Nikkor 20mm f2.8 Woes

ccbob · Jan 5, 2007

Well, for the third time since purchasing this lens (about 18 months ago), I am again faced with the stuck aperture issue.

Twice, under warranty, the lens was sent down to the El Segundo repair facility and twice it came back cleaned - only to last about 6 months before the aperture again sticks in the wide open position.

So, it looks like it needs to make another trip for another servicing - this time at my cost.

Has anyone else experienced repeating problems with this len's aperture blades? I've tried the 'store it vertically' trick, but apparently it made no difference in my case.

Robert Kerwin · Jan 5, 2007

I assume you're referring to the AF-D lens? I have the 20mm f/2.8D and have not had any problems whatsoever in 5+ years, but it's been a while since I've used it. I store it vertically, not intentionally, that's just the way it happens to sit in my camera bag.

If you've had this much trouble, perhaps you have a bad sample? I can't imagine that three trips to the shop in 18 months is par for the course.

Good luck, maybe the third time's the charm...

ccbob · Jan 5, 2007

Thanks, Robert.

Yes, I have the AF-D variant. From what I can gather from info found online, it seems that it has something to do with the lubricant that is applied to the blades. I guess in some samples, the lubricant seeps into places it shouldn't and thickens.

Oh well, at least it only cost me a handful of frames on my latest roll. I've been using the 35/f2 in many situations where I used to rely on the 20/f2.8.

mawz · Jan 5, 2007

ccbob: Aren't Nikon USA Lens warranties 5 years? I know they are here in Canada. I can't see why you'd be paying for the service, especially with 2 prior failures.

I'd be complaining strongly to Nikon about this.

ccbob · Jan 5, 2007

You may be right, I need to pull out the warranty paperwork. I was under the impression it was only a year - but I may be thinking of another product.

Thanks!

ccbob · Jan 5, 2007

mawz said:
ccbob: Aren't Nikon USA Lens warranties 5 years? I know they are here in Canada. I can't see why you'd be paying for the service, especially with 2 prior failures.

I'd be complaining strongly to Nikon about this.

Well, I dug out the warranty and you are correct, mawz. Nikon lists it as 1 year warranty + 4 years extended service contract.

This will take the sting out of my wallet, but probably won't lesson the disappointment in the reliability of this lens.

Thanks for the info.

Bob

erikg · Jan 5, 2007

I had this problem with an AF 28mm nikkor f2.8. Sent it back a number of times only to have the aperture gum up after a few months. I could no longer trust it so I gave it away, with a fair warning to the new owner. One of a number of issues that soured me on Nikon gear. Good luck with your lens, hope it gets resolved properly.

ccbob · Jan 5, 2007

erikg said:
I had this problem with an AF 28mm nikkor f2.8. Sent it back a number of times only to have the aperture gum up after a few months. I could no longer trust it so I gave it away, with a fair warning to the new owner. One of a number of issues that soured me on Nikon gear. Good luck with your lens, hope it gets resolved properly.

This is kinda what I'm afraid of. So far almost every six months or so, I seem to be having the same problem. Sad part is that I really do like this lens, but it looks like I may have to start giving some thought to replacing it with another ultra-wide.

Thanks for the feedback.

Canuck · Jan 5, 2007

ccbob said:
This is kinda what I'm afraid of. So far almost every six months or so, I seem to be having the same problem. Sad part is that I really do like this lens, but it looks like I may have to start giving some thought to replacing it with another ultra-wide.

Thanks for the feedback.

Not meaning to sound goofy (that's another matter for another time ) if the lens is out of warrantee, how about just sending it to a competent repair guy to use another lube other than the ones that the Nikon robots put into it? There must lots of other lubes that will work very well. Cheers!

ccbob · Jan 5, 2007

Canuck said:
Not meaning to sound goofy (that's another matter for another time ) if the lens is out of warrantee, how about just sending it to a competent repair guy to use another lube other than the ones that the Nikon robots put into it? There must lots of other lubes that will work very well. Cheers!

This is a valid approach for the future. But I believe for now that it is still covered under the extended warranty - so I'll let Nikon keep trying as long as it's free.

