Voigtländer 90mm and 75mm has uneven aperture blades?

Swappo · Joined: 02 Apr 2009 Posts: 327 Location: Sweden

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. Smile

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?

no-X · Posted: Fri May 08, 2009 8:28 pm Post subject:

My V. 125/2.5 hasn't perfectly round aperture, too. But it doesn't affect anything and I think it's probably normal.

Swappo · Joined: 02 Apr 2009 Posts: 327 Location: Sweden

scsambrook · Expire: 2011-11-18

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 ...

F16SUNSHINE · Expire: 2011-11-18

It's common with many lenses. Even dare I say it.........Leica Surprised

Not a problem unless very dramatic shape.

Orio · Expire: 2012-12-04

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.

Swappo · Joined: 02 Apr 2009 Posts: 327 Location: Sweden

Thanks for answers everyone...
And Orio, I think you got a point there. Smile

Anyone know anything about the other thing, that Voigtländer lenses in OM mount doesn't step down to f22?