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-   -   Struggling with focus/sharpness (https://www.birdforum.net/showthread.php?t=363931)

falconer2406 Sunday 1st July 2018 20:49

Struggling with focus/sharpness
 
1 Attachment(s)
Hi All,

Of late i am really struggling with my 7dmk11 and 100-400 is usm mk11 lens
The attached picture taken recently, using single focal point and the camera indicating focus achieved gives me this result.

Its obvious the focal point sits right over the subject and with the camera indicating focus achieved i don't understand as to why the result is as it is.

Happy to accept finger/setting trouble but is this a lens issues?

Dave Williams Monday 2nd July 2018 17:56

I often find that the focus point indicates that it should be sharp but isn't ( and vice versa for that matter) but usually on moving subjects and at a high frame per second rate.
Is your focus problem in all scenarios or just when you attempt macro shots? Are you too close and within the focus limit distance? Maybe you need to give a few more scenarios so perhaps others can think of where you might be experiencing problems.

Vespobuteo Monday 2nd July 2018 18:05

Quote:

Originally Posted by falconer2406 (Post 3736687)
Hi All,

Of late i am really struggling with my 7dmk11 and 100-400 is usm mk11 lens
The attached picture taken recently, using single focal point and the camera indicating focus achieved gives me this result.

Its obvious the focal point sits right over the subject and with the camera indicating focus achieved i don't understand as to why the result is as it is.

Happy to accept finger/setting trouble but is this a lens issues?

Might be a back-focus issue as you seem to have correct focus behind the focus point.

https://www.the-digital-picture.com/...ment-tips.aspx

LesR Monday 2nd July 2018 18:06

To my eyes that photo looks like it is back focusing.

falconer2406 Tuesday 3rd July 2018 21:04

Quote:

Originally Posted by Vespobuteo (Post 3736953)
Might be a back-focus issue as you seem to have correct focus behind the focus point.

https://www.the-digital-picture.com/...ment-tips.aspx


Many thanks for this and the link, certainly looks interesting, i will attempt some adjustments and report back

falconer2406 Tuesday 3rd July 2018 21:05

Quote:

Originally Posted by LesR (Post 3736954)
To my eyes that photo looks like it is back focusing.

Thanks Les, certainly appears that way, i am attempting some adjustments and will report back

falconer2406 Tuesday 3rd July 2018 21:06

Quote:

Originally Posted by Dave Williams (Post 3736951)
I often find that the focus point indicates that it should be sharp but isn't ( and vice versa for that matter) but usually on moving subjects and at a high frame per second rate.
Is your focus problem in all scenarios or just when you attempt macro shots? Are you too close and within the focus limit distance? Maybe you need to give a few more scenarios so perhaps others can think of where you might be experiencing problems.

Thanks Dave the below currently applies

Hauksen Tuesday 3rd July 2018 22:36

Hi,

Quote:

Originally Posted by falconer2406 (Post 3736687)
Its obvious the focal point sits right over the subject and with the camera indicating focus achieved i don't understand as to why the result is as it is.

From using my FZ1000 in manual focusing mode with a "sharp edge highlighting" kind of live view, it's my impression that the edges of the mesh of dragonflies' wings are quite dominant, and these edges are sharp in your photograph, too.

I'd not be suprised if the algorithms used by your camera got "attracted" by these edges. It might be worth it to try different targets (like uniform graph paper) under controlled conditions (with the camera on a tripod) to see if the problem is universal.

Regards,

Henning

Vespobuteo Tuesday 3rd July 2018 23:24

Quote:

Originally Posted by Hauksen (Post 3737457)
Hi,

From using my FZ1000 in manual focusing mode with a "sharp edge highlighting" kind of live view, it's my impression that the edges of the mesh of dragonflies' wings are quite dominant, and these edges are sharp in your photograph, too.

I'd not be suprised if the algorithms used by your camera got "attracted" by these edges. It might be worth it to try different targets (like uniform graph paper) under controlled conditions (with the camera on a tripod) to see if the problem is universal.

Regards,

Henning

If that would be the case, still the AF-point(s) in-focus should have a red frame I suppose. But I'm not 100% into Canon and how they do things.

What I can see is that TS is using AF point expansion (AF-Area select mode) which means that 4 (or even 8) points around the center point might be engaged in the focusing acquirement.

So for more precise selection of focus point "Single Point AF" might be an alternative.
Still there could be a back-focusing issue though.

Setting up things in a controlled environment as you say is a very good advice btw.

Hauksen Wednesday 4th July 2018 12:01

Hi,

Quote:

Originally Posted by Vespobuteo (Post 3737474)
If that would be the case, still the AF-point(s) in-focus should have a red frame I suppose. But I'm not 100% into Canon and how they do things.

What I can see is that TS is using AF point expansion (AF-Area select mode) which means that 4 (or even 8) points around the center point might be engaged in the focusing acquirement.

I wouldn't necessarily take symbolic representation "literally" - these algorithms probably are way more flexible than the red frame suggests.

In fact, your excellent point regarding "AF point expansion" shows there's some advanced stuff going on that the symbolic representation sort of glossed over :-)

I'd say the exansion would be consistent with the autofocus detecting lots of useful edges in the frames to the left and right of the central frame, and focusing on these.

Regards,

Henning

mr_birdman Wednesday 25th July 2018 01:52

What I can see in your EXIF data are two things:

1) You have surrounding AF points enabled. I would turn these off completely where this type of high-precision focusing is needed with smaller subjects. While you may have the center point selected, the AF system may apply another point if there is not enough contrast for the selected AF point. I am not 100% certain, but I don't think DPP shows the exact point if it is an assist point. In any case, select spot-AF, the little box within the AF point, that will give you the most accurate AF point.

2) Use a lens calibration tool and fix the microadjustment. That could also be a problem, as I can see you have a value of 5 in AF microadjustment. I, personally, never had to microadjust any Canon lens with my 1Dx MkII that is my main body right now. I also never needed to do MA on any other Canon EOS body with a Canon EF lens. Not to say, that it is always the case. However, my new Sigma 500mm f/4 DG OS HSM Sport needed +2 at 500mm, +4 at 500mm + 1/4xTC and +6 at 500mm + 2xTC. So be sure your camera needs the MA done!

I do think it is most likely the first point with the surround assist points. I ONLY EVER use the 9 points or the 5 points (both 9 and 5 include the selected AF point) if I am shooting a flying bird against a clear background (EG. sky).

Best of luck!

esmondb Friday 17th August 2018 20:54

Quote:

Originally Posted by falconer2406 (Post 3736687)
Hi All,

Of late i am really struggling with my 7dmk11 and 100-400 is usm mk11 lens
The attached picture taken recently, using single focal point and the camera indicating focus achieved gives me this result.

Its obvious the focal point sits right over the subject and with the camera indicating focus achieved i don't understand as to why the result is as it is.

Happy to accept finger/setting trouble but is this a lens issues?

Was this shot handheld or on a tripod? If handheld I'd immediately suspect a slight movement between acquiring focus and releasing the shutter - the depth of field is so shallow it wouldn't take much movement and that's a heavy enough lens


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