As requested, a Play Raw
I have tried this three ways, without AI, using the native noise reduction, with AI using the raw denoise model, and with the AI denoise model.
I am not posting an XMP, so as not to prejudge how others handle this:
_CTW2287.NEF (61.5 MB)
This file is licensed Creative Commons, By-Attribution, Share-Alike.
Thank you! 
I was really interested in comparing denoising on your image as well. I’m at the moment not at home, but will give it a try later on.
Home again. Traditional denoising, aiming to preserve as much detail in the fur as possible.
I feel defeated by the noise. I haven’t included the xmp because it is DT 5.6 with AI denoising producing a tiff as part of the processing.
Still defeated by the noise, but now non-AI denoising DT 5.6
_CTW2287.NEF.xmp (18.7 KB)
Did not find this beauty easy to work on. Have not much ‘noise experience’.
Beware xmp is from dt 5.6.0
Maybe better to explain my process as not all of you are on dt5.6.
denoise, only chroma noise
denoise squirrel and background separately, used manual masking, extra denoise on eye only
retouched away ugly color blob in right upper corner
raised exposure
strong vignette with exposure module and elliptic mask
tweaked color calib to warmer color as picture was taken at 7am in morning
DoS, sharpness, normal only on squirrel
Had contr equa only on squirrel at 50% but switched it of as it accentuated the noise too much to my liking
enhancing with color balance rgb
agx on cam settings, bit tweaked
loc contr only squirrel highlight protected
framing taking replacing white line with mint green from picture
Fun to do, find the noise very hard at ISO 14.400. As said I’m no expert at this.
I had the same problem. My best result was to use the raw denoising model. Still something that I need to play with a bit more.
On this take I used a mixture between AI denoising and traditional denoising:
First AI denoising set to 50%
looks for me convincing. No plastic look and still a bit of noise, but quite regular. I don’t have the feeling, that many details were killed.
Looks quite nice to me given a ISO 14400 picture. Just on the edge of plastic appearing and nice sharpness.
Indeed quite difficult to work with. Tried using the new denoise model but still the results weren’t perfect. I guess it’s one of the few photography fields where getting a new up to date camera would solve a lot of issues. As a landscape/cityscape photographer I’m relieved that this isn’t the type of files I come home with, I’d be very frustrated
Thanks for doing that is something I’m wanting to study
There is a theory that releasing Pine Martins is the way to preserve the Red Squirrel against the Grey the heavier grey squirrel cannot escape onto lighter branches from the pine martin who also would cause them to snap
Mind you with Bumble bee conservation I understand the situation is reversed with the European species being the problem in the Americas
I wouldn’t expect too much improvement on newer sensors regarding noise. The sensor of the Nikon D850 should be still quite competitive:
https://www.dpreview.com/reviews/image-comparison/fullscreen?attr18=lowlight&attr13_0=nikon_z8&attr13_1=sony_a7rvi&attr13_2=nikon_d850&attr13_3=canon_eosr5ii&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=25600&attr16_1=25600&attr16_2=25600&attr16_3=25600&attr171_3=3&normalization=compare&widget=757&x=-0.8841336918939685&y=0.05788533295063155
Exactly. The noise in this image would be solved with a lower shutter speed, possibly 1/125 or 1/250 would be plenty if the lens is well stabilized.
And the squirrel isn’t moving too quickly.
Yeah of course but he seems to be eating, there would probably be a little motion blur around his mouth but nothing major compared to the blur caused by the denoising. Of course we say this in hindsight, in the moment it’s hard expose properly a lot of the times due to quickly changing variables
Some make a habit of making a small series with subsequent longer exposure times. Thus afterwards being able to find the best with minimal noise.
(Cries in 1/4000s bird photography)
