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I have noticed there are lots of spots on the outside of the 1st optical lens on my Ef-S 18-200mm lens. They are not scratches and look more like marks left by dried condensation or water droplets.

enter image description here

I have gone through YouTube and looked at various methods for cleaning but nothing seems to work. Do you have any ideas? Failing that I could send it to Canon but that costs £65 and it's not a particularly expensive lens so I'm a bit reluctant. Moreover, I don't even know if they could remove these spots.

Your advice is much appreciated.

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    It could be damage to the lens coating, if it won't come off with a microfiber cloth or similar. I'm not sure if anything can be done. There are quite a few existing questions about lens coatings.
    – Stuart F
    Oct 13 at 14:59
  • I removed a lot of my "dust" bits by removing the lens, and holding the lens upside down, using a squeeze blower over and over. Turned out the dots were indeed inside the lens.
    – Steve
    Oct 14 at 18:42
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They look as if some liquid splashed over it, so you need an alcohol-based cleaning solution. There are some premoistened Lens Cleaning Wipes on amazon. Read the reviews before buying a specific brand. Just be sure they can be used on coated lenses.

But wait for other responses, I am sure someone will tell you the specific type of alcohol needed.


Additional note. There are different types of microfibers. Use one specific for lenses, they are the ones really smooth in texture.

There are other types that have a towel look. Do not use those on a coated lens.

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    Re: microfibres, I'd recommend to use either the hooked 'towelling' type or those specifically made for lenses - like spectacles etc - but do not use the smooth ones designed for 'glass' as in household mirrors/windows. They will tear a coating to shreds. [Also, don't buy cheap ones, they not worth it & just don't work properly. If you want a brand recommendation for household rather than optics, get 'E-Cloth'] For optics buy one [& spray] from the nearest optician or camera shop. [My qualification for all this… I used to clean screens for a living; glass, coated & non-, some just plastic;)
    – Tetsujin
    Oct 13 at 15:52
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Use ROR lens cleaner, it's the best one I've found: https://www.amazon.co.uk/Lens-Filter-Cleaning-Solution-Spray/dp/B002MQ59ME and a proper camera lens cleaning cloth for anything like this. If that doesn't touch it then you may have permanently damaged the lens or coating.

I don't mean this to sound patronising, but the real answer to this, is don't let this ever happen. Every time I get myself a new lens, I also buy a cheap UV filter. This goes on immediately the lens comes out the packet, and rarely comes off (only for an occasional deep clean).

Your post is exactly why I do it. It's like insurance, for about £10 I protect the lens and if ever the filter gets damaged like this, I can swap it out for another £10. If a proper cleaning solution doesn't sort this out for you, I'm afraid it may be simply too late for this lens, in which case I'm sorry.

Here's a few tips which will help protect lenses. It's always worth spending a few quid to protect a lens worth several hundred pounds:

  • Ensure you get a cheap UV filter for every lens you buy.
  • Use a lens hood whenever using the lens (should come with lens).
  • Ensure the lens cap is clean, get a new one if not. Keep it on the lens all the time it's not used.
  • A proper camera case for your equipment is padded inside and will protect your lens.
  • Get a decent camera care kit and clean all exposed optics regularly.
  • If your lens isn't weather sealed, take it out in rain, fog, mist at your own risk!
  • Don't leave lenses in the sun or let them get too hot.

Good luck!

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Roger Cicala wrote a 2011 completely-over-the-top article on lens cleaning that describes all the gear and methods that lensrentals uses to clean lenses, lens hoods, and lens cases.

Typically, you start with least contact to most-contact methods, but what you're more worried about is whether the coating of the front element has been physically damaged or whether it's just dirt. If it's just dirt, start with a blower or brush to remove dust. And then proceed to contact methods. The two typical ones I use would be Zeiss lens wipes (I buy boxes of them from Wal-Mart), and a Lenspen.

While you can use a liquid cleaner and a microfiber cloth, the main issue tends to be any grit that might be caught in the cloth (or on the lenspen head) that could scratch your front element. The Zeiss wipes, being disposable and individually packaged eliminate that issue, and are good for travel or on-a-shoot cleaning. [Also cleaning your glasses as well as your front/back elements and viewfinder windows all in one go.]

The lenspen is the next most convenient, since it uses a dry carbon compound (kind of like toner powder) and has a brush on the back end. The only issues (aside from keeping the head clean) is that you occasionally have to "recharge" the head by twisting the cap while it's on the pen (why you'll often see posts on messageboards by folks complaining their pen stopped working after a few cleanings) and you may have to use a blower/brush to remove any cleaning compound residue.

If neither a wet cleaning or a lenspen can remove those marks, the it's likely the coatings on the front element are damaged, and you might need to get it replaced. And if the situation that damaged your lens is likely to occur again you may want to consider investing in some UV filters as physical protection that you can more easily swap out when damaged.

Some folks calculate replacing the front element as cheaper than going through bunches of UV filters, or hate possible flare from using a filter, and prefer to rely on a lens hood for front-element protection; others prefer using the UV filters and simply removing them if flare becomes an issue. It's a personal preference on how much they're willing to pay for UV filters, how frequently they need to be replaced, and how much of an image quality hit they introduce.

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