Would you risk trying to clean this lens?

[IShootPeople]

Another question regarding cleaning...

I just recently acquired what has been my most desired lens lately - a Canon 18-200mm. I purchased it as used from Amazon. The ad stated that it was in good shape, and for the most part it is.

However, I have noticed a speck of some kind of dust/debris on the lens, under the top layer. I don't really think it is showing on pictures somehow, but it is quite bothersome and makes me nervous.

I found a "how-to" guide on cleaning lenses, but I'm rather scared to try it as I do not want to make it worse! Would any of you risk it by trying to clean it, or would you just let it be?

Here's the guide I found:
http://petapixel.com/2013/05/16/a-fe...lens-dustings/

[IShootPeople]

Forgot to include pictures. Not the greatest, as I used my cell phone camera, but they might give an idea.

[JR1]

NOT being rude but no one in their right mind will take a lens apart except a technician

[Kodiak]

Another question regarding cleaning… I don't really think it is showing on pictures somehow, but it is quite bothersome and makes me nervous.

Hello Kim,

What I see, from the posted pictures, is that that dust is not even on a lens but
sitting on a ring. As long as it is there… don't worry.

The difficulty in lens cleaning is not to remove dust but to succeed rebuilding
the lens without introducing new particles! I know a very qualified technician
that takes care of my gear and he told me that…

— IF lenses are better built to protect against dust penetration. —

So, if the performance is not affected, enjoy and wait & see!

[IShootPeople]

Well, I have been known to not be in my right mind at times...

But in all honestly, I had a feeling that it wasn't a bright idea, just wanted to confirm. I didn't want it to be anything worse. I can't tell if it's just dust or a fungus, so I'm a bit nervous. I've been looking forward to this lens for a while now and I'm kind of overprotective....

[IShootPeople]

That's what I was hoping!

I haven't had a chance to give it a thorough testing, but the few shots I took at the start did not seem to show any spots. Even if there are, I should be able to remove them in PP.

Thank you for the reassurance!

Hello Kim,

What I see, from the posted pictures, is that that dust is not even on a lens but
sitting on a ring. As long as it is there… don't worry.

The difficulty in lens cleaning is not to remove dust but to succeed rebuilding
the lens without introducing new particles! I know a very qualified technician
that takes care of my gear and he told me that…

— IF lenses are better built to protect against dust penetration. —

So, if the performance is not affected, enjoy and wait & see!

[JR1]

Well, I have been known to not be in my right mind at times...

But in all honestly, I had a feeling that it wasn't a bright idea, just wanted to confirm. I didn't want it to be anything worse. I can't tell if it's just dust or a fungus, so I'm a bit nervous. I've been looking forward to this lens for a while now and I'm kind of overprotective....

You obviously never bought lenses in the 60s when you got dust and bubbles in the glass

[ajohnw]

That may well be coating damage if it doesn't move around when the lens is shaken. That would put me of buying it to a certain extent because the reason for the whiteness may be caused by the usual levels of moisture in the atmosphere. Modern ED etc glasses can be very water sensitive. In the case of camera lenses these glasses are usually referred to as SD etc. They are good for photography in a rather odd way. Manufacturers had to add anti reflection coatings to protect them. Prior to their introduction just coating the surfaces that can be seen was common - the external lenses at the ends.

On the other hand it's not worth bothering about. The thing that counts with lenses is area and the area of the white dot is clearly one hell of a lot smaller than the entire lens. A maniac might put a blot of opaque black paint over it to stop it influencing the entire image but that sort of thing is more appropriate for larger faults such as cracks around the edge or chips.

The other problem is that when looking at thing like this the optics themselves can make it rather difficult to see where they actually are.

John
-

[Kodiak]

I can't tell if it's just dust or a fungus…

Use another lens as a loupe and look at it:

• dust is clearly recognizable, then see my previous post.
• if it's fluffy, starry or else, don't wait! If it is fungus, it
may attack the glass!

[Tringa]

I would let it be, Kim, especially as it is not showing up on your photos.

If the chance of the spot affecting photos really concerns you, try some test shots - plain light and dark walls in different lighting conditions and at different apertures, and some shots of plain sky, particularly some almost towards the light. To isolated the camera as much as possible the camera should be on a tripod and using mirror lock up.

