I took a whole series of photographs of local listed buildings, so I could add them to wikimedia - until I saw the results.
D5500 with Nikkor 24-120mm VR 3.5/5.6G 50mm ISO 100 1/320s f4.8
Full picture [jpg ⅓ actual size, click-through]
detail - screen-snap at x2 zoom
Pictures taken hand-held, but I'd say that's too much distortion to be motion-blur at 1/320, reinforced by the fact that all my pictures are similarly affected, even faster exposures. I was bracketing so some are at 1/600 or higher. VR was on. Also I had a polariser on to help with the clouds.
Detail of a similar picture taken the same day with just the kit lens at 18mm, 1/125 f4, also with CPL - same 2x magnification as above.
It's not perfect, but it shows nothing like the blurring of the 24-120
I've noticed this 24-120 showing bad colour aberration before, when using it on extension tubes for macro - so even under highly controlled conditions with good lighting & multiple manual exposures on a focussing rail, it still isn't good.
I would have otherwise blamed the CPL, perhaps giving some internal reflection, but I really have to come to the conclusion that this lens doesn't focus properly on my camera.
I have no means to tweak & save the auto-focus in-camera, it's not a feature on the D5500.
I would also perhaps blame the relatively wide aperture, maybe I should have stopped it down - but the kit lens turned out sharper at a wider aperture.
Is this just a "duff lens" in the broadest terms?
[I have to say I've never liked it much, but I was given it, so never look a gift horse in the mouth]
Is there anything in my admittedly newbie technique I can do to improve this, or is it just time to get a 'better lens'?
(Not used for this particular comparison, but I also have a 50mm 1.4 & a Tamron 70-300mm f4-5.6 neither of which shows such glaring focus-fail)
I went back to the location to try some further experiments. I removed the CPL from the equation, but added a variable ND to my 50mm to reduce light & get longer exposures, just for comparison. These are [very] quickly assembled from my results...
[again, click to see larger]
a) one of the bracket -1 EV shots from the first session, with filter & VR [to eliminate long exposure shake from the equation]
b) through d) no filter, no VR
b) tighter aperture
c)/d) original aperture, fast exposure
50mm for comparison
a) 1/40 to show how steady I can hold the camera - not perfect but OK-ish.
b) similar settings to my problem pics
c) comparison at tighter aperture
d) comparison at wide open