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Help! Mold in Sigma 50-500 OS

Started Dec 16, 2019 | Questions
K C L New Member • Posts: 3
Help! Mold in Sigma 50-500 OS

Hello,

Has anyone had any success removing the second element from the front of the Sigma 50-500 OS? I am trying to clean some mold that I *hope* is just on the front of the third element. Removal of the first big element was very straight forward (just unscrewing the 6 screws from the bayonet mount), but I can't seem to figure out how the retainer ring holding the second element/group in place works... It looks like there might be a series of shims placed above the element, unless that is the retaining ring -- in which case it looks like it might have 3 slots, but they look very shallow so I do not want to poke anything in there without confirming that that is indeed the retaining ring...

Alternatively, could it be that it is held in place with a slot-less retaining ring that I may be able to remove using a friction tool of some sort? Or will I have to disassemble the barrel to have a chance at getting behind the 2nd element/group?

Cheers!

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Sailor Blue
Sailor Blue Forum Pro • Posts: 15,536
Re: Help! Mold in Sigma 50-500 OS

A little mold won't degrade the lens much. It may be best to simply leave for now.

You can largely stop the mold from growing by keeping your lenses, an cameras, etc. in a humidity controlled cabinet.

I use one since I live in very humid Thailand and even though I got a fairly large one I quickly filled it to overflow. Be sure to get one larger than you think you will need, you will need the larger size.

eBay - Touch Screen Digital Dehumidify Dry Cabinet Box for Lens Camera Equipment Storage

Lenses have different thickness rings and shims to adjust the position of each lens element to correct for variations in focal length caused by variations in manufacturing.

If you don't have the proper training you are likely to make your lens inoperable by trying to open it up. Removing the mold using the wrong technique and solutions can simply make things worse.

Having a lens serviced to remove mold can be expensive. Buying a replacement lens can be less expensive.

Buy the dry cabinet now and then save up money for a replacement lens.

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Living and loving it in Pattaya, Thailand. Canon 5DS R & 7D - See the gear list for the rest.

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OP K C L New Member • Posts: 3
Re: Help! Mold in Sigma 50-500 OS

I would just leave it alone, except it has already gotten bad enough to definitely be affecting images, especially when shooting towards light source of any kind (unfortunately unavoidable in my line of work sometimes...). I'm dong research in a rain forest, so I've been rolling the dice with humidity and mold for far too long now.

No way to get it sent out to repairs quickly, nor would it be worth the cost since I had purchased the lens used for quite the discount.

Perhaps I should just bite the bullet and upgrade to the Sigma 60-600 Sports....

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