NikonGear'23
Gear Talk => What the Nerds Do => Topic started by: stenrasmussen on December 09, 2015, 22:26:14
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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.
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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.
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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.
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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.
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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.
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Sevice manual here:
http://allphotolenses.com/lenses/item/c_32.html (http://allphotolenses.com/lenses/item/c_32.html)
Looks complicated... :o
.pdf of user manuals of many other lenses and some service manuals here:
http://allphotolenses.com/pdf/c_18.html (http://allphotolenses.com/pdf/c_18.html)
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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.
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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 ;D
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Dr Lens II, don't you give up on me now :(
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What makes some members of the human kind wise is that they realise when it's time to give up.
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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 ;D
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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 (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.
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Two doctors at it ;)
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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 ?
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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!
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We indeed share the experience ....
I recently got a stack of Nikon bayonet mounts from my friendly Nikon repair tech, all of them being the torn-off rear part of 24-70 lenses. :D So indeed this works in practice and actually saves the unfortunate user from getting a damaged camera and associated huge repair bills.
Busy (and careless) press photographers enjoy the quick repair fix if you have NPS membership. My Nikon contacts tell me the repair by swapping the broken rear component by a factory spare can be easily done between the two halves of a football ('soccer' to some) match.
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Well, I just couldn't keep my hands off this lens. Disassembled it further this time and man...a previous owner has really tampered with it:
Chipped and scratched the rear side of the 4th lens group, bent the M/A focus brush, sanded(!) the inside and flanges of the rear fixed house (the part that sits just behind the zoom ring), marred screw heads, etc. Basically a wreck but I managed to get it back to kind of acceptable condition, i.e. smooth operation of zoom/focus rings, decentering less pronounced and autofocus less erratic.
Another weak design: The mainboards are secured with one screw only, increasing the chance of misalignment of the boards so one/both touches the rotating part of the SWM. If it touchdown happens a squeeky noise fills your ears.
Attached is a pic showing the chipped 4th lens group.
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This is the worst I have seen... ouch :o
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This is the worst I have seen... ouch :o
I guess some lens explorers are less cautious...l or should I say, "I-know-this-will-end-badly-but-what-the-hell"
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Some of the most fragile parts are the sliding contacts that are used for the read out of distance and focal length intervals, they are so tiny and thin... That's one of the reasons I try to stay away from messing with AF lenses. But how manage to do this internally to the glass, it must have been a war zone ::) :o ...
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The "repair man" probably used hammer and chisel or suchlike tools ...
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Here's the one of the two main boards. The gap towards the rotating black ring (to the upper left) is not large.
The brushes are fragile...and here's the bent example from said lens:
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I don't have a pic of the inside of the rear housing but I tell you...a desperate war must have played out there with tools to fit the "(un)intended" damage.
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Looks like the main board is not correctly mounted...
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Looks like the main board is not correctly mounted...
If you are looking at available space above the screw (to the right on the image) you are right. But the shown position is as far up as it goes.