Focusing problem?

heron_AI

heron_AI

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59
Name
Mattias
Edit My Images
Yes
Hello,

I shoot with a Nikon D5600 with Sigma TC 1.4x and 150-600mm Contemporary. Equipment is only a couple of months old and when I got it I checked for back and front focusing but it looked dead on. Although this was done at a distance of six meters only, I got it confirmed by using Live View focusing; there was no difference between PDAF and CDAF. Yesterday I was out shooting and I noticed that the pictures were no longer sharp, I shot at distances around 30 meters. Looking through the viewfinder I think it's not as sharp as it used to be, although a bit difficult to verify.
When I came home I cleaned everything thinking it would fine, but today when I went out to shoot some birds again I noticed that virtually all 600 pictures are blurred. I was lying down with support for lens/camera and shot with and without optical stabilizer. It was really sunny so all pictures were shot around 1/1250s.
I again tested shooting at a focus chart and I don't think it's off, although it should be done at 30 meters, but looking at the pictures from today I wonder if focusing is really the problem, it's like everything in the picture is blurry. Is the lens broken? Also, can a lens change focus over time? What do you think, below are two pictures. I use continuous AF and back button focus.

https://www.dropbox.com/s/dtv0hq3gglvycnz/DSC_0090.JPG?dl=0
https://www.dropbox.com/s/vhi7tdpt3hed0sv/DSC_0336.JPG?dl=0

This picture was taken a week ago (it's modified):
https://www.dropbox.com/s/745cu99qd7pugh1/DSC_0224.JPG?dl=0

Help appreciated.
Mattias
 
heron_AI said:
Hello,

I shoot with a Nikon D5600 with Sigma TC 1.4x and 150-600mm Contemporary. Equipment is only a couple of months old and when I got it I checked for back and front focusing but it looked dead on. Although this was done at a distance of six meters only, I got it confirmed by using Live View focusing; there was no difference between PDAF and CDAF. Yesterday I was out shooting and I noticed that the pictures were no longer sharp, I shot at distances around 30 meters. Looking through the viewfinder I think it's not as sharp as it used to be, although a bit difficult to verify.
When I came home I cleaned everything thinking it would fine, but today when I went out to shoot some birds again I noticed that virtually all 600 pictures are blurred. I was lying down with support for lens/camera and shot with and without optical stabilizer. It was really sunny so all pictures were shot around 1/1250s.
I again tested shooting at a focus chart and I don't think it's off, although it should be done at 30 meters, but looking at the pictures from today I wonder if focusing is really the problem, it's like everything in the picture is blurry. Is the lens broken? Also, can a lens change focus over time? What do you think, below are two pictures. I use continuous AF and back button focus.

https://www.dropbox.com/s/dtv0hq3gglvycnz/DSC_0090.JPG?dl=0
https://www.dropbox.com/s/vhi7tdpt3hed0sv/DSC_0336.JPG?dl=0

This picture was taken a week ago (it's modified):
https://www.dropbox.com/s/745cu99qd7pugh1/DSC_0224.JPG?dl=0

Help appreciated.
Mattias
Click to expand...
I haven't downloaded the images so can't really tell too well how soft/blurred they are but it looks as though there's a lot of heat haze, could it just not be this as you're shooting from such a long distance?
 
snerkler said:
I haven't downloaded the images so can't really tell too well how soft/blurred they are but it looks as though there's a lot of heat haze, could it just not be this as you're shooting from such a long distance?
Click to expand...

I honestly don't know but I have never experienced it before, not at this distance. It was like the lens was AF hunting a lot more than usual. It would be great if you could see the pictures in full size and see what you think.

Mattias
 
Have you tried shooting the lens without the TC?

Also why did you shoot without the OS? At that length, OS is a must IMO, being supported won't cause issues by using it.

As per Snerklers post, haze and atmospheric distortions such as heat can cause major issues shooting at such long lengths.

Also, what AF lens setting did you have, speed priority or accuracy?
 
Last edited:
Looking at the ground around the birds - nothing is sharp. It doesn't seem to be that nothing is in focus but rather that everything is blurred.

This would imply user error :) (Jim just posted as I'm writing)

I'd also try a different subject, and a tripod, so that you can test your lens to find out what is happening. I suspect the shutter speed is way too low for this type of shot -remember this is a crop frame camera which affects the usual 1/focal length = lowest shutter speed.
 
Yep, having looked at full size it's all a bit blurry. It could still be the haze, but what's more likely is that shutter speed isn't high enough at your effective focal length is 1260mm. I would try without TC and 1/1000 minimum, and then with TC and at 1/1500 minimum and see what your findings are.
 
odd jim said:
Have you tried shooting the lens without the TC?

