Careful with tuning. Only do it if you are seeing consistent front focusing or back focusing. In those cases it helps,
+ 1
This implies a photographer perceiving a problem - which on investigation might not be the lens - knows how to recognise front or back focus.
for random mis-focus (both front and back) it's worse than doing nothing. In short, make sure you're fixing the right issue.
Agreed.
Also, I agree - I think those two images are on the slightly soft side.
Agreed
The 180-600 isn't going to give you 600TC level sharpness, but it's usually better than that.
Part agreed.
"Part" because I do not have access to the 600 f4.
I do have the 400 f6.3, the Plena and the 85mm f1.2 to set the highest resolution standard possible from 45 MP - when combined with excellent technique.
Also, I'd recommend using a tripod for testing - even with VR, hand-holding is a huge variable.
I regard a good tripod as essential when critical comparison between lenses at 200% or more (on a good monitor) is the aim.
What standard do I expect from my 180-600?
Comfortably more resolution than needed for a top quality A3 print - with a probability of a good A2 print - with my level of technique.
Some images posted seem not to be reaching this standard - even though many 180-600 owners achieve it.
For relative novices - the odds off good resolution improve significantly when everything is right - such as
1/ good light with good contrast
2/ a shutter speed at least twice the focal length - 1/1200 at 600mm - though not always possible.
This is where 10 fps or faster with the hope of at least 1 shot sharp can be useful.
Going back in better light etc if possible is often a better solution.
3/ small birds shorter than about 6 inches in length move very fast -
1/2400 may ideally be needed to limit loss of sharpness due to subject movement
4/ often overlooked by relative novices -
a subject with detail where AF has a good chance of being accurate
5/ good health and physical strength - at age just over 80 I cannot hand hold a 600 as steadily as I could when age 75.
Those fortunate enough to own a range of lenses, a good tripod and a resolution test target can easily establish what level of resolution is possible with their equipment.
Results at test sites I respect indicate for resolution nothing from Nikon beats the Plena at around f5.6-f8, and nothing in longer focal lengths beats the 400 f2.8 S at f5.6-11.
I cannot afford the 400 f2.8 - and at age over 80 even if I could afford it I could not carry it far.
VR in the 180-800 probably has slightly less capability than other S long focal length lenses - probably because of the lowish price point it does not support synchro-VR.
f6.3 is not an ideal starting point - and stopping down a little improves resolution on most lenses brings up shutter speed problems.
When I help other photographers with similar perceived problems at 1 to 1 level the problem is usually resolved showing them in good light with the right hand holding technique on a subject where AF should work well results are dramatically better.
If a lens does not have the resolution it should compared to other lenses it is easy to send it back with comparison photos with other lenses.
If a lens consistently mis-focusses by a mile I consider it naive to presume fine tune can help - because fine tune is for fine tune only and cannot adjust for consistent mis focus by a mile. Again it is easy to send it back accompanied by test shots using another lens.