Canon 35/2.8 aperture doesn't open completely ...

[markloch]

Hi,

I just picked up a canon 35/2.8, chrome version, reads Canon, not Serenar.

I notice that when open @ 2.8 the blades are still visible, maybe a couple of millimeters still exposed (darker inner ring in photo). I'm wondering if this is normal for this lens. On the other hand I see another ring forward of the blades also obscuring the edges of the lens (lighter, outer ring in photo) and it otherwise seems to stop down normally, and when opening from 4 to 2.8 the blades appear to open evenly, not like they're hesitating, nor does it feel like it's binding or anything.

I'm hoping someone can check their lens. I've got a 3-day return privilege I'll take advantage of it if need be.

Thanks!
Mark

 

[markloch]

I just noticed that on the photo the seller provided, the lens is wide open ... and the aperture ring is turned PAST f/2.8 ...

 

[Sonnar Brian]

You can suspect that the lens was worked on and not properly re-assembled. The index mark for the F-stop is off somehow.

 

[markloch]

I think it's a build design/quality issue - with a little effort - more than one would typically apply - it can be rotated past 22 in one direction and past 2.8 in the other. By tweaking it past 22, and rotating it back to to f/2.8, it's fully open. This sort of resets it as it can't open any further, so 2.8 id 2.8 and 22 is 22. Conversely, rotating it past 2.8, then clicking in at 2.8 shows blades. In short, there's some slip that allows, uh, calibration with a not-so-gentle touch. Thereafter it's a matter of not ham-fisting the thing.