Canon nFD 50 mm/1.8: Cleaning the lenses

[Andreas Thaler]

For this I follow Kenneth (mikeno62) on YouTube, who explains all the steps in an hour-long video:




I really like Kenneth's videos.

Not only is his productivity impressive - new videos on lens service are published regularly - but also the calmness with which he goes about his work

In two other videos about the Canon nFD 50/1.8, Kenneth focuses on cleaning the aperture blades and the focusing unit.

Can be found on his YouTube channel:

https://m.youtube.com/@mikeno62

---

The candidate

There is dust and a large piece of dirt on the front lenses that has been bothering me for 15 years

There is also dust on the rear lenses.

Overall, the contamination justifies the intervention, which is never without risk.

Since I'm working in the front, the lens sits on its back cap, which protects the projecting aperture lever and the rear lens.

The plastic decorative ring around the front lens cannot be unscrewed, but rather clipped in. Therefore it can be levered out. To protect the lens when the lever is in place, I cut a piece of a block of tough foam. It once came to me as part of a package. (Unfortunately, it left some greasy marks on the lens, but they were easy to remove later.)

With the screwdriver, it's easy to pry out without any roughness.

The ring is off.

Dirt from decades becomes visible.

It gets away with the bellows and the brush.

Three screws secure a ring that holds the front lens assembly.

Kenneth recommends marking the position of the ring and lens assembly for reassembly.

I follow this advice, although I suspect that the positions are not relevant here because the lenses are uniformly shaped. But better safe than sorry.

I make two marks with the marking pen (hard tungsten carbide tip).

Line upon line …

… aligned with the infinity marks.

This makes it clear where the lens unit and ring should point later.

I unscrew the screws and put them away.

All three are the same, so they don't have to be lined up to be returned.

This ring is also gone.

Be careful, the front lens unit is now no longer secured and may fall out when turning the lens over.

 

[Andreas Thaler]

I use the lens sucker to lift the unit out of the tube.

The convex front lens ...

... and a concave lens that completes the unit.

The unit consists of further optical elements.

Since I cannot see how to open the unit they remain out of reach for me.

The aperture blades are exposed.

No oiling is visible.

The focusing unit for close-up.

It is not possible to change the adjustment at this level of dismantling.

The contamination in the hard, focused LED light.

The lens unit is securely held during cleaning in a rubber cylinder for unscrewing decorative rings.

The - scratch-free - cleaning is carried out in the order bellows - brush - bellows - lens cleaning paper, but this ...

... definitely not dry, but soaked in surgical spirit. (Zippo lighter fluid should do the same good job.)

Clean in a spiral motion from the inside out.

Since this leaves a streak, I switch from paper to a cotton swab soaked in surgical spirit.

This works.

Same procedure for the other lens.

Now it's cleaner.

 

[Andreas Thaler]

Overview

Dirt is still visible on the inside of the tube.

Clean with isopropyl alcohol and cotton swab.

OK

The front lens unit is back in place - lifted using the lens sucker.

The two marking lines are aligned with the infinity mark.

Now it's time to screw on the retaining ring.

One screw is slightly rusted.

Pure Durgol descaling solution, scraping and rinsing in Aqua Purificata are the treatment.

I will dry the screw with the butane powered Dremel Versatip.

Since I don't want to take off my tight-fitting nitrile gloves - which are flammable - there are protective leather gloves over them. (I'm being overly cautious here as the nitrile gloves can handle quite a bit of heat).

The screw is now free of rust and dry.

All screws are back in place.

 

[Andreas Thaler]

Likewise the decorative ring, which I simply clip back in.

The front lens unit, now largely free of dust and dirt


+++

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

 

[Andreas Thaler]

I will clean the rear lenses later.

Another item on my to-do list.

 

[forest bagger]

Hello Andreas,

I wish you a relaxful second christmas day.

