Nikon d750: am I seeing things?

No filter on the lens. No hood. No post whatsoever.

I bought the camera last fall, and then a family member's illness took my time/attention. Just getting to really seriously start using the camera this month. This is the second time I have noticed this sort of naturally occurring gradient in my photos. Does anyone else notice what I am noticing? Kit 24-120 lens, on as you can see a very sunny day on the Blue Ridge Parkway near Asheville, NC last week. I checked my serial number as I thought maybe my unit is part of the shutter recall, though I'm not really sure what results people are seeing with that condition - mine is not recalled. I did just last night update the firmware - I was actually one update behind already so I went from 1.10 to 1.12.

The first time I noticed this, I thought maybe I was imagining things. Any thoughts?

naturally occurring gradient in my photos.

Can you explain what you meant by "gradient" in this photo?

I am seeing a beautiful sky with an underexposed foreground. You used Manual exposure mode.

Personally, in most situations I let Nikon determine the exposure in Aperture Priority with Center-weighted metering. If the difference between highlights and shadows are far apart then perhaps some bracketing shots.

Good luck with your new camera.

If you are referring to the slightly darker upper left hand corner of your image, it might be lens vignette.

Since you are using Lightroom, try opening the image in the Develop module and apply lens correction. I believe Lightroom comes with the correction for your particular lens. See if that helps.

As others have noted, you exposed for the sky. Now if you just had one exposed for the ground, you could put them together as an HDR image.

Can you explain what you meant by "gradient" in this photo?

 

If you are referring to the slightly darker upper left hand corner of your image, it might be lens vignette.

 

Yes - that is what I meant. I have never seen that before. Is this common?

I will try using the lens correction in Lightroom - I'm on the trial version before I sign up for the subscription but I believe I saw that in the develop module.

Thanks all!

I will try using the lens correction in Lightroom - I'm on the trial version before I sign up for the subscription but I believe I saw that in the develop module.

Since you are using Lightroom, try opening the image in the Develop module and apply lens correction.

Spent no more than 5 minutes in LR from beginning to finish - using the Shadow and Dark sliders and bgelfand's suggested "vignette" feature in Lens Correction, played with Curve to add contrast. Is it better?

Spent no more than 5 minutes in LR from beginning to finish - using the Shadow and Dark sliders and bgelfand's suggested "vignette" feature in Lens Correction, played with Curve to add contrast. Is it better?

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I do think it is better. Thank you for the assistance! Lots to learn about this new camera - the good thing about that is, I just get to shoot more in order to do that!

If the gradient is in the camera's shutter, it should be the same no matter what lens and what focal length you use. If you aim at the sky with the lens at 24, and see the gradient, you should see the same thing if you zoom it. Try something safely in the middle, like 60. Is it the same? If it's different, I'd doubt it's the shutter.

If it's a shutter issue, I'd have thought it would behave differently between very low and very high shutter speeds, since the shutter operates quite differently when below and above sync speed. Duplicating the conditions that give you the problem, what happens if you vary the shutter speed only. You can set Auto ISO and S priority, and try a very slow and a very fast speed.

Spent no more than 5 minutes in LR from beginning to finish - using the Shadow and Dark sliders and bgelfand's suggested "vignette" feature in Lens Correction, played with Curve to add contrast. Is it better?

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Zooming in on the left top corner i still see "strange patterns" which do not show up on the remainder of the picture, so : was the sensor of the camera "wet cleaned" possibly leaving some "residu streaks" ?

Zooming in on the left top corner i still see "strange patterns" ... " was the sensor of the camera "wet cleaned" possibly leaving some "residu streaks" ?"

 

 

Hmm... don't see it. Don't forget that software manipulation after capture could have changed something that's not related to the original capture.

If the gradient is in the camera's shutter, it should be the same no matter what lens and what focal length you use. If you aim at the sky with the lens at 24, and see the gradient, you should see the same thing if you zoom it. Try something safely in the middle, like 60. Is it the same? If it's different, I'd doubt it's the shutter.

 

If it's a shutter issue, I'd have thought it would behave differently between very low and very high shutter speeds, since the shutter operates quite differently when below and above sync speed. Duplicating the conditions that give you the problem, what happens if you vary the shutter speed only. You can set Auto ISO and S priority, and try a very slow and a very fast speed.

