Nikon Z 800mm - Is this heat distortion?

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BillyBob_Aus

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Hi all,

New owner here of the Nikon Z 800/f6.3

Im having a lot of trouble with "muddy images" (which I suspect is heat distortion), but as this is my first super telephoto I'm not certain.

It is coming into summer here in Australia, so the sun is warming up. On the weekend I took these images around noon. Sun was out and starting to warm up.

The bird was only about 6 metres (20 ft) away from me. The tree maybe about 100 metres (330 ft).

Bird photo: 1/800, f6.3, ISO 140. Focus point was the eye.
Tree photo: 1/800, f6.3, ISO 100. Focus point was the tree in the middle.

Although the sun was out, it surprised me that I would be getting heat distortion when the bird was only a few metres away??

I have tested the lens early morning and late in the day, and images seem better - although I do find in a burst of say 10 images I'll get 50% perfectly sharp on the birds eye, and the other 50% not. Not sure if this is considered normal or just my lack of experience? I tend to use Auto area AF with subject detection, and then handoff to 3D tracking with subject detection.

So what do the experts here think? Is this heat distortion in the attached samples?

Thanks


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I don't have the 800 pf. It could be heat distortion. If it is not much you can do about that given the conditions. However, I see you are shooting at 1/800 and ISO 100. I would try jacking up your shutter speed to around 1/2,500 and increasing ISO to 500. This might help. I know when I shoot my 180-600 at 600 on a Z8 I tend to get better shots at higher shutter speeds. Just a thought. Good luck. Ken
 
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BillyBob_Aus said:
Hi all,

New owner here of the Nikon Z 800/f6.3

Im having a lot of trouble with "muddy images" (which I suspect is heat distortion), but as this is my first super telephoto I'm not certain.

It is coming into summer here in Australia, so the sun is warming up. On the weekend I took these images around noon. Sun was out and starting to warm up.

The bird was only about 6 metres (20 ft) away from me. The tree maybe about 100 metres (330 ft).

Bird photo: 1/800, f6.3, ISO 140. Focus point was the eye.
Tree photo: 1/800, f6.3, ISO 100. Focus point was the tree in the middle.

Although the sun was out, it surprised me that I would be getting heat distortion when the bird was only a few metres away??

I have tested the lens early morning and late in the day, and images seem better - although I do find in a burst of say 10 images I'll get 50% perfectly sharp on the birds eye, and the other 50% not. Not sure if this is considered normal or just my lack of experience? I tend to use Auto area AF with subject detection, and then handoff to 3D tracking with subject detection.

So what do the experts here think? Is this heat distortion in the attached samples?

Thanks


View attachment 101382View attachment 101383
Click to expand...
One way to tell if you are experiencing heat distortion while shooting is whether you are getting a consistent autofocus lock. Many times when I have a heat distortion problem, you can here the chatter of the motor and the lock indication(white dot) is flickering.
 
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Yep, looks like heat haze to me. Not much you can do unfortunately apart from shoot in different conditions or embrace it and make it a feature (needs to be more extreme for that though).
 
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In cooler conditions i don’t seem to have a problem, but the moment there is sun and a bit of warmth, I struggle to get a clear shot.

If the lens was faulty, or the issue is me, then I’d expect the images would be bad all the time, but they aren’t.
 
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Whatever it is, it is something to investigate.
As the problem occurs when heat distortion is more likely then heat distortion is most likely the primary course - particularly with the distant tree shot.
Looking at the bird shot as you note 20 feet focus distance is a bit close for significant heat distortion. On the other hand the bird is on light coloured grass where the temperature could be very different to where you were taking the photograph.

As has been mentioned the shutter speed was a bit low for 800 mm unless you have extremely strong muscles or use good long lens technique on a good tripod.
It is worth experimenting with higher ISO and faster shutter speeds.
Shots are as sharp as they should be when the sun is not out so the lens is okay.

The problem seems primary an issue of finding out how to get more shots of the quality you want when the sun is out.
A caution – when significant heat distortion is present there is now way I have discovered to get critically sharp shots
 
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Len Shepherd said:
Whatever it is, it is something to investigate.
As the problem occurs when heat distortion is more likely then heat distortion is most likely the primary course - particularly with the distant tree shot.
Looking at the bird shot as you note 20 feet focus distance is a bit close for significant heat distortion. On the other hand the bird is on light coloured grass where the temperature could be very different to where you were taking the photograph.

As has been mentioned the shutter speed was a bit low for 800 mm unless you have extremely strong muscles or use good long lens technique on a good tripod.
It is worth experimenting with higher ISO and faster shutter speeds.
Shots are as sharp as they should be when the sun is not out so the lens is okay.

