Is it possible to have a lens recoated??

Started Jun 27, 2005 | Discussions
Daemeon Veteran Member • Posts: 3,132
Is it possible to have a lens recoated??

My lens doesn't need it, but I am genuinely curious. If something were to happen to the coating on your lens would it be possible to have Canon recoat the front element??

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--The artist formerly known as The Krakken

(unknown member) Senior Member • Posts: 2,268
Re: Is it possible to have a lens recoated??

I doubt you'd be willing to pay for re-coating that lens element. For the majority of lenses this is done on a "production line" of sorts. Any changes to the production flow are costly. Also, the multicoating isn't simply an application of "painted layers" which are removed easily. And they would need removing before new application. By far simpler to exchange that one suspect lens element for a new piece.

But to accurately answer your question - yes, it is surely possible. But at an astronomic price.
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Mike Baginy

MitchAlsup Veteran Member • Posts: 5,391
Agreed

mbaginy wrote:

But to accurately answer your question - yes, it is surely
possible. But at an astronomic price.

You need to recognize that these coatings are applied in a vaccum and are only fractions of a micron thick (dozens of atomic layers thick). The lens needs to be complete disassembled down to the lens elements. The elements need to be cleaned.

Most coatings do not have a slovent that does not also disolve the glass itself, and to remove old coatings requires repolishing the surface!?! a horribly expensive operation if you do not have the equiptment on line to perform said polishing.

Many coatings need to be applied with the glass at elivated temperatures (200dC) in hard vaccum (10* -7 Torr) and the equiptment to do this is very expensive.

Multilayer coatings are chosen based on the refractive index of the glass being coated, so a coating (set) for a crown glass is wholy unsuitable for a flint glass or a Flourite or SD or ED,...

Basically, you are working with tollerances on the order of 1/4 wave length of light--or about 0.5 microns! This is tough work--don't get your coatings damaged.
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Mitch

TimothySchlauch Contributing Member • Posts: 588
I Agree but.....

Hello eveyone....

I agree it would cost to much to recoat them, it's would be much cheaper to put new glass in it.

But then my thoughts turn to, just how good are the coatings in the first place. And jsut how much can they take, before they get messed up. Many times we hear, pros never even clean their lenses. So they don't mess up the glass, but it would seem silly to me.

If the coatings was so easy messed up, then why would the makers go through all that trouble to put them on. And giving that any pro should know, how to clean glass and not mess them up in the first place.

So how good are the coatings on the glass, it would seem that cleaning 1000's of times the right way of course. Should never mess them up, and that keeping them clean can only help them. As long as you don't scratch them, when you clean them and use coating safe clearner on them.

David I Hale Regular Member • Posts: 206
Re: Is it possible to have a lens recoated??

I agree it would be very costly to have it recoated, much simpler to just replace the front glass. Canon service probably does it a lot already due to lens drops breaking the front lens or them getting scratched.

Then again, I'm one of the fans that thinks it's just cheaper to replace a multicoated filter.. then you don't have to worry at all about the factory coatings.. That's why I use a filter, more for the lens surface protection than as a drop protector. So far I've never had to even clean the orginal front glass or touch it since I got any of mine, they get the filter minutes after coming out of the box.
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OP Daemeon Veteran Member • Posts: 3,132
Coating safe cleaner? n/t
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--The artist formerly known as The Krakken

TimothySchlauch Contributing Member • Posts: 588
Re: Coating safe cleaner? n/t

Yes coating safe cleaner, clearner or wipes that is safe to use on all lens coatings.
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T.A. Schlauch

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Chang Yeon Cho Regular Member • Posts: 297
Re: Is it possible to have a lens recoated??

Though the coatings are thin they are fused to the glass with molecular polarization in vaccum. So the coating compounds are fused at electron level. As good as (if not better) than being welded on. There is worry of "peeling" the coast. You could only lose it if you chip the lens. The mirrors go through the same process in the machine actualy. with silver compound. I learned this when I visited Guardian Glass, one of the largest manufacturerer of float glasses and also they do coating for mirror and optical application for electonics.

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Mike_V Senior Member • Posts: 1,496
Re: Is it possible to have a lens recoated??

Unless there is a fault with the coating it is unlikely to come off unless it scratched off.

Like when there is grit on the front element and it is rubbed with a lens cloth.

Anti-fog solutions that contain silicon can scratch off coatings also.

If the lens element is spherical it can be reground and re-coated easily.

