View Full Version : Comments welcome on an errant shutter blade

duff photographer
8-Feb-2008, 16:23
I recently bought a Schneider 180mm Apo-Symmar L (new). After a while I noticed that one of the shutter blades was out of sync with the rest. In other words it appeared slightly more open than the rest. The result is that, when progressively stopped down, the shutter opening looks slightly tear-drop shape.

The lens went back to Schneider and then to Copal. Both said that the shutter was within tolerable limits and would not affect picture quality, e.g., bokeh.

I have no reason to doubt their word but I would like to know if a non-round shutter opening would affect the final photograph in any way.

Many thanks.


8-Feb-2008, 16:33
Yer talking about aperture blades and aperture shape, not shutter blades... right?

Peter K
8-Feb-2008, 16:59
A shutter like a Copal never opens like an aperture but in star shape. But the time needed to open or close a shutter is always short compared with the exposure time. So it wouldn't affect the picture in any way.

Peter K

duff photographer
10-Feb-2008, 10:15
Yer talking about aperture blades and aperture shape, not shutter blades... right?

Sorry for the misinformation. Yes - I meant aperture blades not shutter.

(and my apologies to Peter K as well!)

Peter K
10-Feb-2008, 10:30
Depend on the number of aperture blades the aperture is more or less circular. E.g. the aperture of a Copal Press No. 1 is a hexagon and the aperture of a Copal 3 has 10 corners. But this doesn't influence the performance at all. Special lenses as soft focus lenses need a more circular diaphragm because this lenses uses spherical aberration for the "bokeh".

Can you show a picture or two of the diaphragm to us?

Peter K

duff photographer
12-Feb-2008, 08:25
Hello Peter,

Sorry for the delay. I have attached a photo of the aperture. As you can see there is not much difference wide open and it would not affect image quality. However, as one stops down, it progressively gets 'worse'; although I can't imagine using f64.


Ole Tjugen
12-Feb-2008, 08:55
That's not bad at all. Live with it - that's the best advice I can give you.

Peter K
12-Feb-2008, 09:14

take some pictures with different f-stops and you will see there is no reason to think about the diaphragm.

Also you can measure the transmission of the lens with an TTL exposure meter at different f-stops to dispel your doubts.

Peter K

duff photographer
12-Feb-2008, 16:05
Many thanks Peter and Ole. I shan't worry about it (but I know it will affect the resale value if I ever get rid of it - ah well). Any doubts have been put to rest. Cheers.


13-Feb-2008, 20:54
Looks like normal variation to me. I think that when examined closely, most of my lenses have some asymmetry at small apertures.

14-Feb-2008, 00:37
I've never really looked at my lens apertures that closely but I've never noticed an asymmetry as prominent as that. If you bought it new and it's covered you could try to get it replaced just so you'll feel better about it, or at the very least not have to worry about it haunting you if you sell it someday. Though to be honest, I'm not sure it's significant enough that I'd have noticed it if you hadn't mentioned it.

I doubt it'll affect much anyway, in most scenarios if you're stopping down that much you won't have out of focus points to worry about the shape of anyway.

Anxiety about this kind of thing is the reason I don't obsessively examine my gear anymore. It's easier on the sanity to only pull out the microscope if the final images are suffering somehow.

domenico Foschi
14-Feb-2008, 00:49
Don't worry the images will look fine.
I have been dealing lately with a really bad asymmetry in my Heliar lens at the point that thought that I should have decrease the exposure somewhat.
The imags where fine.
The bad news is that I tried to fix it myself by opening the shutter and.... well now the leaves are all sparse in a box and are haunting me at night, rattling, just when I reach REM stage.

duff photographer
14-Feb-2008, 15:34
Thanks again all.