Topic: Coating in bad condition

[jharr]

I just bought an early model Nikkor 50/1.4 non-ai to replace one that I dropped and lost infinity focus on. The replacement purchase was sort of a gamble on the bay as the pictures weren't very good and I couldn't see the condition of the glass. So it arrived and the front element is pretty messy. I don't think there are any bad scratches, but the coating seems to be damaged, like it looks dirty, but it isn't. I haven't taken any photos with this and my old lens had a rather significant spot on the front element coating that never had any effect on the pictures. So my question is, should I:
a) leave it as is?
b) try to uncoat the front element?
c) try to swap the front element of the old lens with that of the new?

Of course, if the first roll through looks good, then it's option (a), but otherwise what is the collective FW wisdom on this?

BTW, it was $42 incl s/h and included a PK-3 27.5 mm extension tube, so it was a pretty good deal.

[Francois]

Personally I've always been a fan of taking two to make one, so I'd swap the lenses.

I'm surprised that you lost infinity. This means that the entire barrel is either bent or that the hit was hard enough to make it skip the helicoid....

I had a Minolta lens that wouldn't reach infinity. It turns out the problem was at the back of the lens where there are two stops to control rotation and they were both out of shape.

If you choose to change the front element on the Nikkor, from memory it is held in place by a lateral set screw and a torqued retention ring on the front. So it should be an easy fix.

[jharr]

Personally I've always been a fan of taking two to make one, so I'd swap the lenses.

I'm surprised that you lost infinity. This means that the entire barrel is either bent or that the hit was hard enough to make it skip the helicoid....

Yeah, it skipped the helicoid. I got everything working normally again, but it just wouldn't focus in far enough to get there.

I had a Minolta lens that wouldn't reach infinity. It turns out the problem was at the back of the lens where there are two stops to control rotation and they were both out of shape.

If you choose to change the front element on the Nikkor, from memory it is held in place by a lateral set screw and a torqued retention ring on the front. So it should be an easy fix.

Unfortunately, neither of my lenses have the set screw arrangement, so I have to go in from the back which is considerably more complicated. That's why I would consider buffing the coating off of the front instead of completely disassembling both lenses. I could wind up with a couple of bookends.

[SLVR]

I wouldn't swap the front element unless you're prepared to swap ALL of the elements.

Im not sure about Nikon but Ive been told that leica specifically selects its elements in their lenses to compliment each other for best performance. Meaning that if you swap the front element, it may not "jive" well with the rest of the elements and may not give optimal results.

I had this on my Rigid summicron and I had it sent out to focal point lens in colorado. They took out the element, polished it and recoated it with modern coatings. The result is a wonderful lens. However the cost may not be worth it for you. I say that its probably more economical to take it to a serviceman who can swap over the elements from one to the other.

[Francois]

And since it's not a front focusing lens, fixing it means taking everything apart...

And removing the coating will give you that saving private ryan look... this combined with bleach bypass that is.
I know that WD-40 is said to remove the coating off many lenses... I wouldn't have the guts.
Or you could just use it as-is with a lens shade. This helps a lot since the front element damage is often less visible that the rear element.

Have you checked here http://forum.manualfocus.org/index.php
They have a bunch of user made instructions on how to fix lenses.

[02Pilot]

Not a rare or hideously expensive lens, right? If it were me, I'd go at the front element with Flitz metal polish on a cotton swab. It will take off some coatings (usually earlier single coating) but not others. It will definitely get other crud off, even incredibly persistent stuff. Do that a few times and see how it looks. It won't make it worse.

[jharr]

Not a rare or hideously expensive lens, right? If it were me, I'd go at the front element with Flitz metal polish on a cotton swab. It will take off some coatings (usually earlier single coating) but not others. It will definitely get other crud off, even incredibly persistent stuff. Do that a few times and see how it looks. It won't make it worse.

Yeah, "good" examples go for $80 - $150, but I am cheap. I thought about Flitz, but maybe even toothpaste would work? I don't want to make the glass hazy.