Also why did you shoot without the OS? At that length, OS is a must IMO, being supported won't cause issues by using it.

As per Snerklers post, haze and atmospheric distortions such as heat can cause major issues shooting at such long lengths.

Also, what AF lens setting did you have, speed priority or accuracy?
Click to expand...

Hello!

No I shot most of the pictures with OS on, but I could see on the back screen that the pictures weren't sharp so I tried switching it off, no difference.

Sure there was haze, but to cause that much distortion? It doesn't seem right. Maybe some images were shot at 20 meters. I have never had a picture wasted due to haze on these distances. It was 7-8 deg Celsius.

AF priority is focus (accuracy).

My wife and I were about to go out and shoot some test pictures at appr. 30 meters without the risk of haze, but the battery died on me and I don't have another one. The sunlight is fading so it will have to wait till tomorrow.

It's weird, when I was shooting yesterday, when I moved to a new spot, suddenly the pictures are blurred. I found one interesting thing though, there is an AF setting, 39 points or 11 points. I don't know for sure but I think I used to have this set to 11 points but this was now 39 points. Don't know how this affects focusing since I only use 1 center focus point due to the TC. If this is the cause I would be happy.

Mattias
 
snerkler said:
Yep, having looked at full size it's all a bit blurry. It could still be the haze, but what's more likely is that shutter speed isn't high enough at your effective focal length is 1260mm. I would try without TC and 1/1000 minimum, and then with TC and at 1/1500 minimum and see what your findings are.
Click to expand...

When I got my equipment I did some test shooting, then I put on the TC and it hasn't been off since. I have shot some nice pictures hand held with lower shutter speeds, now I shot with support and I couldn't find a decent picture out of 600. If it was down to shutter speed, statistically at least a few would have been sharp.
 
kendo1 said:
No.
Click to expand...

If you look at the third picture, I took appr. 300 pictures like that with the exact same setup just a few days ago, the absolute majority were fine. Full zoom and 1/1250s with support and OS.
 
Have it your way. whatever... :)
 
snerkler said:
I haven't downloaded the images so can't really tell too well how soft/blurred they are but it looks as though there's a lot of heat haze, could it just not be this as you're shooting from such a long distance?
Click to expand...

I have been looking on the internet on how haze affect pictures and it looks like it could be the problem. Cold ground, strong sun and little wind combined with the fact I was lying down all amplify the problem. Could explain why the AF was hunting so much.
 
heron_AI said:
I have been looking on the internet on how haze affect pictures and it looks like it could be the problem. Cold ground, strong sun and little wind combined with the fact I was lying down all amplify the problem. Could explain why the AF was hunting so much.
Click to expand...
Might have been, run some controlled tests and see what you find. What were you using to stabilise the lens when you were lying down?
 
heron_AI said:
Yeah, I will do that tomorrow. I use a stuffed rucksack (the one I wear).
Click to expand...
Maybe more movement in the rucksack than you think when you press the shutter.
 
TBH you're lucky to have any decently function AF with that lens plus telecon. Your effective maximum aperture is f/8.8 at 600mm 1.4x (6.3 x 1.4). Most cameras are slow and inaccurate above f/5.6 and most Canons literally switch off the AF system when effective apertures rise above that, due to unreliable performance. But even if the AF is working, it won't perform as well.

Atmospheric pollution, dust and moisture (especially over water) effect long lens images much more than most people realise. Keep shutter speeds well up. You also have subject movement blurring in the first image, around the bird's head. Often apparently slow moving birds are actually moving very fast, in short, jerky movements.

The key to best image quality with most wildlife is not to bolt on ever longer lenses, but to get closer. Fieldcraft and patience ;)
 
Yes, as several of you have pointed out, it was heat haze that caused the blur. Took tack sharp pictures today. As wezza13 said, it's a bigger problem than I realized and it explains blurry pictures in the past (where I dismissed it as camera shake/out of focus). The blurring from heat/vapor haze was easily reproduced today when shooting at longer distances over water, but could be avoided by shooting at shorter distances and where the water was partially in shade.

Thanks.
 
heron_AI said:
Yes, as several of you have pointed out, it was heat haze that caused the blur. Took tack sharp pictures today. As wezza13 said, it's a bigger problem than I realized and it explains blurry pictures in the past (where I dismissed it as camera shake/out of focus). The blurring from heat/vapor haze was easily reproduced today when shooting at longer distances over water, but could be avoided by shooting at shorter distances and where the water was partially in shade.

Thanks.
Click to expand...
I come up with some useful suggestions now and then ;)
 
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