Question about Canon EF 75-300mm f/4-5.6 II Lens

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Fungus canon 75-300 ultrasonic rear lens

How to disassemble

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If the lens has fungus It'll need to be cleaned professionally.

Posted on Sep 02, 2016


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Posted on Jan 02, 2017

Rick Riggins
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SOURCE: how can I repair my 35-135mm ultrasonic canon lens

Focus issues are quite common in lenses these days. This will require disasembly to trouble shoot and repair and can be done fairly inexpensively. However, it's not really a user serviceable problem and should be done by a qualified service technician.

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Posted on Sep 09, 2011

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How to clean sigma 500mm 4.5 fungus

Do you have a lens collimator and other gear needed to ensure proper alignment when reassembling the lens? If not, try this. Put the lens inside a window where it receives directly sunlight. Yes, you'll probably have to move the lens every few hours to it continues to receive direct sunlight. Do this for a day or two. If the fungus persists then take the lens to a reputable camera shop and have a properly trained and equipped professional clean the lens.

Jul 20, 2014 | Sigma Cameras

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How do i get rid of mild fungus in Sony Hybrid handy cam DCR-SR65 lens

Bring it to the camera photo repair shop where they can disassemble, clean your lens. They have the tools and cleaning solution to get rid of lens fungus. I hope my advice give you some idea.

Mar 18, 2011 | Sony DCR-DVD755/E DVD Camcorder

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My lens inside growing some fungus. Please tell me out clean that at home.( I am Fiji here don’t have technician for repair)

Sorry, but there's no way you can disassemble the lens and get it back together so that it will work. This takes special tools and lens alignment equipment.

Dec 01, 2010 | Canon Rebel XT / EOS 350D Digital Camera

1 Answer

Fungus (oil spray/mist?) on inner lens surfaces - how to disassemble and clean a Canon 75-300mm EF AF lens? A skeleton picture would also be helpful. Thanks, Tom.

Okay. I just wanted to scare you away from ruining a perfectly good (or nearly so) lens, but a learning project is a different matter. And a lens collimator is not that hard to build. One source is the book "Camera Maintenance & Repair" by Thomas Tomosy. I'm sure a quick Google search would show even more.

I did the same thing myself decades ago, taking apart a damaged zoom lens. Unfortunately, I never got it working properly again :-( But it was an educational experience, even though I didn't have a lens collimator...

Nov 13, 2010 | Canon EF 75-300mm Lens

1 Answer


It is lens fungus and you're correct in your assumption that it's uneconomical to professionally repair on your lenses. But it need to be pretty bad before it affects image quality so don't junk them just yet.

Some types of lens fungus can be killed simply by leaving the lens out in sunlight, but I'd suggest that it's better to leave them exposed to the indirect sunlight on a bright overcast day to prevent any chance of sharply focussed light burning the inside of the lens. Killing the fungus won't remove the dead stuff but it prevents the problem getting worse.

May 29, 2010 | Quantaray 100-300mm F4.5-6.7 Zoom Lens for...

1 Answer

Hi - I have an Olympus OM Zuiko 8mm f2.8 which I'd like to take the rear lens elements out to clean some fungus off them. Its not a bad infection and I have ammonia to clean them with. How do I get access...

Best of luck as good quality camera lenses are assembled in totally dust free environments. Even if you are to get the lens fully apart, the fungus may be not on but between one of the glass elements ( some are compound lens elements made of more than one piece of glass). You cannot disassemble a compound lens glass - a hammer works tho!. Not sure about ammonia but bleach is a good fungus/bug remover - but any chemical may well affect any lens coatings.
If this is the OM fisheye as I think, I would leave any repairs to a good camera/lens tech - too valuable to stuff up.

Dec 08, 2017 | Olympus Cameras

1 Answer

I purchased a televue ranger at an estate sale, have since be informed that there is fungus on the lens. When looking at the lens there is a geometric patter around the outer rim, on the inside. How would...

I would contact Televue and see if they can clean the scope. I would NOT disassemble the lens cell, there are two or three lenses on that scope that must be centered and adjusted using an optical bench. DO NOT take them apart unless you know how to collimate the optics.

Feb 25, 2010 | Televue Ranger (160 x 70mm) Telescope

1 Answer

Sigma 70-300 4-5.6 DL has some fungus & blur

Fungus etches the glass. This cannot be fixed by just removing the fungus. The lens has to be resurfaced, calibrated, coated and
well, you get the idea. lots of expensive precision equipment and a jig to recalibrate the focusing after you do all that.
Another 70-300 on Ebay is much less expensive.

Dec 18, 2009 | Sigma AF 70-300mm f/4.0-5.6 DL Macro Super...

1 Answer

Clean fungus rear lens

Oh This Could be a problem. But try just wiping it with a lens cleaning kit. If that dosnt work take it to a camera shop and let them work on it.

Aug 28, 2009 | Nikon Telephoto AF Micro Nikkor 105mm...

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