John Koehrer · Jan 5, 2007

ccbob,
Information only:
There's no lube applied to any portion of the aperture blade system.
There is lube in the focusing helical, and it has to be thin in order to autofocus.
What's happening is the lube is heated and then either migrates to the aperture system or evaporates and condenses on part of the system. Because of the surface tension on the blades or blade operating ring/housing there's not enough muscle in the system to move it.
What any technician will do is remove the blades & clean the blades/housing/ring reassemble & consider it fixed. Unless someone comes up with a lube that is of low viscocity that doesn't migrate this will continue to happen.

ccbob · Jan 5, 2007

John Koehrer said:
ccbob,
Information only:
There's no lube applied to any portion of the aperture blade system.
There is lube in the focusing helical, and it has to be thin in order to autofocus.
What's happening is the lube is heated and then either migrates to the aperture system or evaporates and condenses on part of the system. Because of the surface tension on the blades or blade operating ring/housing there's not enough muscle in the system to move it.
What any technician will do is remove the blades & clean the blades/housing/ring reassemble & consider it fixed. Unless someone comes up with a lube that is of low viscocity that doesn't migrate this will continue to happen.

Thanks for the detailed info, John!

One thing that still puzzles me though is why can't I change the aperture manually by rotating the ring? In my case, the ring will rotate freely and I can hear/feel it clicking at the marked f-stop detents, but the aperture itself remains wide open.

Bob

erikg · Jan 5, 2007

That is how it was expained to me, John. I had my lens cleaned by Nikon and later by a local repair shop that I trust. I was told that this can happen if the gear gets left in a hot car etc. which I would almost accept if it weren't for the fact that this lens lived a comfy life in a climate controlled Museum! No one had any answers for that so I just gave up. It's the only lens I've had that had this issue. Hope the lens in question has a better fate.

John Koehrer · Jan 6, 2007

ccbob,
The aperture won't close because the lube holds it in place in the housing.
The aperture ring has a tab that is used as a stop, when the camera stops the lens down, the blades are pulled to the stop by a spring. The spring doesn't have enough oomph to overcome the tension of the lube.

ccbob · Jan 6, 2007

John Koehrer said:
ccbob,
The aperture won't close because the lube holds it in place in the housing.
The aperture ring has a tab that is used as a stop, when the camera stops the lens down, the blades are pulled to the stop by a spring. The spring doesn't have enough oomph to overcome the tension of the lube.

John,
Thanks for the further clarification.

The lens is currently on its way to Nikon. Hopefully I won't be repeating this in another 6 months.

nyoung · Jan 7, 2007

Bob,
It may be too late, but if I were in your shoes I would attempt to invoke my state lemon law to get a replacement. Something in that lens is out of tolerance to alow the lube to leak out. I've been shooting nikons since the early 80's and I've owned the 20/2.8D for over 5 years - its always mounted on a body. I've never seen problems like you are seeing with any of my lenses. My bags often sit for weeks locked up in vehicles in the south and mountain west 0 to 140 or more degrees with no lube leakage or aperture hanging.

ccbob · Jan 7, 2007

nyoung said:
Bob,
It may be too late, but if I were in your shoes I would attempt to invoke my state lemon law to get a replacement. Something in that lens is out of tolerance to alow the lube to leak out. I've been shooting nikons since the early 80's and I've owned the 20/2.8D for over 5 years - its always mounted on a body. I've never seen problems like you are seeing with any of my lenses. My bags often sit for weeks locked up in vehicles in the south and mountain west 0 to 140 or more degrees with no lube leakage or aperture hanging.

I'm not sure that 3 instances in 18 months would meet the lemon-law criteria (not that I'm terribly up to date on such criteria anyway). I guess it's something that I can look into... guess I'm kinda hoping that Nikon, noticing that this is a recurring problem, will simply replace it themselves.

Mike Kovacs · Jan 8, 2007

When you send it back to Nikon, insist that they replace the lubrication on the helical. Often times, in the name of efficiency (cutting corners), repair techs will clean the aperture mechanism but leave the old helical lube in place.

The grease is separating into its native components (basically soap and oil), and the oil is migrating everywhere. The aperture blades are the most sensitive to the presence of oil but it will migrate anywhere it can, including onto the optics. That can cause fog, provide food for fungus, etc.

ccbob · Jan 8, 2007

Mike Kovacs said:
When you send it back to Nikon, insist that they replace the lubrication on the helical. Often times, in the name of efficiency (cutting corners), repair techs will clean the aperture mechanism but leave the old helical lube in place.

The grease is separating into its native components (basically soap and oil), and the oil is migrating everywhere. The aperture blades are the most sensitive to the presence of oil but it will migrate anywhere it can, including onto the optics. That can cause fog, provide food for fungus, etc.

Thanks, Mike.

I'll have to dig up an old repair statement and see what they've done in the past (assuming it's that detailed).

Nikkor 20mm f2.8 Woes

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