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06-22-2012, 10:02 AM   #1
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Sigma 8-16mm - excess fringing or par for the course?

So I just got a Sigma 8-16mm and I'm wondering if this kind of fringing is standard on this lens or if I should send it to Sigma for a once-over. I'm also wondering about corner softness, but that may just be my inexperience; this is my first wide angle lens. I understand they are a little rougher in the corners and more susceptible to fringing but this seems worse than what I've seen elsewhere. Can any other 8-16mm owners take a look and see if this needs fixed? Both shot on the K-7.

Thanks for the help!

I know the focus is off in this, I'm really just looking at the fringing here.


And the obligitory brick wall shot - note the black on white plastic nub in the bottom left corner which has come out more blue-grey.


Full sized versions can be viewed/downloaded here. More examples can be supplied if needed

06-22-2012, 10:27 AM   #2
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OMG....I once owned this lens...I do not remember it is this serious
and if the focus is right..the corner is ok even at wide open

Last edited by liukaitc; 06-22-2012 at 10:58 AM.
06-22-2012, 10:32 AM   #3
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I don't know anything helpful about that lens in particular. Generally speaking, two things really intensify CA/fringing. High contrast edges, and out of focus edges. Taken together, like in flowers on the extreme left and right, above, it's going to be pretty common. It may be the case that with a lens that wide, the effect is even more pronounced when it happens, but that's idle speculation.
06-22-2012, 10:42 AM   #4
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Sigma 8-16 experience

Hi,

many gretings from Germany. I have this lens since a couple of months. This strong kind of fringing I've never seen. There must be something odd with your lens.
Yes the cornes are soft and in several tests it is an issue mentioned everywhere.
But if you take an aperture below 7 it is fine.
I try to add a photo which I made with the lens and a K5. But the photo is in RAW format so I pushed it through Photoshop elements without big adjustments.
If you want to see the adjusted photo I can send it also but it is biiiiiig

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06-22-2012, 11:29 AM   #5
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Send it in for service, this is not normal. This lens with its fld glass has the best ca control out of any uwa lens on the market, there is definitely an issue with that copy...
06-22-2012, 11:38 AM   #6
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Fringing seems to be an elusive beast. I've taken nearly identical shots from the same lens and some have strong fringing and some don't. Although wide-aperture, high-contrast and focus are variables, there seems to be another component I can't nail down -- the direction of the light itself I think, or side-lighting if I am not using a hood maybe. I've been meaning to do some experiments with a polarizer to see what effect it has.
06-22-2012, 12:06 PM   #7
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Make images that are properly focused at a greater distance [the 8-16 is not a macro lens] before deciding if the fringing is excessive.
06-22-2012, 03:36 PM   #8
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Thanks for the replies, everyone.

I took several of the flowers and most of them had this kind of effect to some degree, even up through f/8.

Here's another better focused:


You can still see that the middle and edge flowers are fringing a bit. The out of focus areas are definitely worse, however.

I know it's not a macro lens, but if I can't get up close to things then what's the point?

Can anyone suggest a better test subject?

06-23-2012, 05:21 AM   #9
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I agree with joe.penn and suggest to send the lens to service. Of course you can do some additional tests like dead branches against the white sky or a dark fence in front of a white wall. But what you do you never get faith in the lens. If the service says it's ok (what I don't believe) you can get rid of it. If the service fixes the issue you'll be glad and it spares nerves. I had some experience with front/back-focus and Tamron lenses. https://www.pentaxforums.com/forums/images/smilies/mad.png
06-24-2012, 03:53 AM   #10
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I'll try and get out this afternoon and take a variety of pictures once the rain stops here in sunny England

Thanks again
06-24-2012, 12:56 PM   #11
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Ok, I had a chance to go out and take some pictures today. Oddly, the first few I took weren't even close to being in focus, even though the focus confirmation light was on. Also discovered it has some very interesting flare. And, of course, there's the fringing. Thoughts?

Fringing.


Unusual flare.


That's probably one of the better pictures from the day, minus the flare. Most of them seemed to be muddy or soft, even at f/8. That one's at f/11 - note the points on the sun.

Again, full size images are here and thanks again for everyone's input
06-24-2012, 06:36 PM   #12
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QuoteOriginally posted by vonBaloney Quote
..... I've been meaning to do some experiments with a polarizer to see what effect it has.
Good luck with that

Pete
06-24-2012, 06:47 PM   #13
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Based on the later images, I think the fringing is excessive. I seldom notice any with mine. The ghosting with the sun in the frame is typical.
06-25-2012, 02:46 PM   #14
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Well, I've packed it up and sent it back to the store, they're going to check it and send it on to Sigma. I'm now debating whether or not to keep it either way - I'm not sure I'm cut out for angles this wide. Anyhow, thanks again for everyone's input!

So it's not all doom and gloom for this lens, here's a shot I thought actually turned out rather well - including the spectacular flare. And of course, fringing mushrooms.

06-25-2012, 03:00 PM   #15
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QuoteOriginally posted by BentlyTCow Quote
Well, I've packed it up and sent it back to the store, they're going to check it and send it on to Sigma. I'm now debating whether or not to keep it either way
It takes quite a bit of shooting to get acquainted with UWA shooting - I would give it some time once the lens comes back, UWA lenses help photographers to make incredible photographs. If you need inspiration, check out this thread:

https://www.pentaxforums.com/forums/lens-clubs/107938-sigma-8-16mm-club.html

Good luck with your UWA endeavors...
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