I will clean the rear lenses later

Ok, don't hurry!
But in the first posting you wrote

There is dust and a large piece of dirt on the front lenses that has been bothering me for 15 years

I've seen some minor dust particles, but where was this large piece of dirt?

 

[Andreas Thaler]

Conclusion

• Thanks to preparation with Kenneth’s video, there were no unpleasant surprises. The most unpleasant thing would have been adjusting the infinity adjustment and then resetting it. Tedious, and I wanted to avoid that at all costs.
• The plastic decorative ring shows how Canon made its New FD series lighter. The era of the chrome ring and heavy metal design was over.
• I would also like to clean the other lenses in the front optical unit, there is some haze. But unlike Kenneth, I couldn't crack this nut. Maybe my version differs from his.
• Surgical spirit evaporates, applied here with a cotton swab, without leaving any residue. No re-polishing necessary, which protects the lenses
• I have now developed the habit of protecting myself from solvent fumes, heat and mechanical accidents. It's an extra effort with a mask, protective goggles and double gloves, but it keeps me healthy. I can only recommend this, especially if, like me, you sit at workbenches nearly every day.

 

[Andreas Thaler]

Hello Andreas,

I wish you a relaxful second christmas day.
Ok, don't hurry!

Thanks to you too!

This is a project I did a few months ago.

But in the first posting you wrote
I've seen some minor dust particles, but where was this large piece of dirt?

Unfortunately this cannot be seen in the photo. It was a small piece of metal foil or something similar. I don't think that's from the lens.

 

[Andreas Thaler]

I'm currently going through the open projects in my repair log.

Here is one of them, the rear lenses of the nFD 50/1.8 are still waiting to be cleaned.

It will start soon

 

[4season]

I'm currently going through the open projects in my repair log.

Here is one of them, the rear lenses of the nFD 50/1.8 are still waiting to be cleaned.

It will start soon

I got my 50/1.8 nFD for free because someone incorrectly reassembled the rear of the lens, and it took me awhile to figure out how to do it correctly. Good optics, but mechanically, I found it a bit complicated.

 

[Andreas Thaler]

I got my 50/1.8 nFD for free because someone incorrectly reassembled the rear of the lens, and it took me awhile to figure out how to do it correctly. Good optics, but mechanically, I found it a bit complicated.

The New FD System is probably the most technically sophisticated among the SLRs.

 

[forest bagger]

The New FD System is probably the most technically sophisticated among the SLRs.

That's true, Andreas.
It is stressful to dismount the bayonet, and even more stressful to remount it correctly.

 

[Andreas Thaler]

That's true, Andreas.
It is stressful to dismount the bayonet, and even more stressful to remount it correctly.

I hope I can get the rear lenses out without having to remove the bayonet. But that is interesting too.

 

[Andreas Thaler]

I hope I can get the rear lenses out without having to remove the bayonet. But that is interesting too.

Oh dear, two thirds of Kenneth's video above is about the rear part and the bayonet has to come off.

I'd better start early in the morning

 

[forest bagger]

I hope I can get the rear lenses out without having to remove the bayonet.

I'd try to remove the rear lens with a rubber block without removing the bayonet.
But if your specimen is built as in Kenneth's video (fixation of the rear lesens not with an screwed on aluminum ring but with this click on plastic ring) that won't work...

 

[4season]

Whenever I get frustrated working on a camera and lens, I think of how trained factory workers likely were accomplishing the tasks in minutes, or even seconds - and I try to figure out how they might have accomplished it! I don't recall reassembling nFD being difficult, just different from anything else that I had seen. I spent extra time learning how it worked, and spotting potential problem areas.

 

[Laurent]

Hi @Andreas Thaler . Nice to see you're getting back to this lens.

I made an attempt some weeks ago, on a lens that had fungus and I bought for cheap as a parts donor. I was able to open the rear doublet, but this was done with brute force and somewhat damaged one of the lenses.

