Strange lens effects


michaelblue

Link Posted 15/08/2017 - 13:45
Has anyone had this problem before........


...or this.....





...another example......


If you zoom in you'll see 'double image'
It looks like camera shake but it isn't, the lens is a Sigma 150-500mm, I'm getting this with 3 different cameras so I suspect the lens.
I've not done any tests but this seems to only appear at 300mm or longer

Any thoughts on this would be really appreciated
Regards,
Michael
My new website:link

JAK

Link Posted 15/08/2017 - 13:48
Are you using both optical and sensor shake reduction systems simultaneously?
John K

michaelblue

Link Posted 15/08/2017 - 14:15
JAK wrote:
Are you using both optical and sensor shake reduction systems simultaneously?

Niether, no shake reduction at all.
The first one was at 1/800th sec. 500mm, the second was at 1/800th sec. 440mm, the last one was 1/000th sec, 440mm. All were taken using a beanbag for support.
I've even had this while using a tripod and no 'shake reduction'

It seems to be more noticeable on slightly out of focus areas
Regards,
Michael
My new website:link
Last Edited by michaelblue on 15/08/2017 - 14:17

pschlute

Link Posted 15/08/2017 - 19:09
The first one looks like Nessie ?
Peter



My Flickr page

JAK

Link Posted 16/08/2017 - 00:29
If not an SR issue could it, perhaps have a loose or misaligned lens element in it? Given the problem has been narrowed down to the lens I'd ask Sigma the question. https://www.sigma-imaging-uk.com/support
A nuisance that happening. Suspect it might be emotional when you get the quote, but hope not!
I'd say give the lens a shake to see if it rattles, but given it has that optical SR that might be misleading.
Has the lens had the mount done? Could be an excuse to get that done and just mention the problem for them to check?? You never know, they may just sort it for you!
John K
Last Edited by JAK on 16/08/2017 - 00:49

sebas77

Link Posted 16/08/2017 - 08:53
do some tests, those areas could simply be out of focus. At that focal range, you can expect to be everything in focus. So if you were focusing something else (like it seems it is the case) it's normal.

pentaxian450

Link Posted 16/08/2017 - 12:18
It looks like shallow depth of field. If you could post the second picture full size, we could give you a better assumption. It looks like the central bird is on focus, but having it full size would really help with a definitive "verdict".
Yves (another one of those crazy Canucks)

JAK

Link Posted 16/08/2017 - 17:39
Looking again at these #1 could be subject movement causing the blurred edge to the head (birds are like that!)
#2 looks OK at web size
#3 is presumably beyond the point of focus (if this is the whole frame and it should all be in focus you'd have a problem, but don't believe that to be the case here.)
#4 is partly OK, is it the whole image or a crop?
John K
Last Edited by JAK on 16/08/2017 - 17:39

JAK

Link Posted 16/08/2017 - 19:07
Further to that, suggest taking a flat image such as a brick wall at various focal lengths and see what that produces.
John K

sebas77

Link Posted 16/08/2017 - 19:16
sebas77 wrote:
do some tests, those areas could simply be out of focus. At that focal range, you can expect to be everything in focus. So if you were focusing something else (like it seems it is the case) it's normal.

correction: I meant you can't expect to be everything in focus

Mike-P

Link Posted 16/08/2017 - 19:44
As soon as I saw the pictures I said to myself - Sigma lens.

My 50-500mm used to be exactly the same, if the background is grass or similar then it comes out looking just like that ... as if the IS had thrown a wonky. Main subject was always fine though.

Did have to send mine back because it wouldn't lock focus at 500mm.
No equipment list here but thanks for taking an interest. My Flickr

michaelblue

Link Posted 17/08/2017 - 06:37
Mike-P wrote:
As soon as I saw the pictures I said to myself - Sigma lens.

My 50-500mm used to be exactly the same, if the background is grass or similar then it comes out looking just like that ... as if the IS had thrown a wonky. Main subject was always fine though.

Did have to send mine back because it wouldn't lock focus at 500mm.

Interesting, Mike.
As you say, the main subject is ok .....unless it's small in the frame (as in the first image here)
Did it still produce this effect after you got it back?

Here's one taken closer to the subject with a clean background:


Regards,
Michael
My new website:link

Mike-P

Link Posted 17/08/2017 - 18:15
Yes still did It when it came back.

I have seen the same thing on the Sigma 100-300mm f4 but to a lesser degree. I think it's just a "feature" of certain Sigma lenses.
No equipment list here but thanks for taking an interest. My Flickr

jeallen01

Link Posted 17/08/2017 - 21:28
michaelblue
FWIW, which body, and what focus setting (spot, small area, large area, etc.), were you using ?
K-3 II, K-3 and a K-70 from SRS (having now relegated the K-30 with the Hacked K-50 f/w to being a backup body) , & some Sigma and Pentax lenses (and a lot of old 35mm gear!)
Last Edited by jeallen01 on 17/08/2017 - 21:29

michaelblue

Link Posted 17/08/2017 - 22:07
jeallen01 wrote:
michaelblue
FWIW, which body, and what focus setting (spot, small area, large area, etc.), were you using ?

I tried it on two different K5's and a K3ii. It's the same on all three.
All with spot focus setting, it's worse at the longer focal lengths

Here's two I took today at 290mm with the K5




Regards,
Michael
My new website:link
Last Edited by michaelblue on 17/08/2017 - 22:07
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