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Swappo
Joined: 02 Apr 2009
Posts: 327
Location: Sweden
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 Posted: Fri May 08, 2009 8:19 pm Post subject: Voigtländer 90mm and 75mm has uneven aperture blades? |
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Swappo wrote:
I recently bought a Voigtländer 75 Color Helios from ebay and when i got it i noticed that the aperture ring was not quite even.
I've noticed this phenomen in one other lens, and that is the russian Zenitar 16mm. While the Zenitar might be a nice lens, I'm not expecting it to be top notch quality... But with the Voigtländer I expect the best. 
Anyway, I mailed the seller and asked about this, and he said that it's a common problem with Voigtländer 75mm and 90mm.
I've tried to google this, but I can't seem to find any information about this thing. Anyone know anything about it? See pics.
And while speking of aperture of this lens... It's in OM mount and despite it has aperture 22 at the ring and ability to choose that, the ring doesn't get smaller than f/16. The seller also claimed that this was fully normal on OM lenses... True? |
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no-X
Joined: 19 Jul 2008
Posts: 2495
Location: Budejky, Czech Republic
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| Posted: Fri May 08, 2009 8:28 pm Post subject: |
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no-X wrote:
My V. 125/2.5 hasn't perfectly round aperture, too. But it doesn't affect anything and I think it's probably normal.
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Swappo
Joined: 02 Apr 2009
Posts: 327
Location: Sweden
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| Posted: Fri May 08, 2009 8:36 pm Post subject: |
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Swappo wrote:
| no-X wrote: |
| My V. 125/2.5 hasn't perfectly round aperture, too. But it doesn't affect anything and I think it's probably normal. |
Well, I had to check my 125/2.5 now, and it looked nice att bigger openings, but when stepped down to about half or more, I started to see that the ring wasn't quite even anymore... And at f22 it looked a bit lika a rain drop.  |
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scsambrook
Joined: 29 Mar 2009
Posts: 2167
Location: Glasgow Scotland
Expire: 2011-11-18
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| Posted: Fri May 08, 2009 10:07 pm Post subject: Aperture shape |
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scsambrook wrote:
Many auto-diaphragm lenses show this uneven shape at smaller apertures, but it has no effect on their performance unless the area of the opening varies from the halving/doubling sequence as the f number setting is changed. That seems to be rare, even in the least expensive lenses and most mis-shapen diaphragms. I'm no technician but do recall being told years ago that this irregular shape was connected with the way blades needed to move when being actuated by the camera - maybe somebody here can comment on that.
My C-V 35/1.7 Ultron rangefinder lens has the most beautifully shaped iris opening you could imagine, so clearly Mr Cosina is able to produce symmetrical apertures ...
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Stephen
Equipment: Pentax DSLR for casual shooting, Lumix G1 and Fuji XE-1 for playing with old lenses, and Leica M8 because I still like the optical rangefinder system. |
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F16SUNSHINE
Joined: 20 Aug 2007
Posts: 5486
Location: Left Coast
Expire: 2011-11-18
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| Posted: Fri May 08, 2009 10:12 pm Post subject: |
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F16SUNSHINE wrote:
It's common with many lenses. Even dare I say it.........Leica 
Not a problem unless very dramatic shape.
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Orio
Joined: 24 Feb 2007
Posts: 29545
Location: West Emilia
Expire: 2012-12-04
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| Posted: Fri May 08, 2009 10:16 pm Post subject: |
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Orio wrote:
Better an irregular shape (irregular is the norm in natural shapes) than a perfectly regular hexagon that speaks loud "hey I am a lens diaphragm" in every photo they appear in.
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Orio, Administrator
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Swappo
Joined: 02 Apr 2009
Posts: 327
Location: Sweden
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| Posted: Sat May 09, 2009 7:13 am Post subject: |
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Swappo wrote:
Thanks for answers everyone...
And Orio, I think you got a point there.
Anyone know anything about the other thing, that Voigtländer lenses in OM mount doesn't step down to f22? |
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