Nikkor 50/1.8 Ai: Service

[Andreas Thaler]

Convinced that helicoids do not always have to be separated for cleaning and re-greasing, I got to work.

A Nikkor 50/1.8 Ai turned quite dry when focusing.

Some dust had also accumulated on the inner lenses over the years.

I wanted to remedy all of this.

Glow of dust in the LED light

Fortunately and unexpectedly, these three bayonet screws could be removed without any problems.

The bayonet screws on a Nikkor are often very hard to loosen because they are secured with adhesive.

See on topic:

Repair: Nikon Bayonet Screws (Video)

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Three small screws hold the back cover in place, one of which is longer than the others.

A mark for assembly later can't hurt.

Photos for orientation as to what needs to be aligned with what.

Using the spanner wrench, I take out the rear lens assembly.

It can be unscrewed after loosening.

The rear side of the panel is exposed.

Take care, that the aperture locking ball, which is spring driven, does not jump away when the aperture ring
is removed.

A sealed plastic bag comes in handy for this.

These two screws hold the aperture lever in the tube.

After loosening the aperture ring can be removed.

Ahh, there isn't a ball that is used to lock the aperture ring into place.

But rather a rocker that reaches into the recesses in the aperture ring.

 

[Andreas Thaler]

Removing the front lens unit.

Old grease and dirt on one of the two helicoids.

That has to go.

View into the tube from the front.

Mechanical degreasing

Preparing the shower with Zippo lighter fluid

In several passes I rinse the helicoids with lighter fluid and turn the focus ring from lock to lock several times.

The grease dilutes and the lighter fluid-oil mixture runs off or is dabbed off with a cotton swab.

The aperture register also comes into play when flushing.

I dry the tube with the hot air blower and move the aperture blades until they are dry and run smoothly.

Process temperature is 80 degrees Celsius (= 176 degree Fahrenheit), the air jet is weak.

It's clean here now

Apply Castrol LMX Li complex grease sparingly to the accessible part of the helicoids.

After turning it in and out several times, the focus ring runs smoothly.

The aperture ring is cleaned with Zippo, including the recesses for the rocker, where old grease is still found.

Then put some of the Castrol on here too.

Assembly

The rear lens assembly is back in place.

Lenses clear, focusing smooth again, nothing damaged.

Mission achieved

 

[Andreas Thaler]

Later, I took the focus ring off again to check whether the new lubrication was ok.

On this occasion I cleaned the ring with Sonax Profiline All-Purpose Cleaner Foam using a toothbrush.

Drying is enough and the engravings shine again.

The rubber grip ring is also fresh again

If you work with solvents, you should protect yourself.

But it's better not to look out the window like that

+++

All information provided without guarantee and use at your own risk.

 

[BrianShaw]

Excellent! Is it fair to assume the 1.4/50 is the same?

Is that Castrol grease a damping grease? If not, would you think “medium” damping grease appropriate? I have a tub of that from a tripod head overhaul… as well as a Nikkor that is starting to run dry again.

 

[Andreas Thaler]

Thank you

I'm not sure what you mean by "damping grease".

But here is information about LMX by Castrol:

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/B215DF5968A78AE680257796002FEFA4/$File/LMX%20GREASE.pdf

As for the Nikkor 50/1.4 Ai(-s), I think it has a different construction. No two Nikkors are the same

 

[Andreas Thaler]

Both lenses should be different:

Repair: Nikkor 50mm f/1.8 Ai

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Repair: Nikkor 50mm f/1.4 Ai-S

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[BrianShaw]

Damping greases not only lubricate but are used to adjust the feel of the helicoid. Motion control. I use NYE products as they are easily available.

Damping - Nye Lubricants

Widely used for electronic controls where they ensure smooth, quiet, controlled motion, and make very precise settings possible.

www.nyelubricants.com

 

[Andreas Thaler]

I have little experience with grease for lenses.

I'm happy with LMX, but I know that there are greases that make the helicoids spin softer or tighter.

 

[BrianShaw]

How does the LMX make the spin feel, light or heavier? I’m sure it’s smooth as silk in any case.

 

[jimjm]

Excellent tutorial! Thanks for posting this!

 

[Andreas Thaler]

Sorry, I didn't mention how I cleaned the lenses.

To clean, I use isopropyl alcohol, which I apply thinly with a cleaning swab or microfiber cloth. This removes greasy dirt easily, but streaks remain.

I remove the streaks with very little Aqua purificata on a microfiber cloth.

Beforehand, I always use a pointed probe to check whether the glass is scratch-resistant, which is usually the case.

I once ruined a Minolta MD 135/2.8 while cleaning because one of the front lenses is very sensitive to scratches. I learned from that.

 

[Andreas Thaler]

Excellent tutorial! Thanks for posting this!

Thank you, you are welcome

 

[Andreas Thaler]

How does the LMX make the spin feel, light or heavier? I’m sure it’s smooth as silk in any case.

I would say between light and heavy.

But definitely it is not the silk experience so highly demanded