I will try this and see what I come up with. Thank you!

Zooming in on the left top corner i still see "strange patterns" which do not show up on the remainder of the picture, so : was the sensor of the camera "wet cleaned" possibly leaving some "residu streaks" ?

YES! I didn't want to mention that because I really thought I was seeing things. There are definitely strange lines showing up in both the original and Mary's edit. You can see them if you look at the left edge of the photo where the hill meets the sky - there are lines that sweep on a curve from that point up toward the middle top edge of the photo. I have never cleaned this camera's sensor and I have less than 1k photos taken. Perhaps the sensor NEEDS a cleaning..

It could b the camera; it could be the lens.

Do you have another lens for the camera, say a nice 50mm prime? If so, try it and see if you get the same effect.

Hmm... don't see it. Don't forget that software manipulation after capture could have changed something that's not related to the original capture.

I see them in the Original picture as well, when zooming in my browser to 300% they become clearly visible in both examples..

Are we talking about the curved lines with a centre of rotation well outside top left of the frame?

If so, those arcing lines look like JPEG compression lines. ie the zone boundaries of 'same' colour/tone zones, which in this case are concentric stripes..

A Zoned Gradient is a pretty sure sign of false JPEG creation.

I don't suppose that you have a polarizer filter In front of the lens do you?

Nope, no filter.

A Zoned Gradient is a pretty sure sign of false JPEG creation.

What does 'false JPEG creation' mean? Have I done or set something wrong to cause this?

When a JPEG is made from the native RAW data file the camera sensor makes, it compresses the data to make it smaller. The compression in Nikon DSLRs can be mild, mid or strong. AKA Fine, Normal and Basic.

The JPEG algorithm saves space by comparing adjacent pixels. If they are deemed near-identical then the info for the similar pixels is grouped together rather than saved for every pixel. The 'trouble' comes when the level of near-identical is lowered to similar and then vaguely similar. What this does to a smooth tonal or colour gradation like a sunset is render it into similar zones, so in effect posterizing it. What should be 100 varying tones from red to yellow, is now 10 tones from red to yellow and the result is you can physically see the similar tone-bands as stripes.

This can occur in camera if the JPEG setting is set to BASIC. It becomes alot worse if the actual pixel number is set for the pic to SMALL (rather than MEDIUM or LARGE) as the similar bands are made of fewer pixels. So BASIC SMALL has the worst resilience to visual colour/tonal banding.

The arcing effect, centred top left for pic 1, top right for pic 2 is simply showing where the darkest area is to 'start' the banding.

However as you shoot RAW, these compression artefacts can only occur post capture, ie in making a JPEG image from a RAW file in Lightroom, DxO etc. Sometimes the limitations of on-line use force high levels of compression as there is a file size limit as-well as a pixel count limit to upload images to the site.

False JPEG Creation, is a clumsy way of saying that the software alone created the stripes, they were never there. However, the choices made in the conversion are usually human:)

PS.

No filter on the lens. No hood. No post whatsoever.

Apart from the RAW conversion and the subsequent resizing and compression for online submission to Photo.net........

I guess if you could post a link to the original RAW.... I could get to see what you actually took, to see if it's a hardware or software issue

PS.

 

Apart from the RAW conversion and the subsequent resizing and compression for online submission to Photo.net........

 

I guess if you could post a link to the original RAW.... I could get to see what you actually took, to see if it's a hardware or software issue

True!

I'm going to see if this works...uploading the original NEF...

I see we can't upload that file type. wonder if i can message it to you.

Rennee sent me the original file and the pic below is a RAW conversion to highlight any 'funny stuff' that's otherwise barely visible.

It is not meant to be a example of how to make a nice conversion....;)

Apparently there was no lens hood, so the slight radialness of the 'rays', and the sun star (?)... maybe weird flare? There is some tone-banding, but that's only because the sky contrast has been overly emphasized and then JPEGGed.

There's a couple of dust bunnies, but again, the excessive contrast has made them look HUGE!

There's also some natural darkening of the left-hand sky that seems entirely normal.

Sorry Renee, ...apologies for name typo...:oops:

It's all good; it's been misspelled much more disastrously than that. And I have also been called worse things. haha