However, if the spot shows up in such shots, it doesn't mean it will be noticeable in real world shots.

I'd just use the lens and if there is no effect then I'd forget about it. If the spot causes a noticeable effect then consider getting it fixed. Personally I would not try to repair a lens myself.

Dave

[ajohnw]

Use another lens as a loupe and look at it:

• dust is clearly recognizable, then see my previous post.
• if it's fluffy, starry or else, don't wait! If it is fungus, it
may attack the glass!

Glass eating fungus leave a sort of spider web type effect. I've seen more than enough of it on old microscope optics. White marks like this are very likely to be pin holes in the coating on special optical glasses. Best left alone and are unlikely to progress further at an alarming rate. Or send it away for repair and they may fit a new element. Dust internally will move around.

John
-

[ajohnw]

I would let it be, Kim, especially as it is not showing up on your photos.

If the chance of the spot affecting photos really concerns you, try some test shots - plain light and dark walls in different lighting conditions and at different apertures, and some shots of plain sky, particularly some almost towards the light. To isolated the camera as much as possible the camera should be on a tripod and using mirror lock up.

However, if the spot shows up in such shots, it doesn't mean it will be noticeable in real world shots.

I'd just use the lens and if there is no effect then I'd forget about it. If the spot causes a noticeable effect then consider getting it fixed. Personally I would not try to repair a lens myself.

Dave

Better still fit an old or unwanted filter on any lens and cut a small square of masking tape say 4 to 5mm square on a lens like this one and stick it anywhere you like on the filter and take some shots and see if you can spot the difference. There is one general position where you might at some aperture but even then maybe not..

John
-

[Glenn NK]

It is extremely difficult to make dust (spots) on a lens show up on an image:

http://www.lensrentals.com/blog/2011...e-of-lens-dust

http://www.lensrentals.com/blog/2008...ment-scratches

There is an old expression from the eighties(?) - "don't sweat the small stuff".

Dust is the small stuff.

[benm]

Since the dust is near the front of the lens I would not worry about it.

Check out this link showing sequential damage to a lens:
http://kurtmunger.com/dirty_lens_articleid35.html

[IShootPeople]

Thank you everyone! I appreciate the input, and the links with all the extra information. This is definitely the most I've spent on a lens thus far in my photography hobby, so I am a bit gun shy on making certain nothing happens!

[Eliseo]

In the olden days, i.e., '50s, air bubbles much bigger than your dust speck in the lens glass were common. I passed up buying a new Biotar lens because it looked like bad workmanship. The lens dealer in Germany said that the only effect I would notice would be in the Dmin, toe, the deep shadow area, a desirable trait in the days of very contrasty black-and-white films, specially when shooting available light. If its not near the focal plane, e.g., a filter behind the lens, I would not bother about it. It will not cast a shadow.

[rpcrowe]

I remember a camera repairman who had a junk aerial camera lens (which had a diameter of about eight inches) on his desk and used it as an ash tray. Even knowing the lens was junked, it still seemed strange to see somebody crush a cigarette against the front element of the lens.

The moral of this story - don't dismantle a lens unless you:

A) You know what you are doing

or

B) You smoke and are in dire need of an ash tray

[Mike Buckley]

This is just a quick reminder that the thread dates back to October 2014.

Welcome to CiC, Eliseo! It would be great if you would edit your profile to include your approximate location and your first name (perhaps Eliseo is your name) so they are displayed on the left side of your posts.

[jcuknz]

Despite this being a historical thread I will add my amusement when I read this and similar threads after I read the story [ not on CiC] of a lens gradually being demolished with a hammer or something and it was only at the very end that any effect was noticeable in the results....
I appreciate your concern at an expensive investment on your part but really I do not think you should have any concerns and most definitely you should not take the lens apart
I rarely clean any of my lenses because I was brought up in the old days of soft coatings on lenses and the comment that more lenses are ruined by cleaning than photographs by a bit of dirt on the lens. Unless of course you make a habit of photographing with the sun shining on the lens instead of having a lens hood or using your hand to shade the actual lens.