aperture ring, which is spring-loaded and jumps out.
If you need to go further and dismantle the diaphragm, the CZJ 2.8/50 Tessar might be quite similar design to the Oreston. Here are the instructions for the Tessar:
http://oomz.net/tessar/ |
Thansk a lot!
But I have heard that dismandle the rear lens might change the optical axis, is it true? |
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