This is quite common in the film industry. However it can be expensive and it may be cheaper to buy a replacment element rather than repair a damaged one.

Aspheric elements cannot be recoated easily.

Freddy Mercurio
Freddy Mercurio Contributing Member • Posts: 513
salt water

IF salt water spray is allowed to stay on a lens for a length of time can it damage the coating?
Dan

santa Veteran Member • Posts: 4,500
I've trashed filters

I know lenses are tougher than filters (or so I'm told) but I've badly scratched enough filters in spite of my care, in difficult outdoor situations, that I always use a filter. I remove it for flare-prone shots that are critical, but keep it on for day to day shooting in spite of the "anti-filter" arguments.

santa Veteran Member • Posts: 4,500
great question

no idea in spite of the obvious tendancy to say yes, but what seems intuitively obvious isn't always true...

Steve_Horn Senior Member • Posts: 1,568
Coating hardness

Mike_V wrote:

Unless there is a fault with the coating it is unlikely to come off

My spectacle lenses are made of plastic and have a non-reflective coating.

I wear them every day in all weathers, when they get dirty I wash them with soap and water.

I have had my current pair for about three years and the coatings are still fine.

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MitchAlsup Veteran Member • Posts: 5,391
Re: I Agree but.....

TimothySchlauch wrote:

If the coatings was so easy messed up, then why would the makers go
through all that trouble to put them on. And giving that any pro
should know, how to clean glass and not mess them up in the first
place.

Coatings reduce reflections (which cause ghosts, flair,...) good coatings reduce these effects more than simple coatings.

A single coat of magnesium Flouride will reduce the reflectivity of a typical crown glass from 4% to 0.5% in green and 0.9% at the blue end 1.1% in red. This kind of coating is about 100 times softer than the glass surface.

There are multilayer dielectric coatings deposited in high vaccum chambers with electron gun sputtering techniques that are almost as hard as the glass surfaces they protect.

The military has access* to very resistant dielectric coatings they use on their optics that are harrd enough to be casually cleaned in the field with a wipe of a dirty shirt removing highly abrasive sand. These coatings cost about $10 per square inch and have a failure rate of 3-4% per coating run. (Failures get send back to polishing). A set of these kinds of coating on the lens set of a 24-70 would cost about as much as a 24-70 actually retails for!!!! I happen to have several eyepieces with these kind of coatings, and they are really good--making the typical multilayer coatings look like amateur attempts.

So how good are the coatings on the glass, it would seem that
cleaning 1000's of times the right way of course. Should never mess
them up, and that keeping them clean can only help them. As long as
you don't scratch them, when you clean them and use coating safe
clearner on them.

Proper cleaning techniques include never getting lens so dirty that the optical surfaces need to be touched in the first place.
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Mitch

[ ] Only the military can afford the cost structure

Peru_Photog Contributing Member • Posts: 939
Curious...is this fact or a good guess? nt
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It's not just the photographer...it's the equipment too that CAN matter.

Curtis Leo Forum Member • Posts: 97
Re: Salt Water On Lens

Salt water is very nasty on any electronics. I scuba dive with my 300D and soon, the 1dMII. in a underwater housing.

I've gotten salt spray, drops on the lens and if you don't wipe it off quick, the water evaporates off, leaving hard salt crystals on the lens. Salt crystals can scratch however a wet wipe with clean it right off. Dont' worry about it unless you have sand on the lens.

Dale Josephson Regular Member • Posts: 271
Try cleaning with distilled water...

I would normally recomend de-ionized water but most don't have access to it. Just put a dampened tissue on the spot for a few moments and repest until its gone WITH OUT rubbing!
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In an ideal world, Liz Parker would exist

PalmsWestPhoto Forum Pro • Posts: 10,003
more expensive than new front element

recoating would cost more then simply replacing the front element. Most front elements do not cost that much to replace anyway

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Michael Salzlechner
http://www.PalmsWestPhoto.com

Dale Josephson Regular Member • Posts: 271
Not easily reground and polished...

One has to match the radius ( curve) to match the element's original. That's very costly for a single surface.... I know, I fabricate and supply military and and other precision optics.

Even on our lines, a coating mistake can take an inordinate amount of time to fix.

Some substrates can be stripped with acid but as someone else mentioned, some will disolve and therefore can't be chemically stripped.

For consumer optics it's far more cost effective to replace the element than to fix it.
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In an ideal world, Liz Parker would exist

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