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GregS
Joined: 14 Aug 2009
Posts: 7
Location: Sydney
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 Posted: Wed Aug 19, 2009 11:41 am Post subject: What kind of damage this lens have? dose change shape !!! |
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GregS wrote:
This is a front group of Pentax M 50mm f/1.7 I wonder if can be repaired?
I don’t think it is fungus???? This “think” changing shape every time I move it to different position. Sorry for the quality of first photo.
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Spotmatic
Joined: 18 Aug 2008
Posts: 4045
Location: Netherlands
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| Posted: Wed Aug 19, 2009 11:46 am Post subject: |
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Spotmatic wrote:
Based on the optical diagram I think some residual oil from the helicoid has gotten behind the front element. This should clean easily. You'll need to unscrew the front part of the lens though (with tweezers).
Was the lens kept in a hot car?
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Peter - Moderator
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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GregS
Joined: 14 Aug 2009
Posts: 7
Location: Sydney
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| Posted: Wed Aug 19, 2009 12:18 pm Post subject: |
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GregS wrote:
| Spotmatic wrote: |
Based on the optical diagram I think some residual oil from the helicoid has gotten behind the front element. This should clean easily. You'll need to unscrew the front part of the lens though (with tweezers).
Was the lens kept in a hot car? |
This lens was a gift from a father-in-law..  …he he (thinking what to give him for next fathers day 
It was kept in a house unused for a very long time maybe 20 years or so, cosmetically looks very good. The storage place, unfortunately is in part of the house where the air-condition doesn’t reach, and the house is in a pretty hot country -Australia
I hope I can clean it, I will have go at it |
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hasan
Joined: 12 Mar 2007
Posts: 313
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| Posted: Wed Aug 19, 2009 12:20 pm Post subject: |
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hasan wrote:
I have a lens with almost same problem,
it seems the coating has kinda "peeled off"
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Pentax Z20 |Pentax K100D |SMC K35/3.5 |SMC K50/1.4 |SMC A50/1.4
|SMC K135/2.5 |SMC DA18-55 |SMC FA80-320 |AR 135/2.8(Chinon) |AR 55/1.4(M42)
|Sigma MF 90/2.8 |Sigma 28-80/3.5-5.6 |Exakta 24/2.8 |Vivitar 2x Macro Focusing TC |
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GregS
Joined: 14 Aug 2009
Posts: 7
Location: Sydney
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| Posted: Wed Aug 19, 2009 12:28 pm Post subject: |
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GregS wrote:
| hasan wrote: |
I have a lens with almost same problem,
it seems the coating has kinda "peeled off" |
To me looks like is same kind of fluid floating around, I think that Spotmatic is right at least in my case ??? |
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luisalegria
Joined: 07 Mar 2008
Posts: 6602
Location: San Francisco, USA
Expire: 2018-01-18
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| Posted: Wed Aug 19, 2009 4:29 pm Post subject: |
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luisalegria wrote:
There would likely be very little effect on image quality, no matter the cause, unless it gets a lot bigger.
It could also be separation of cemented elements.
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I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work. |
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hasan
Joined: 12 Mar 2007
Posts: 313
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| Posted: Thu Aug 20, 2009 2:41 am Post subject: |
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hasan wrote:
| GregS wrote: |
| hasan wrote: |
I have a lens with almost same problem,
it seems the coating has kinda "peeled off" |
To me looks like is same kind of fluid floating around, I think that Spotmatic is right at least in my case ??? |
Well, in my case luisalegria seems to be correct.
At least I couldn't detect any oil on mine.
_________________
Pentax Z20 |Pentax K100D |SMC K35/3.5 |SMC K50/1.4 |SMC A50/1.4
|SMC K135/2.5 |SMC DA18-55 |SMC FA80-320 |AR 135/2.8(Chinon) |AR 55/1.4(M42)
|Sigma MF 90/2.8 |Sigma 28-80/3.5-5.6 |Exakta 24/2.8 |Vivitar 2x Macro Focusing TC |
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Krisgage
Joined: 16 Mar 2009
Posts: 681
Location: Singapore
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| Posted: Mon Aug 24, 2009 7:36 pm Post subject: |
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Krisgage wrote:
it looks like oil to me. notice a faint "rainbow" or am I imagining things
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http://krisgage.livejournal.com |
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Séamuis
Joined: 20 Jul 2008
Posts: 157
Location: here & now
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| Posted: Mon Aug 24, 2009 8:03 pm Post subject: |
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Séamuis wrote:
I also agree with the 'oil' theory.
_________________
Fish-Eye -- Fish-Eye-Takumar 1:11/18
WideAngle -- Super-Takumar 1:3.5/28, Auto-Takumar 1:2.3/35, Auto-Takumar 1:3.5/35, Super-Takumar 1:3.5/35
Normal -- S-M-C Takumar 1:1.4/50, Auto-Takumar 1:1.8/55, Super-Takumar 1:1.8/55, S-M-C Takumar 1:1.8/55, SMC Takumar 1:1.8/55, Auto-Takumar 1:2/55
TeleType -- S-M-C Takumar 1:1.8/85, S-M-C Takumar 1:2.8/105, Super-Takumar 1:3.5/135, Tele-Takumar 1:6.3/300
Zoom -- Super Takumar-Zoom 1:4.5/70~150
Macro -- Macro-Takumar 1:4/50, S-M-C Macro-Takumar 1:4/100, Bellows-Takumar 1:4/100
Medium Format -- S-M-C Takumar 6X7 1:2.8/90 LS
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aoleg
Joined: 22 Feb 2008
Posts: 1387
Location: Berlin, DE
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| Posted: Mon Aug 24, 2009 8:55 pm Post subject: |
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aoleg wrote:
Either oil (easily repeirable) or coating separation (not repairable). If it's oil, the fix is simple: use a friction tool to unscrew front nameplate, then your fingers (rubber gloves would come handy) to unscrew the front lens element. Note that the entire front optical block might come off as you unscrew; that's OK, you'll be able to detach the front lens from it without messing with levers or aperture. I cleaned an extremely dusty 50/2 this way.
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