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lens fungus

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beccles View Drop Down
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Topic: lens fungus
    Posted: 27 April 2019 at 11:46
there's a Sony 70-400mm f/4-5.6 G SSM on ebay atm, but the seller says it has early signs of fungus. From the pics it doesn't look too good, though he still wants near £500 for it. eBay item number:382904365520 if you want to have a look.

What are the effects & likely progression of lens fungus, and can it be removed? (i'd imagine this would be a costly exercise if it's possible)
 



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mike77 View Drop Down
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Post Options Post Options   Quote mike77 Quote  Post ReplyReply Direct Link To This Post Posted: 27 April 2019 at 12:30
At this stage, it probably won't have any noticable effect on image quality. If stored in a dry place, I expect the fungus to grow only slowly or not at all. It also seems the front element is affected, which is easy to access and clean. So overall, it may be worth the risk if one wants to get this lens for a low price.
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darosa View Drop Down
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Post Options Post Options   Quote darosa Quote  Post ReplyReply Direct Link To This Post Posted: 27 April 2019 at 13:31
I wouldn't buy this lens with fungus for £500. You don't want that in your lens; it can be cleaned but as you say it will be costly especially if you send it to Sony repair. As prices of A-mount lenses are very 'buyer-friendly' I would look elsewhere.
I have one for sale. No fungus, glass and lens in excellent condition. PM me if you're interested!
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 27 April 2019 at 13:56
Pay the extra and get darosa's ! ( Or from someone else's that hasn't come from a mushroom farm like the one you ask of ) .
If you don't deal with it it can not only spread within the lens , but to other lenses as well .
The spoors are in the grease not just on glass surfaces , so to clean it properly it would be an expensive job .
More than the cost of just buying one in good condition already .
Untill you have a proper look at it , you can't tell how bad the infestation is .

Walk away from it
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Post Options Post Options   Quote waldo_posth Quote  Post ReplyReply Direct Link To This Post Posted: 28 April 2019 at 18:16
This is a clear advice against buying any lens with fungus.
It is not the fungus as such that is harming but the products of its metabolism (acids) that leave irreversible marks on the glass.

Zeiss does not accept any lenses infested with fungus for repair - see the last sentence on this page.
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2019 at 11:56
how does this fungus get into the lens?
 



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Post Options Post Options   Quote owenn01 Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2019 at 12:01
Originally posted by beccles beccles wrote:

how does this fungus get into the lens?


It can get in through the rear element area when you take the lens off the camera for example; even though we are usually quick to re-cap the rear housing even then it's long enough for a small number of spores to get in then 'track' through the assembly until they find a nice, warm place with plenty of food (ie the adhesives and grease used internally) to start growing.

if the lens is or has been used or stored in nice, warm, humid places then that also helps the growth along nicely!

I would also err on the side of caution with such a special lens as this - it won't be cheap to have fumigated!

Best regards, Neil.
My Mantra: "Comment on other's work as you would wish to have yours commented upon". Go on - it's fun!
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beccles View Drop Down
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2019 at 12:08
ok, thanks. TBH i'm still not sure whether it's worth going the 400mm (especially at that price!) as most of my shooting is walkabout birding & handheld, and i'm not sure at 400 i'm going to get any better results than my current tamron 70-300.. i would post some pics for your judgement but though i've asked a few times how to do it, no-one has told me how to post pics on here, so i'm guessing you can't & need to use something like flickr??
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Post Options Post Options   Quote owenn01 Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2019 at 12:14
Originally posted by beccles beccles wrote:

i would post some pics for your judgement but though i've asked a few times how to do it, no-one has told me how to post pics on here, so i'm guessing you can't & need to use something like flickr??


Hi - Yes; unfortunately you do require an on-line hosting site such as Flickr to be able to post on to Dyxum. There are lots of other sites out there (Flickr is free unless you are hosting large numbers of images; others are available which are free though) and it really is a simple process once you are up and running.

Best regards, Neil.
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2019 at 14:05
Originally posted by beccles beccles wrote:

how does this fungus get into the lens?


You don't even have to take a lens off the camera .
The fungi spoors are in the air , when you zoom out the lens gets longer and sucks air in , once the spoors are in they just need the right conditions to grow .
Even weather sealed lens aren't impervious to it .
Zoom out and you pump air into somehow , even if the air gets in via the camera body , the air is still getting in from the outside world .
Prevention of letting it start growing is easier than trying to eradicate it afterwards .
see my photostream on flickr;
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Post Options Post Options   Quote vitor Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2019 at 07:57
If the fungus didn't cut into the lens coating, it can be "easy" to clean. Getting to the lens element can be tricky depending on where it is.

If you can finantially, as others have said, avoid buying a lens already contaminated.
If it is one of your lenses, there are several tutorials available in the net on how to remove fungus. Eventually it will show again, if the conditions are right.

It's not as uncommon as we are made to believe, and certainly not the end of the world either. Using the lenses is the best way of preventing it to show.
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2019 at 14:49
It is said that every lens which is not 100% sealed will have fungal spores in it, but they need the right conditions to grow, and it is the growth across optical surfaces that causes loss of contrast.
It is also said that by the time fungus shows on the glass, a lot more of it will be everywhere else.
It is possible to clean lens glass surfaces (I've done it too), but I would still be reluctant to store it in the same place as my better lenses.

Re lens choice, the 70-400 is much bigger, heavier, and difficult to hand-hold than the typical 70-300mm zoom, but it is much sharper and more contrasty than the 70-300s. Read Kurt Munger's comparison.
Miranda F & Sensorex, Sony A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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beccles View Drop Down
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Post Options Post Options   Quote beccles Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2019 at 14:58
thanks for that.. but i'm guessing that though the 70-400 is apparently sharper than the 70-300, as evidenced by the pics on the comparison, at 400mm hand held it quite possibly wouldn't be?
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stiuskr View Drop Down
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Post Options Post Options   Quote stiuskr Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2019 at 15:43
I've never had a problem hand holding it at 400mm if you can keep the shutter speeds up where they need to be, I've tried it with a monopod and tripod and find that just slows me down if panning and tracking shots are involved.
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