[MLonlooker]

Yes, Klaus's observations created a question here ... though -2.36 EV in the edges/corners is not huge huge .....

I can't remember have you tried another E mount Sony?


maybe you could post a quick Sony E mount thread on DP review to see if anybody else is scratching their heads about the issue .....

..... .... my thoughts are now that it is a rushed FW issue ... which maybe corrected with a later FW .... if not, it is difficult to see what you could do at your end to change it's behaviour ...

........ some things are just unfathomable .....

BTW, I dreamed last night that I lost my D500 while I was putting up plasterboard on a large river bridge, when I looked round someone had pinched it .... even sleeping offers no escape from photographic demons .... (true) ......... it's regular scenario, especially featuring my 600mm F4E) .......

[stoppingdown]

I tried with FredMiranda because I've some bad memories of DP review forums (too many fanboys). Of course in the end I'll write to Viltrox, but I'd like to collect some more info before.

Yes, at the moment I think of the FW too — maybe the correction profile?

For what concerns nightmares... LOL. In my previous Nikon life I owned an AF-S 300 ƒ/4: at the time I was mainly focused on wildlife, so it was my workhorse. I was so excited when I got it, it was the longer stuff with a good quality I could afford. It lasted I think less than two years, then all of a sudden electronics went dead. It was bought at the grey market and in Italy the dealer/repairer had (still has perhaps) a reputation of making your life impossible for supporting products not sold through them — which means extremely long repair time without any estimation of the delivery time. So I bought another copy. After three years it also started showing problems with the electronics, but it didn't go dead. Instead, very often it refused to auto-focus. I had to unmount and re-mount it, sometimes multiple times. Then he restarted working, but in the meantime I had usually the subject. I was never able to understand the problem (BTW, I stopped using it in 2015, the last Nikon system piece of equipment I used). I thought it was something like dirty contacts, actually cleaning them seemed to improve things; but a couple of years ago, when I finally sold all of my Nikon equipment, I discovered that in the meantime he was gone dead too. Anyway: for several years I had “nightmares” of being in wildlife hotspots, surrounded by birds (including those living in different parts of the world, and extinct ones) and at the moment of shooting the camera fell apart, or I dropped it, or all of a sudden I was in the middle of water that went inside the gear, etc... LOL!

[MLonlooker]

Hi stoppingdown,

  Regarding your Nikon contacts problem, I had the same issue especially when I went to sell my Nikon AF-S 500mm F4D ....... no AF at all, I cleaned the contacts with alcohol and it sort of improved, but would revert to not working reliably again. 
  As I was selling it, it had to work, I taped up the rear exit so as protect the optics and went about cleaning with a fine scotch-brite quite briskly until the contacts were shiny again ..... low and behold when I mounted the lens on the D750 it worked like new. 
  Alcohol cleans grease but does not touch micro corrosion, which is the problem, why Nikon don't gold-plate the contacts I'll never know? ..... a brisk clean wit a scotch-brite would have cured your two 300mm F4 lenses for sure.
   This corrosion issue is also what causes AF motors to squeak and eventually stop focusing, the stator has a crystal coating which can form a micro-corrosion in damp conditions .... if you go back and forth with the focus ring, it will start to function again, keep going and the micro-corrosion wears away and the lens focuses normally again.

Motto of the story is to keep your camera gear in dry conditions; no dampness, no corrosion!

[stoppingdown]

Interesting. I'll give it a try.

[MLonlooker]

Interesting. I'll give it a try.

  Let's hope I'm right in your case ...... give the contacts a really good scrub with a fine scotchbrite and good luck ......

[Klaus]

I've posted a couple of test shots here:

https://drive.google.com/file/d/1CU1AH4w...AMmT0/view

Both same speed (1/4000s) and aperture (ƒ/1.8), ISO 100, a6700, mechanical shutter and electronic shutter.
After these tests, things are even stranger: the dark banding at the lower side is not present with the electronic shutter... but it's at the upper border. In previous tests I didn't notice it.

I finally found these images ..... have you tried taking these images at a lower shutter speed to see if this changes the dark areas? 1/4000s may be the source of the issue ... just a thought!

This kind of vignetting is due to the shutter and has nothing to do with the lens.
Shoot below at 1/500 or slower, and you won't notice this anymore.

[stoppingdown]

Yes, I'm persuaded it's the shutter. But why there's no problem with other fast lenses and same very fast shutter speed?

[Klaus]

I've seen this with other fast lenses as well.

[MLonlooker]

I've seen this with other fast lenses as well.

    Well what is the cause of it then? ...... it seems mighty strange!

[Klaus]

Other than for 1st curtain sync, it's not clear to me.