Nikkor P 105mm f2.5, seriall number434039

newcan1 · Jul 4, 2013

I just had this lens Ai'd and, testing it out, I find it to be quite soft at full aperture. The chap who Ai'd it did note to me that the lens rattles a bit (this was so before I shipped it to him). I decided to Ai it anyway.

If I shake the lens gently, it rattles slightly, and if I hold a tissue gently against the rear element and shake it, there is no rattle.

Thus the rear element would seem to be slightly loose, and I wonder if this affects image quality.

Anyone have any idea how to tighten the rear element of this lens?

It's not a bad lens, but I was expecting a bit more...

BMbikerider · Jul 4, 2013

There should be an annular ring with two or more slots in it and this will tighten the pressure on the rear element. It would be far better to have a technician do the work because if you don't have the correct tool it would be easy for what you are using to slip and seriously mark the rear element.

newcan1 · Jul 4, 2013

BMbikerider, thanks for the info. I can't see anything, is it possible that the lens mounting ring first need to be removed?

I do have a number of small camera/lens repair tools so am willing to give this a try.

BMbikerider · Jul 4, 2013

I have the later 105 lens (AIS) and there is a ring with 4 slots each at 90 degrees to each other. There obviously has been a change with the later lens which incidentally is about my sharpest optic of the bunch.

newcan1 · Jul 4, 2013

Yes mine's a non Ai version, and the back is kind of closed off, I suspect that if I remove the mounting ring, all will be revealed.

JLP · Jul 4, 2013

There's a big difference between the early Sonnar version you have and the newer Double Gauss especially on the rear element.
I think as suggested it would be better to return the lens and get it proper assembled.

newcan1 · Jul 4, 2013

Not an option - I have owned it for years and paying someone to fix it would cost more than it is worth. It's OK as is - if I can't tighten the rear lens, I'll just live with it.

damonff · Jul 4, 2013

I have the same lens, serial 408049. It is sharp all the way through. Yours has a problem for sure.

clayne · Jul 5, 2013

newcan1 said:
Not an option - I have owned it for years and paying someone to fix it would cost more than it is worth. It's OK as is - if I can't tighten the rear lens, I'll just live with it.

Lens spanner is less than 30$ at micro-tools. Since you don't have much to lose you can dig into it. Honestly just tightening down the rear retaining ring for the last element is a 2 minute job provided its accessible. If it requires removing the rear cover well that's gonna be more work but it isn't going to require cracking open all the elements or anything.

This lens should be sharp.

newcan1 · Jul 5, 2013

Well that was easy. I took off the mounting ring, and the rear element was set in a metal cylinder that just screwed/unscrewed. So I hand tightened it. If I had a rubber grip of some sort, maybe I could have tightened it a bit more.

The rattle is gone and the lens is about as sharp at 2.8 as when it is stopped down to f8. It compares in sharpness to my Nikkor 80-200 f4 when I set that at 105mm. My tests were just visual, using my D200. Film tests may be more revealing, because of the resolution limitations of the D200's 10MP cropped image sensor. I'll take the lens for a spin next time I go out with my F100.

I may try later to tighten the rear element just a bit more but it seems pretty good right now. And for once, a 15 minute easy fix!

E. von Hoegh · Jul 5, 2013

newcan1 said:
I just had this lens Ai'd and, testing it out, I find it to be quite soft at full aperture. The chap who Ai'd it did note to me that the lens rattles a bit (this was so before I shipped it to him). I decided to Ai it anyway.

If I shake the lens gently, it rattles slightly, and if I hold a tissue gently against the rear element and shake it, there is no rattle.

Thus the rear element would seem to be slightly loose, and I wonder if this affects image quality.

Anyone have any idea how to tighten the rear element of this lens?

It's not a bad lens, but I was expecting a bit more...

Ya think??

This is a world class lens. Yours needs work.

newcan1 · Jul 5, 2013

No longer. I fixed it. Piece of cake.

E. von Hoegh · Jul 5, 2013

newcan1 said:
No longer. I fixed it. Piece of cake.

These 105s really are great lenses - I'm glad it was someting as simple as it was.

Richard S. (rich815) · Jul 5, 2013

That's good news. My 105/2.5 is indeed one of my favorite portrait lenses. Love the character.

clayne · Jul 5, 2013

Great to hear you fixed it. BTW was it suffering sharpness wide open at specific focusing distances? The rear cell must have totally came loose for significant rattling to be heard. Additionally, and depending on lens design, a slight shift of the rear group away from the front group usually just results in a nominal change of focal length that tends to be compensated for when you check focus through the viewfinder. This is why it's not strictly important that the tightening of the real group isn't exactly as it was at the factory - as focusing shifts the front away from the rear anyway. That's why I ask if this was only present at the limits of focus or if the rear group was completely unthreaded. If its the latter I'm surprised you got sharp images at f8.

E. von Hoegh · Jul 5, 2013

clayne said:
Great to hear you fixed it. BTW was it suffering sharpness wide open at specific focusing distances? The rear cell must have totally came loose for significant rattling to be heard. Additionally, and depending on lens design, a slight shift of the rear group away from the front group usually just results in a nominal change of focal length that tends to be compensated for when you check focus through the viewfinder. This is why it's not strictly important that the tightening of the real group isn't exactly as it was at the factory - as focusing shifts the front away from the rear anyway. That's why I ask if this was only present at the limits of focus or if the rear group was completely unthreaded. If its the latter I'm surprised you got sharp images at f8.