Since the lenses are attached together with a plastic housing, I decided I'd try to drill holes in it (first attempt was to remove the "rivets" that can be see in the image above. Alas, they serve no mechanical purpose and maybe plastic injection remains).

The hole position is somewhat delicate, as it is needed to "land" between the two lenses.

I the used the hole to insert a prying tool and force the lens out of its place...

My prying tool is a dentist's tool, and the pressure on the lens damaged the surface.

Next time, if I have the opportunity, I'd like to try using a fluid under pressure to "eject" the lens, since the coupling is so tight. This would require a coupling gizmo to inject the fluid (air would be preferred), but may reserve good results.

 

[Andreas Thaler]

Hi @Andreas Thaler . Nice to see you're getting back to this lens.

I made an attempt some weeks ago, on a lens that had fungus and I bought for cheap as a parts donor. I was able to open the rear doublet, but this was done with brute force and somewhat damaged one of the lenses.

View attachment 373692

Since the lenses are attached together with a plastic housing, I decided I'd try to drill holes in it (first attempt was to remove the "rivets" that can be see in the image above. Alas, they serve no mechanical purpose and maybe plastic injection remains).

View attachment 373693

The hole position is somewhat delicate, as it is needed to "land" between the two lenses.

View attachment 373694

I the used the hole to insert a prying tool and force the lens out of its place...

View attachment 373695

My prying tool is a dentist's tool, and the pressure on the lens damaged the surface.

Next time, if I have the opportunity, I'd like to try using a fluid under pressure to "eject" the lens, since the coupling is so tight. This would require a coupling gizmo to inject the fluid (air would be preferred), but may reserve good results.

Thanks for the interesting information!

This lens is not easy to service and is probably not even designed for that.

The cheap kit lens for nFD

 

[forest bagger]

I don't recall reassembling nFD being difficult, just different from anything else that I had seen.

Well, difficult may be the wrong word.
If you know how to do it, removing the entire bayonet is'nt difficult at all. The reassembling, if you know which step to take one after the other, not much difficult also.
Burt if you have to disassemble the mechanics completely, it's getting worse...

 

[forest bagger]

This lens is not easy to service and is probably not even designed for that.

That is true. Even nowadays many lens groups are cold welded in a plastic housing.

My way to release the outer lens is to cut the plastic rim off that holds the lens.

 

[Andreas Thaler]

My way to release the outer lens is to cut the plastic rim off that holds the lens.

I would be concerned that I would no longer be able to put the lenses together correctly afterwards?

 

[Andreas Thaler]

Well, difficult may be the wrong word.
If you know how to do it, removing the entire bayonet is'nt difficult at all. The reassembling, if you know which step to take one after the other, not much difficult also.
Burt if you have to disassemble the mechanics completely, it's getting worse...

I will start working without any further preparation, it is good for the learning process. I will take this 50/1.8 as a practice project

 

[forest bagger]

I would be concerned that I would no longer be able to put the lenses together correctly afterwards?

You remove only the thin rim (in German: die Bördelung) of the plastic housing, than you can pull the lens out.
For reassembling push the lens in and fix it by some glue applied to the plastic housing instead of the missing rim.

 

[Laurent]

I started to wonder this night how hard it would be to replace the plastic rim by an aluminium one made on the lathe? I'll have to put my son on this project.

Also, a 3D printed rim could be a viable option! May even be very simple, as cutting the existing one in two would make a perfect reference...

 

[Andreas Thaler]

You remove only the thin rim (in German: die Bördelung) of the plastic housing, than you can pull the lens out.
For reassembling push the lens in and fix it by some glue applied to the plastic housing instead of the missing rim.

Maybe this also works with the Olympus counterpart?

Olympus Zuiko Auto-S 50/1.8: Front lens group cannot be separated

A 50/1.8 Zuiko, heavily molded, was quickly disassembled: The rear lens group consists of two lenses lying one on top of the other that are easy to clean: The unpleasant surprise comes from the front. The front lens group forms an optical unit - literally: The fungus sits between...

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