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Sigma 16mm 1.4 - focus problems at 2.8 and 5.6 in AF-S
- Thread starter CyeJoeBob
- Start date
trenzterra
Leading Member
So far, I can reproduce the issue at f/2.8 with consistency, using an ISO camera test chart. I will bring that down to Sigma Singapore. I guess the problem with EVF is easiest to prove. With Live View, it happens only when Focus Priority is set to Release. Not sure if Sigma will then fault me saying that the camera might not have acquired focus when set to FP Release.
At f/5.6, the issue isn't apparent in test charts and the problem doesn't manifest very often. It's only apparent at further distances. Not sure how I can prove it.
On a related note, seems like the kit PZ 16-50mm lens has issues focusing at 50mm too, but this time, only at AF-C. What a wild world we live in...
At f/5.6, the issue isn't apparent in test charts and the problem doesn't manifest very often. It's only apparent at further distances. Not sure how I can prove it.
On a related note, seems like the kit PZ 16-50mm lens has issues focusing at 50mm too, but this time, only at AF-C. What a wild world we live in...
Mike_Italy
Well-known member
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Alway Balances emphasis.
About the slight oof when live view effect off i want to test again because i want to know if the oof is due tu the 2.8 issue or a focus shift issue generated by the af acquisition wide open(f1.4) and picture taken stopped down (f2.8).
The focus shift is a phenomena i known recently.
If the slight oof with live view effect off is present at all aperture then focus shift could be the reason instead of the f2.8 bug
I tested for focus shift - I focussed at f1.4 and then changed aperture to f2.8 without refocusing, and it was accurate. No visible focus shift.
Live View, F5.6, AF-S, priority “AF” I also see the issue near infinity.
Yep, best to take them outside (or take photo through a window of buildings at a distance), should be possible to replicate.
Sigma has already stated that it's a camera issue. I wonder how long it will take for Sony to fix it? In the meantime I'll continue to enjoy using the lenses in AF-C with no issues.
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Willy81
Forum Pro
I don't expect and would be totally be surprised if Sony ever addressed this issue.
I also understand the limits of this lens with my A6300 and enjoy using the combo.
zackiedawg
Forum Pro
You could always buy it from somewhere with a return policy, and find out if you happen to be one of those who doesn't experience the issue at all...in which case, you don't have to worry about any of the workaround stuff. If the issue DOES pop up, you can just return the lens.
I've not worked around a single way with my copy on my camera - I just stick the lens on, walk around, and shoot whatever I want, however I want - and I do it in all the ways that's supposed to be an issue - F2-F2.8, AF-S, using EVF, no DMF or focus magifier, Live view effects on, flex spot focus. It's pure point-and-shoot simple and accurate for me.
Maybe you'll find that you get one that doesn't seem to have the issue, or maybe you'll find that the issue never comes up in any of the ways you routinely like to shoot, making it a non-issue. And if not, you can always just ship it back for a refund. The lens is lovely and sharp, and so nice to have a wide angle fast prime!
snapa
Veteran Member
Great advise Justin, I think I'll give your suggestion a try. Maybe, just maybe, there are copies out there that simply do not have this issue, it is worth my time and effort to investigate that possibility. I do not have a WA lens, except for my 16-50. Also, as we all know at 16 mm (especially in lower light), the kit lens really does not do a good job at creating sharp, low noise images. I know from experience my kit lens doesn't, because I've tried.
Using a flash indoors does help by bringing down the ISO, which does give me better/sharper pictures, but of course using a flash is not practical in all situations.
BTW, if the issue only happens <1% of the time, at least using DMF with focus magnifier seems like something I'd probably be able to deal with.
paul wassermann
Senior Member
My lens does miss focus 2.0, to 2.4. I put a little sticker on my lens hood reminding me to possibly use continuous focus. I absolutely love the lens and can shoot CF as needed without much inconvenience.
mooreimaging
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I've been hearing I've been hearing a lot about the problems on this lens but from my perspective my lens does not seem to have any issues and I can auto focus every single time.
CyeJoeBob
Active member
It's clearly visible at the edges, but the centre is often only very slightly out of focus so that you have to look twice, even at 100%. The field curvature seems to make it worse towards the edges.
See: https://www.dpreview.com/forums/post/60988371
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CyeJoeBob
Active member
Yeah, that's the reason I'm a bit confused.
