AF-S Nikkor 24-70/2.8: impact injury

[stenrasmussen]

So I have this lens that's taken a hit in the front. Previous owner glued up the broken filter threaded front but that was not it. The lens suffers from some kind of lens misalignment. I took off a couple of the front elements to see if the issue was there. Nope. I did find an odd hex-headed screw in there demonstrating that someone had tried a repair. Not was the head wrong, the threads were of the wrong sort as well. I found a better match in my selection of lens screws but not the exact right one. After reassmbly the lens i still soft on the left side so another opearion is needed. This time I'll attack the rear end.

[Bjørn Rørslett]

Sten: with a complex lens such as this you need to be extremely careful. The problem might be misaligned internal elements and that requires an optical bench to adjust. You stand the risk of making the lens worse. Give it to a qualified repair shop.

[stenrasmussen]

I know Bjørn. I won't attempt to get further in than the "easy" rear-most elements. The lens was offered to me for basically a song but I haven't decided to take it or not.

[bobfriedman]

the 24-70/2.8 AFS has also had a history of the screws loosening on the helicoid disabling the zoom... new 80-400 as well.

[Bjørn Rørslett]

Be aware that this lens, like other pro-calibre Nikkors, has a special construction in the rear that is designed to break away if the lens is impacted.

[Øivind Tøien]

Sevice manual here:
http://allphotolenses.com/lenses/item/c_32.html
Looks complicated...   

.pdf of user manuals of many other lenses and some service manuals here:
http://allphotolenses.com/pdf/c_18.html

[charlie]

A few years ago my 24-70 was attached to my D700 and they fell a short distance, about a foot or so, on to a concrete floor. It landed on the lens cap if I remember correctly. There was zero visual damage but the impact made the zoom helicoid bind. $300 or so to repair at Nikon's service center.

[stenrasmussen]

I talked to the Nikon repair man and he told me that when things like these happen it is the inner lens group that is replaced with a new one from Nikon.
Nothing I can do to compete so the lens will most likely have an afterlife as a spare parts candidate. The cost to fix this is half that of a new lens.
Oh well, tis was fun while it lasted 

[Jakov Minić]

Dr Lens II, don't you give up on me now 

[Bjørn Rørslett]

What makes some members of the human kind wise is that they realise when it's time to give up.

[stenrasmussen]

The lens is now back with my dealer and they will put it up for sale at a ridiculous price.
To make sure I have something to do they handed over a Siggy 105 macro of some kind.
Drawback: I feel like being pulled over to Voldemort's side...tis a Canon mount   

[Erik Lund]

We successfully repaired this on a lens Jakov had in his possession...
A little late on the heads up I know...
It's pretty straight forward to get it apart as long as you remember to remove the sliding contacts at the correct point...
Heres a video from the local shop doing the repair as well
https://www.youtube.com/watch?v=MwsGYvHGcDg
At 7:50 he is at the problem, the zoom screws that act as guides, they don't 'come loose' the loosen when you hit the lens...
The one we worked on had to have some major work to the front optical cell to get it to slide properly again.

Worked fine...

The 28-70 AFS 2.8 was a stronger internal design and the hood a little stronger, I managed to hit the zoom ring really hard and the aluminium got deformed, but works again now as well.

[Jakov Minić]

Two doctors at it 

[charlie]

Thanks for sharing that link, Erik.

It actually didn't look to difficult to make that particular repair given one has the right screwdrivers and tools. He (mikeno62) has another video where he lubes the zoom through the front of the lens which didn't look to difficult either. I like suction cup he used to remove the front element.

My 24-70 sometimes has a slight rough feel when zooming from 70 to 24, if it gets worse I might look into these repairs myself.
What sort of grease is recommend for lubing the zoom mechanism on such a lens, helical #10 ?

[enough]

Be aware that this lens, like other pro-calibre Nikkors, has a special construction in the rear that is designed to break away if the lens is impacted.

And from experience I can confirm that it works as designed!