[Late Developer]

Some of this talk about abrasives and WD40 is making my toes curl.  Please - just buy another cheapo lens 

[jharr]

Some of this talk about abrasives and WD40 is making my toes curl.  Please - just buy another cheapo lens 

Oh, I imagine it's going to get much much worse. You may just want to pass on this thread if you are squeamish. 

[02Pilot]

There's a difference between Flitz, which is a chemical polish, and abrasives like toothpaste (or similar compounds - I'd use 3M Imperial Hand Glaze, made for auto paint, which uses a degrading abrasive). Another possibility in the latter category is original Bon-Ami, a powder made from eggshells, which also works wonders on windshields. I've found Flitz to be more effective overall than the abrasives, but it's hard to know for sure without seeing the lens in question.

[Late Developer]

Some of this talk about abrasives and WD40 is making my toes curl.  Please - just buy another cheapo lens 

Oh, I imagine it's going to get much much worse. You may just want to pass on this thread if you are squeamish. 

Many moons ago, a friend of mine decided it'd be a good idea to try to remove the coating from a seriously nice Minolta lens and ended up with what can only be described as a soft-focus lens.  It was horrible.  To be honest, I was convinced that leaving the lens as it was would have been the best idea as it was fine so long as not used directly into the sun.  I hope the remedial work does the trick.....

[02Pilot]

I've successfully polished a lot of lenses, including a few that were virtually opaque when I got them. Aside from potentially removing the coating, nothing I'm suggesting will harm the lens unless it's made of cheese.

[Late Developer]

I've successfully polished a lot of lenses, including a few that were virtually opaque when I got them. Aside from potentially removing the coating, nothing I'm suggesting will harm the lens unless it's made of cheese.

Great, and I'm not suggesting otherwise.  It's just the thought of it.  As I said earlier, I hope it all works out...

[Francois]

I've successfully polished a lot of lenses, including a few that were virtually opaque when I got them. Aside from potentially removing the coating, nothing I'm suggesting will harm the lens unless it's made of cheese.

Or plastic like some modern lenses... Synthetic glass is not always the toughest stuff...

[jharr]

Well, as bad as it looks, there doesn't seem to be any appreciable effect in the photos taken with this lens. I shot this roll of really really expired K-Mart slide film with it and aside from the graininess of the film itself, I can't tell that there is noticeable loss of contrast or any artifacts in the image. I took another roll with it today duplicating each shot with and without a lens hood, so that might give some side by side images to compare, but so far, I think I am satisfied with the images through this lens.


FTN-KMart-004 by James Harr, on Flickr

[02Pilot]

You'll have a better idea when you see what it does pointing toward a light source. It takes a lot of imperfections to affect shots without a significant light source, but direct light will scatter all over the place with fairly limited provocation.

[jharr]

The thing is, I don't really shoot into the light (Peter Gabriel reference). I most often shoot orthogonally to the light source. Sometimes the sun hits the front of my lens, as in this shot, but is not included in the shot. So I guess, considering my shooting style, the coating damage is sort of a non-issue.

Whale skull at Torrey Pines State Beach.


FTN-Prof-022 by James Harr, on Flickr

[Francois]

In that case, just use a lens shade and you'll be good for 99% of all scenes.

I'm thinking about something though... Putting a  multicoated UV filter on would pretty much "fix" the damaged coating on the lens.

[02Pilot]

In that case, just use a lens shade and you'll be good for 99% of all scenes.

I'm thinking about something though... Putting a  multicoated UV filter on would pretty much "fix" the damaged coating on the lens.

I don't think the filter idea would work in the way you describe. You're adding two air-glass surfaces to the light path, which on balance would likely end up reducing light transmission and introducing further possibilities for flare.

James, if you're not shooting into the light, you probably won't notice much effect, especially with a hood.

[Francois]

Well, UV filters don't gobble-up much light in the first place.
Then, since the filter I'm thinking about is multicoated, it should remove reflections on both sides (in between the lens and filter and in front of the filter), so the contrast reduction should be minimal.

But the drawback is that these coated filters are usually pretty expensive. I know I've never bought one and don't think I ever will.

The lens shade is a cheap and sure fire way to fix most of the problem.