I bought a used Sigma 16mm in mint condition on Ebay now. And unsurprisingly it has exactly the same focus problems. The problems are not just similar, they are exactly the same, at the same aperture values. I bought all three samples, of the lens, which I tested, from different retailers and they have almost exactly the same issues.
I think it's a matter settings and photographic habits why many don't see any problems.
I bought a used Sigma 16mm in mint condition on Ebay now. And unsurprisingly it has exactly the same focus problems. The problems are not just similar, they are exactly the same, at the same aperture values. I bought all three samples, of the lens, which I tested, from different retailers and they have almost exactly the same issues.
I think it's a matter settings and photographic habits why many don't see any problems.
paul wassermann
Senior Member
Agree, if you are setting continuous focus or live view display effect "off" you will not see any problem. Or if you never shoot between 1.7 and 2.5
It remains one of my all time favorite lenses.
trenzterra
Leading Member
Live view display effect off does not solve the problem at further distances (at least on PAL, not sure about NTSC)
Mike_Italy
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I also verified that live view off improve but not resolve the problem. Afc or afs with focus magnifier seems instead the right workaround
zackiedawg
Forum Pro
Unfortunately, the problem is even more mysterious than that, because there are still some of us who aren't seeing the issue despite using exactly the settings that supposedly cause the problem to always occur. It's part of why we're trying all kinds of other settings within the camera, like the focus priority setting, to try to figure out which might be different between all those who do not have the issue and all those who do. I have live view effects on, AF-S, and shoot almost exclusively between F1.4 and F2.8 with this lens, and have never seen the issue on my A6300. Trying to test if 'balanced emphasis vs release vs focus could have anything to do with it, but so far in early tests, that hasn't changed the behavior on mine (other than 'release' which if I press the shutter quickly will allow me to fire an unfocused shot, but then that's the purpose of that setting!). As long as I'm half-pressing and waiting for a focus confirm, then shooting, the focus is still coming out accurate and on-target with flex spot medium setting. I May still try a few more tests this afternoon to see if I can make this issue occur.
trenzterra
Leading Member
Hi all,
I was supposed to head down to Sigma's Singapore office last week but was unable to do so due to an emergency. This morning, I managed to speak with the rep (with whom I was previously in email contact with) over the phone.
Apparently, after I pointed them to this thread, they spent half a day trying to reproduce the issue on two samples of the 16mm lenses, albeit with a Sony A7ii and A7iii, but was unable to reproduce the issue. They are suspecting perhaps I did not align the focus points properly, or it could be a narrow DOF issue. He also mentioned that they have not received any complaints about this issue thus far, and from what he tells me, it does not seem that Sigma Japan is aware of this issue at all, contrary to what was represented by Sigma Germany.
In any case, I will try to make it down to their office next week or the following week, to point out the issue to them. Perhaps it only happens on the crop bodies and does not affect FF. Meanwhile, I have shot a video of me trying to reproduce the issue as well as some test shots and have forwarded it to them.
I was supposed to head down to Sigma's Singapore office last week but was unable to do so due to an emergency. This morning, I managed to speak with the rep (with whom I was previously in email contact with) over the phone.
Apparently, after I pointed them to this thread, they spent half a day trying to reproduce the issue on two samples of the 16mm lenses, albeit with a Sony A7ii and A7iii, but was unable to reproduce the issue. They are suspecting perhaps I did not align the focus points properly, or it could be a narrow DOF issue. He also mentioned that they have not received any complaints about this issue thus far, and from what he tells me, it does not seem that Sigma Japan is aware of this issue at all, contrary to what was represented by Sigma Germany.
In any case, I will try to make it down to their office next week or the following week, to point out the issue to them. Perhaps it only happens on the crop bodies and does not affect FF. Meanwhile, I have shot a video of me trying to reproduce the issue as well as some test shots and have forwarded it to them.
New Sigma 16 1.4, just tested with A6000 and Nex-7.
Same issue between 2.0 and 2.8, very easy to reproduce.
Can be worked around by using AF-C or, in low light, by using screen.
I'm in doubt whether to return the lens or keep it, as it is razor sharp.
///marco
Same issue between 2.0 and 2.8, very easy to reproduce.
Can be worked around by using AF-C or, in low light, by using screen.
I'm in doubt whether to return the lens or keep it, as it is razor sharp.
///marco
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