[SSGGeezer]

This is an image of my new (used) Sigma 30mm f/1.4 DC (Not Art) From the rear. I was taking shots of all my lenses both for insurance records and for practice using a flash when I noticed how poorly shaped the octagon formed by the lens was. I realize that as it closes down to a smaller aperture, that it may not always form a perfect shape but looking with my eyes it is even worse than how it appears in the picture.
The lens takes very nice images but now I am concerned. It is in warrantee from the seller but that is a pain in the rear to deal with.

Any advice is appreciated. Thanks.

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[ramseybuckeye]

I can't imagine that is not going to get worse. blades must be loose or sticky.

[thazooo]

I have a Tokina that does that. It changes as you mentioned and will sometimes be normal. It will on occasion effect image quality, kinda like diffraction.

[SSGGeezer]

I have a Tokina that does that. It changes as you mentioned and will sometimes be normal. It will on occasion effect image quality, kinda like diffraction.

The images so far have been very good and it acts as any of my screw drive lenses do when focusing. The only time it seems to delay shutter activation is when it has not focused or is having issues in low light.
I also have a 6 month warrantee from the merchant where I purchased it so I think I will do some more testing and checking here for other's experiences with similar issues before deciding.
Thanks for the comment.

[Unregistered User 8]

Should I keep this?

Hi Thomas, I don't believe this is an issue to worry about as most apertures are not symmetrical. The only time that you might notice the shape is when photographing lights ( Christmas lights, street lights etc ) at night, and find that the bokeh is not symmetrical. I just checked my lenses, and even my Sigma 35 1.4 ART ( 9 rounded blades ) is not a perfect shape. Do lots of testing, take lots of different types of shots over the next 5 months, and enjoy your lens. That still gives you 1 month to send it back if you are not happy. Good luck.

[SSGGeezer]

Thanks, I do love the IQ of it so far! And I have spent more money ordering a hood and front lens cap already.

[Unregistered User 8]

Thanks, I do love the IQ of it so far! And I have spent more money ordering a hood and front lens cap already.

Enjoy your " new toy."

[zjacreman]

I've got lenses that look like they've been repeatedly drop-kicked over their long, hard lives and their apertures don't look like that. It looks off-center, too? No way I'd keep it.

[SSGGeezer]

I just was playing with it in TAV mode and it looks less strange after use again. It takes very nice images.

[Alex645]

as it closes down to a smaller aperture, that it may not always form a perfect shape but looking with my eyes it is even worse than how it appears in the picture.
The lens takes very nice images but now I am concerned. It is in warrantee from the seller but that is a pain in the rear to deal with.

It is definitely grease sticking on some of the aperture blades which need cleaning. If you shoot wide open, itʻs no big deal, but starting around f/4, you will get over exposures and some wonky diffraction and less depth of field....plus oddly shaped bokeh.

I would send it back because although it sometimes will not be an issue, it will probably only get worse. Once it is out of warranty, itʻs going to cost nearly $200 to get that fixed. If you love the lens, and the seller is KEH, ask them if they can fix it. In other words, you donʻt want it refunded....just fixed. I think theyʻd be more likely to help you with that now, than closer to the 6 month warranty end.

[dms]

I have a lens that does it, and it seems to be the same shape at all f-stops, and instantly stops down, which suggests to me it is not grease--and that may be yours also. I would think the effect may be noticeable shooting small (or distant) lights at night, where they are out of focus (as pjv noted above), and likely not in usual situations.

[BigMackCam]

Several of my very well made Soviet lenses from the 80s have diaphragms that are consistently or randomly non-symmetrical. It's fairly common on those models, and caused by rather loose tolerances in the diaphragm mechanism and components. I've also noted the effect on a couple of fairly recent brand new Tamron lenses.

You might just be able to see the uneven shape in out-of-focus highlights (blurred Christmas lights, for example) with the aperture stopped down a little, but it's one of those things you'd really have to look for.

If the lens gives nice results and you're otherwise happy, I wouldn't worry about it. If it's going to eat at you, though, send it back. There's no sense hanging onto a lens you'll be worrying about.

[SSGGeezer]

Going to return it even though I bough new filters and a hood for it. Erratic focus and when it is somewhat consistent, it is extremely front focused. Thanks for all the advice though, I appreciate it.

[BigMackCam]

Going to return it even though I bough new filters and a hood for it. Erratic focus and when it is somewhat consistent, it is extremely front focused. Thanks for all the advice though, I appreciate it.

If you're not completely satisfied, you're doing the right thing