The problem seems primary an issue of finding out how to get more shots of the quality you want when the sun is out.
A caution – when significant heat distortion is present there is now way I have discovered to get critically sharp shots
Click to expand...
Thanks for your reply.

When I took the bird shot I was under cover in the shade, so where I was was cooler than the bird out in the full sun.

I did some more tests today in my street just using static objects:

- During the day when the sun is out, I can't get anything past about the 10 metre mark sharp. It's all hazy.
- Repeated the same shots this evening once sun was going down, and pretty much every shot was very clear. Even out to 150-200 metres (500-650 ft) was clear and sharp. Even hand holding down to 1/100 with VR was fine.

So it certainly seems issue is only there during the day when sun is out. I'm just surprised it's such an issue on short distances like the bird example I posted.
 
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BillyBob_Aus said:
When I took the bird shot I was under cover in the shade, so where I was was cooler than the bird out in the full sun.
Click to expand...

If the Sun was shining along the path to the subject that's where the heat distortion is happening most likely.

I think before you make any conclusions you have to do some testing, including tests that you can repeat. I note that you have a shutter speed of 1/800, but no mention if a tripod is in use for these shots. I've always prided myself on my ability to hand hold a camera steady even when I'm using lower shutter speeds than the normal 1/focal length rule, but found as I stepped up in the camera resolution I was having to use faster shutter speeds. 1/FL was fine on my D700, but I had to go to 1.5x with my D810 and 2x with my D850.

I've also seen on here that sometimes vr can give issues with some lens and shutter speed combinations.

If I were you I'd use a test chart and have the camera on a tripod and a shutter speed higher than 1/1600 and maybe put some hand pressure on the rig too. Fire it on the self timer or remote release and start under 10 metres. That way you are being consistant.
 
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More info would help. Were you hand holding or on a sturdy tripod? Was VR on and if so, normal or sport? Could be heat haze (I've had it on cold days at 9am), could be technique (long lenses require more exacting technique), could be lens hood generated heat haze (see the video Steve did). If your af has trouble focusing, ie, slow to acquire or jittery, chances are heat haze is present. Heat haze will affect the af system's ability to get proper focus. Steve also has some good videos on long lens technique.
 
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Thanks for the further replies.

All shots have been hand held.
I have tested using a test chart indoors (again hand held), and image is sharp and clear.

I have tried with VR in sports and normal modes, and also with VR off. None of this made any improvement in the hazy images.
I also tried with the lens hood off - didnt make any difference.

Ive watched Steve's videos on this issue too, I was just surprised how prevalent this issue has been for me! I was especially surprised to have it at such a short distance too.

I'll keep doing more tests the next few days, but so far the pattern seems to be I get clear and sharp images early and late in the day, and hazy/muddy images during the day.
 
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BillyBob_Aus said:
Thanks for the further replies.

All shots have been hand held.
I have tested using a test chart indoors (again hand held), and image is sharp and clear.

I have tried with VR in sports and normal modes, and also with VR off. None of this made any improvement in the hazy images.
I also tried with the lens hood off - didnt make any difference.

Ive watched Steve's videos on this issue too, I was just surprised how prevalent this issue has been for me! I was especially surprised to have it at such a short distance too.

I'll keep doing more tests the next few days, but so far the pattern seems to be I get clear and sharp images early and late in the day, and hazy/muddy images during the day.
Click to expand...

Are there any atmospheric conditions in your area? Like airbourne dust or smoke from anywhere? If your outdoor testing so far has been local or in one place try going somewhere completely different and further away and see if you get better results.

Does a local map show anything nearby that could be producing pollution? If so you will have to start checking the wind direction to see if that might be the cause.
 
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dabhand16 said:
Are there any atmospheric conditions in your area? Like airbourne dust or smoke from anywhere? If your outdoor testing so far has been local or in one place try going somewhere completely different and further away and see if you get better results.

Does a local map show anything nearby that could be producing pollution? If so you will have to start checking the wind direction to see if that might be the cause.
Click to expand...
I’ve tried 2 completely dirrferent areas. One was out in the country, the other in the city hundreds of miles away.

Only consistent atmospheric conditions are it’s almost summer here, and lots of sunshine. No smoke, pollution etc.
 
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The first image looks more like false focus. I often get beak AF when the bird is looking towards me. Probably paired with heat distortion.
The latter can occur even at very close distances, especially when you are so close to the ground.

Your second bird image proofs that the lens is working fine.
 
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