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ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

Started Aug 4, 2014 | Questions
mjkshots
mjkshots Regular Member • Posts: 140
ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

does anyone have a good instructional video/photo/written explanation on how to open up and clean the inside of a 300mm f2.8L USM NON-IS LENS ? there is some stuff on one of the internal elements of this lens. check out the pics.. I think it is on the focusing element or possibly the element in front of that one. thanks for the help

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-mike
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hotdog321
hotdog321 Forum Pro • Posts: 21,141
Re: ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

mjkshots wrote:

does anyone have a good instructional video/photo/written explanation on how to open up and clean the inside of a 300mm f2.8L USM NON-IS LENS ? there is some stuff on one of the internal elements of this lens. check out the pics.. I think it is on the focusing element or possibly the element in front of that one. thanks for the help

Yikes! I own this same lens. Hope it's just dust and not fungus. I'd be interested in an answer, too, since I don't think Canon will service this pricey bad boy anymore.

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Canon EOS 5D Mark IV Canon EF 100mm f/2.8 Macro USM Canon EF 70-200mm F2.8L IS II USM Canon EF 24-70mm F2.8L II USM Canon EF 16-35mm F4L IS USM +3 more
bronxbombers4 Veteran Member • Posts: 3,387
Re: ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

yikes! hope that is not mold! or some sort of coating failure.

it seems very strange to get dirt like that....

Roger at Len's Rentals might know

it can be tricky to take apart, alignment has to be perfect when you put it all back

even though canon no longer has parts, they can probably do cleanings still, but if it is fungus they won't and if it is an element gone bad they don't have more (maybe you could find a broken one cheap on ebay and get the part from that and then have them replace it, if need be)

Ken Christie Senior Member • Posts: 1,278
Re: ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

Assuming, as others say, that Canon Service in the USA no longer support this lens, I would have thought that independent and highly regarded optical/photographic service facilities must exist within reasonable distance, probably at reasonable cost. A phone call or visit to one might give a better option than getting the toolkit out.

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KenC

mjkshots
OP mjkshots Regular Member • Posts: 140
Re: ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

so upsetting, if its mold/fungus what do you think about setting it up next to a dehumidifier ??

thanks everyone

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-mike
mjkshots.com

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Canon EOS-1D Mark II Canon EOS 7D Mark II Canon Pixma Pro-100
bronxbombers4 Veteran Member • Posts: 3,387
Re: ef 300mm f2.8 L non-IS internal gunk! cleaning internal elements

mjkshots wrote:

so upsetting, if its mold/fungus what do you think about setting it up next to a dehumidifier ??

thanks everyone

too late if that is it, you need to do that before it invades

(but don't give up hope yet, it might be something else)

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