Canon 24-70L aperture blades

Hi,

 

I've just received my 24-70L and I have a question regarding the number of

aperture blades and their shape. The Digital Picture website says that this lens

contains 8 aperture blades for a round Bokeh.

 

My sample is not perfectly circular when I press the DOF preview button. I find

this a bit irritating, considering the lens is over 1000CAD.

 

Did anyone else recognize this, or do I have a bad sample. (Hexagonal apertures

suck)

 

Thanks.

 

Radu D.

8 blades should make octagons... right?

<p>This lens has Canon's circular aperture design; the edges of the blades are curved so that they approximate a circle rather than an octagon. But keep in mind that it's approximately circular, not absolutely truly perfectly circular. And also remember that Canon only claims that it remains "more rounded" for two stops down from wide open.</p>

Mine is perfectly round to within my measurement tolerance. Your lens is obviously faulty and will take second rate images. I heard a rumour that when they are made, the 24-70 lenses go through an aperture cirularity check to check the aperture is circular, but that recently, Canon have canned this testing phase to boost profits. So the little workers at Canon, knowing that their work won't be checked, assemble the lenses with sub optimal aperture circularity. They can do this much faster, and since they get paid per unit, they end up with much more cash to take home and spend on their nikon gear.

 

Actually, I was glad to hear that, because I've been taking some great photos with my lens and was worried that there was nothing wrong with it and that I had not got a bad sample like everyone else.

Yeah,

 

Sorry. Hectagon.

 

CI P: When you say perfectly round, do you actually mean a perfect circle without any single deformation? If you do, then my sample has a problem.

 

But, my blades are not perfectly circular, but are in the limits of what Steve said. So I'm not sure.

 

Very dissapointing though.

 

Thanks again.

CI P is taking a piss, your lens is working as designed. There are no lenses I'm aware of that can forma circular aperture at small aperture settings, they can only approximate it for the first couple stops. That's what Canon is talking about in their marketing literature.

 

Regardless, worry about something else. It's no big deal, and there's no other lens you can buy that will be substatially different. Go out and take some pictures.

Thanks Andy.

 

I love my lens anyway. Just wanting some clarification. But you are right.

 

Cheers,

 

Radu D.

Mine must only have four blades, because when I view photos i have taken with it, the photo's come out in a rectangular shape.

Perhaps I should have said my tolerance for roundness is quite big. If you think about it, it is impossible to make an 8 bladed aperture which is perfectly round. I think an old fuji compact I had had a choice of apertures which consisted of pieces of metal with different sized holes, which were placed in front of the sensor.

 

As an aside, I also heard that the canon elves save on razor costs by using reject aperture blades for shaving purposes.

Just for clarification:

 

Here is Canon statement.

 

Dear Radu Diaconu:

 

Thank you for your inquiry on the EF 24-70/2.8L USM lens. We value you

as a Canon customer and appreciate the opportunity to assist you.

 

The lens does not have a perfectly circular aperture. Please note, the

lens will have a relatively circular aperture within 2 stops from wide

open (down to f/5.6). At f-stops lower than f/5.6, the aperture will

become progressively more octagonal.

Hectagon? ...that's 100 edges, not 8.

wow,

 

Octagon, not Hexagon. Really making a fool of myself.

 

Sorry.