azemon Loc: Saint Charles, MO, USA

Folks,

I was surprised by some loss of detail in a photo that I took a couple of days ago. I think that I am looking at JPEG artifacts but would appreciate confirmation or other ideas. I normally shoot JPEG because for the vast majority of my photos, the JPEG compression doesn't cause my any pain. I think that it bit me this time, though.

The subject is a couple of bald cypress tree trunks so there is a ton of rapidly changing detail in the source material. I shot this with a Nikon Z 5 in Fine* mode. For those of you not familiar with Fine* mode, it is Nikon's Fine mode with the compression tuned for better detail instead of file size.

Nikon Z 5, Fine* mode
Tamron 150-600 VR G2 at 500mm, VR3 mode
F11
1/1600
ISO 4000

I am attaching a crop of one of the tree trunks. You can see that a big chunk of the tree has no detail. However, there are portions near the top which are clear. There are also branches hanging in front of the blurry area which are also clear. Also attached are the camera original file and (just for fun) my final B&W version (which I like except for the lack of detail).

Thanks,
-- Art Z.

(Download)


(Download)

Brian S. Loc: Oak Park, MI

Why such a high ISO and shutter speed?

Ysarex Loc: St. Louis

My first reaction is high ISO noise filtering. Got the raw file?

gvarner Loc: Central Oregon Coast

Trying to discern sharpness in a drab subject under flat light is a difficult task. I like the B&W. Note that the roots near the bottom with all the lighting hilights appear sharp.

Jerry G Loc: Waterford, Michigan and Florida

There really is a lack of detail throughout the entire photo. The focus seems ok but it reminds me of excess noise reduction, maybe in camera because of high iso?

Fotoartist Loc: Detroit, Michigan

The wind must have been blowing hard for 1/1600 / sec. shutter speed.

Linda From Maine Loc: Yakima, Washington

Azemon, photography technique lesson #1 is to learn how to appropriately select - or interpret - your shutter speed, aperture and ISO. Auto modes are fine as long as you know the ramifications of what is happening. Can you see your settings on your screen before you shoot?

Linda From Maine Loc: Yakima, Washington

Another thought: did you set your ISO manually? Looks like you used aperture priority and it seems unlikely the camera would choose that high a shutter speed/ISO combo.

therwol Loc: USA

My guess is that the ISO is set too high for this scene. There is no question that all cameras suffer from some image degradation as the ISO goes up. I reach a threshold with my D850 of 2500 to 3200 before I really start to notice it. It's acceptable if you need it in low light situations, but in bright sunlight? Try keeping it below 800.

azemon Loc: Saint Charles, MO, USA

Ugh! I just noticed that my title is "Is these JPEG artifacts." Sheesh. I'm not that ignorant. Really. I'm not sure whether I meant to type "Are these JPEG artifacts" or "Is this a JPEG artifact" but I am quite sure that I was still asleep when I did it. Silly me.

azemon Loc: Saint Charles, MO, USA

To the matter at hand:

My thanks for the folks who have confirmed that this is some sort of processing issue within the camera. Perhaps JPEG compression. Perhaps high ISO, though I doubt it. I think that I will retry the shot in RAW mode the next time I am at the Shaw Nature Reserve. It will be an interesting experiment.

Regarding the ISO setting, the Z 5 does really well at ISO 4000. Ken Rockwell has a nice set of controlled images at https://kenrockwell.com/nikon/mirrorless/z5.htm#perf (scroll down to "High ISO Performance") for an objective comparison.

Regarding shutter speed and camera settings, I know from experience that I need a pretty high shutter speed to freeze motion with that long, heavy lens. My hands aren't as steady as they were when I was younger and that works against me, too. It was a windy day, I was doing a lot of bird photography. I set the aperture to what I want and enable auto-ISO with a minimum shutter speed that I like. Then I let the camera adjust the ISO as needed. It's kind of bass-ackwards for a guy who grew up shooting film with ISO as the one thing which could not be changed in the middle of a roll of film but it has proven surprisingly effective.

With the Z 5, as the ISO creeps up, I start to see noise in places where I want buttery smooth graduations of tone. Personally, I'd rather have that noise than deal with too low a shutter speed or having to select an aperture that I don't want.

Thank you, everybody, for your time and thoughts.

Cheers,
-- Art Z.

fredpnm Loc: Corrales, NM

Bottom line, I think for most who responded to the issue...regardless of your stated reasoning...the likely cause is that your f/11 is too high, move to a lower number (f/5.6 if your lens can do it), your shutter speed is too high, something slightly above 1/500 will do, and set the ISO to as low a number as you can - let the camera decide if necessary, but certainly not over 500. From what we see in the images you provided it is a sunny day and an ISO of 100 or so is clearly called for. The fact the Z does well at 4000 is not important for this image. Use spot focus and make sure it's on the tree(s) if the trees are to be your subject. For what your issues seem to be, shooting this same image in RAW will not result in a better photo (depending on just how you have the camera set to process the image to a JPG file).

p.s. if the lens is heavy or your shake hand holding the camera/lens - get a tripod!

azemon Loc: Saint Charles, MO, USA

These are, indeed, ISO artifacts. I shot a series of test images of a tree using the same lighting, camera settings, lens, focal length, and distance to subject. I used ISO values from 100 to 12800. Using 100 as the baseline, I can see the same artifacts appearing at ISO 4000 that I got on Monday.

I uploaded all of the JPEG images here https://gallery.wonderart.us/Photography/Nikon-Z-5-ISO-Tests/
(Sorry no raw files. My SmugMug level doesn't support them.)

Thank again, folks. It's a good day when I learn something new.

-- Art Z.

fredpnm Loc: Corrales, NM

Best of luck with future outings.

Ysarex Loc: St. Louis

No, ISO doesn't cause artifacts. You're seeing the fine detail smeared by noise reduction filtering. In the camera's shooting menu find High ISO NR and turn it off. That'll stop the smearing of detail at higher ISO values.

ISO correlates with noise. Normally you raise ISO because you need to reduce exposure and reducing exposure causes noise. ISO most commonly causes a loss of DR and lightening of the camera's output JPEG. Severe noise can interfere with detail but it doesn't smear it as your getting. Turn high ISO NR off.