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Although I declare myself very satisfied with my Nikon Coolpix P900, I've had in my recent trip in South America numerous pictures blurred by a random artifact, and I would like to know how to avoid that in future.

The problem occurred always at high altitude (between 3000 and 5000 meters above sea level), in full daylight (very high EV, high percentage of blue in the colour temperature), in the upper zone of the optical zoom (between 1,000 and 2,000 mm of 35-mm-equivalent zoom factor).

The artifact is a random spot of blurred pixels just in the middle of correctly focused ones. Sort of an artistic post-production filter of the "Impressionist painting" style. Something like you have just done a watercolor painting and you gently poke with the point of your fingers on the fresh paint, leaving some of it untouched. Where you touch, the image gets blurred.

Three examples are available here.

I was working with Auto White Balance, mostly shooting with P (Program) mode, in max-dimension JPG format (the P900 does not, unfortunately, allow RAW pictures) and Noise Reduction factor on Normal (where + and - are also available).

Most of the other images, shot at the same extreme distances, are perfectly sharp. When they were out of focus, the image was just faded, but not full of artifacts like these.

Any idea on the origin of the problem, and how to avoid it?

Setting the noise reduction on "-" rather than on "Normal"?

Thanks, folks...

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  • Could that be due to Heat Haze?
    – flolilo
    Mar 9 '18 at 13:14
  • Good question! Would you mind uploading some of your example photos into your question, rather than linking to them? That way, if the URL to those examples changes in the future, this question will still make sense to future readers. Thanks! =)
    – scottbb ♦
    Mar 9 '18 at 13:55
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    @flolilolilo It looks like heat haze might be part of the problem, but based on the examples, I get the distinct impression that some over-aggressive digital algorithm is causing the impressionistic effect.
    – scottbb ♦
    Mar 9 '18 at 13:58
  • Thanks both flolilolilo and scottbb. I have not posted the original pictures due to size limitations (the upload here is limited to 2MB, these pictures are by far larger and I did not want to downsize them, to avoid further corruption of the image). The haze is definitely my #2 option, although I have to say that similar Impressionist effect occurred also on totally dry areas (that region is one of the driest in the whole globe...). My #1 vote goes for an over-aggressive digital algorithm: does anybody know if and where I can find a patient ear@Nikon listening to me on this matter?
    – BigBoozer
    Mar 9 '18 at 17:55
  • What ISO? Is it different between the affected and non-affected images at the long focal lengths? How are you supporting the camera (i.e. handheld or on a stable tripod)?
    – Michael C
    Mar 9 '18 at 21:00
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The blur is due to heat haze. I have had this exact same issue happen when taking pictures of birds on lakes. Just this winter I had the same issue when taking photos of snow geese. The only way I've found to "fix" the blur was to either close my distance between the subject and myself, wait for the haze to dissipate or increase my elevation so I wasn't shooting directly through as much haze.

The artifacts are probably coming from the image distortion correction on the camera's Expeed processor. I searched the manual and it doesn't look like there is a way to turn off the distortion correction.

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