Strange issue - 2nd frame shot is darker - yet the same settings?

Hi all,

First post here. I seem to have an issue I cant a solution for...

Occasionally when Im shooting with my D800 and the Nikkor 70-200 lens the first frame looks correct and then the following 2nd 3rd 4th frames are noticeably darker? This happens when I shoot fast, as in 4/5 frames in one go. It also happens when I shoot in Continuous High / Low mode.

It only happens with the Nikkor 70-200 AF-S VR 2.8 - not with my 50mm 1.8 / 15mm 2.8 fisheye or 28-70mm 2.8

Its very odd! I noticed it happen about a year ago - and a few times since.

I did some tests - Shooting 1 frame at a time with a second gap at the same still subject and each shot was fine, as soon as I started to shoot a bit quicker this behavior happens. The first frame is fine and the rest in that burst are darker.

I checked the meta data and each is exactly the same? Heres 2 shots I did as a test out of my window.

Both fired in quick succession and exported with no changes. Both on the D800 / Nikkor 70-200mm. at 320th f4.5 ISO 500 at 200mm.

As you can see the second is a lot darker?!!!

Anyone have any ideas?!?!

Thanks

Mark

Sticky slow iris,although would that lead to over exposure ?

yeah, and wouldn't explain why its only on the 70-200 this is happening?

Lens problem will only occur in one lense. It is either the Iris or the CPU. If it is the Iris, then it is over shooting when actuated fast. In case each successive shot is darker, that is the problem. In any case, the lens needs servicing/adjustment.

Second shot appears to have deeper dof, which would indicate aperture change.

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