No it does not. The entire optical part of the lens moves forward in the helicoid mount.

clayne · Jul 5, 2013

E. von Hoegh said:
No it does not. The entire optical part of the lens moves forward in the helicoid mount.

Whoops, sorry my bad you're completely correct. Not enough coffee yet. What I meant is that ultimately a small shift in the rear shouldn't result in massive offness (subject to lens design of course) but a change in some optical aspect that usually ends up being compensated for by literally focusing the lens.

newcan1 · Jul 5, 2013

Well to answer some questions, what I did was photograph a gallon plastic weed killer bottle that was about 45 feet away at the bottom of the yard. The bottle was a good subject as it has writing on it. My initial tests showed it to be a bit fuzzy at full aperture, with improvement with the lens shut down. On re-reviewing, it looks like the ground immediately behind it was sharper, leading me to wonder if the rattling rear element caused some erraticness in the precise plain of focus. Now the image is much sharper and compares with images shot with other Nikon lenses that I have (80-200 f4 and 35-135 f3.5/4.5). With none of the lenses is the small writing on the bottle legible, but the images with each lens are about as sharp as each other. Again, the test was done on an oldish digital camera (D200) which also introduces some limitations. My 35-135 produces razor sharp analog 8X10s so I am sure the 105 will now too.

The rattle was not significant, and the tightening involved an almost imperceptible turn of the element, but it makes quite a difference.

clayne · Jul 5, 2013

I'm surprised that an almost imperceptible turn of the rear element previously had audible rattling honestly. I'm also surprised that what you saw in the viewfinder, focus wise, resulted in back focus in the final image but then again this was 45' away. Anyway I'm glad you got it fixed.

Christiaan Phleger · Jul 6, 2013

That rear set of element may just need a bit of torque. Lots of old ones do.

E. von Hoegh · Jul 6, 2013

clayne said:
Whoops, sorry my bad you're completely correct. Not enough coffee yet. What I meant is that ultimately a small shift in the rear shouldn't result in massive offness (subject to lens design of course) but a change in some optical aspect that usually ends up being compensated for by literally focusing the lens.

Well, that depends upon the lens type, as you said. This is a Sonnar clone, and a telephoto design to boot - and if it behaves like the Tessar it was drived from, a tiny error in spacing will completely spoil the definition. Some lenses such as the Plasmat type are far less critical of spacing, say a few percent of the focal length - but the Plasmat's immediate ancestor the Dagor is very critical regarding spacing. The shorter the focal length, the smaller the errors which can be tolerated regardless of design. An error of .001" spoiling the performance is not uncommon with certain types.

clayne · Jul 7, 2013

E. von Hoegh said:
Well, that depends upon the lens type, as you said. This is a Sonnar clone, and a telephoto design to boot - and if it behaves like the Tessar it was drived from, a tiny error in spacing will completely spoil the definition. Some lenses such as the Plasmat type are far less critical of spacing, say a few percent of the focal length - but the Plasmat's immediate ancestor the Dagor is very critical regarding spacing. The shorter the focal length, the smaller the errors which can be tolerated regardless of design. An error of .001" spoiling the performance is not uncommon with certain types.

I don't disagree, but these lenses weren't exactly hand-assembled and individually checked when produced either...

E. von Hoegh · Jul 8, 2013

clayne said:
I don't disagree, but these lenses weren't exactly hand-assembled and individually checked when produced either...

How on earth were they assembled then?

It would seem that the OP's experience goes a long way to verify what I said, which by the way was not an opinion but based upon experience.
As far as whether or not Nikon performed optical testing on every single lens, the performance of these now 40~ year old optics suggests that whatever they did, and however they did it, the results were and are superb.

j-dogg · Jul 10, 2013

BMbikerider said:
I have the later 105 lens (AIS) and there is a ring with 4 slots each at 90 degrees to each other. There obviously has been a change with the later lens which incidentally is about my sharpest optic of the bunch.

I second this

Even wide open it's up there with my new Canon L telephoto glass

I have the very early silvernose NKK version with 6 blade aperture and single-coat glass and I liked it so much it made me convert my 5D to hybrid (split-image focus screen, lens adapter) so I could use it on d*****l.

My only complaint is the filter threads are a very soft metal I bent mine just setting it on the ground and filters are difficult to mount, I remedied this by smashing an old scratched UV and mounting the ring on the end of the lens

Very good lens, I was actually thinking of the Canon 100/2 but after shooting this on film and on d*****l I'm sold on the 105

semi-ambivalent · Jul 11, 2013

I have a 105 P, 126xxx, and it's pretty sweet. Designed as a short telephoto, Nikon changed the formula to the gauss when they became aware people were using it for close range portraits. The newer design is better close up and even manages to improve on performance at distance, if that was even possible. Mine is damn near equivalent to my AiS, and only when pixel peeping or with really big enlargements; like 30x.

An epoch ago the man at the traveling Nikon School told me Nikon matched lens elements to the entire assembly, letting a weak element here compensate for a strong element there. That was why, if you sent a lens to Nikon to have a front element replaced (and they did that back then), it was so expensive. They'd have to find a match for that specific lens element, or grind one.

Enjoy it. If there is such a thing as the singular Nikkor classic the 105 is probably it.

s-a

Nikkor P 105mm f2.5, seriall number434039

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