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03-15-2014, 03:57 AM   #1
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Hazy rear element

What is this? It's on the rear element and looks to be inside because I tried my lens pen on it and it's not coming off. This is my Sigma 70-300mm APO non DG Macro lens. And can it be fixed?



03-15-2014, 05:11 AM   #2
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lens haze

Thats looks like fungus to me! I have had lenses with haze, haze tends to look whitish, and be smooth,or patchy this looks spotty - fungus can often look like this.

I have had good experience generally cleaning off fungus, even off very old lenses. However there is always a bit of uncertainty as to how fungus might affect coating or the underlying glass (plastic?). The first problem is accessing the lens element. I don't seee any slots for a lens spanner on the rear element. It may be part of an integral unit. Sometimes these are not really designed to be disassembled, at least not by amateurs. perhaps s/o else has more direct experiene with this lens.
03-15-2014, 05:26 AM   #3
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Thanks Marcus. I am going to try the tip I read earlier about laying the lens in direct sunlight for a few hours and see if that helps. I believe the lens on this is actually glass not plastic. if that doesn't work, it may be time for a new lens. I am not comfortable taking lens apart, especially this lens. I have taken other lenses apart but not to clean an element. And as shaky as my hands are now days, that would probably end up as a disastrous clean.
03-15-2014, 07:21 AM   #4
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Try asking a friendly "techie" at a camera shop. Sunlight isn't going to take off this I'm afraid.

03-15-2014, 07:54 AM   #5
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No close camera shops around here and I don't drive long distances to bigger cities. I'm just going to buy another zoom. Maybe get the Pentax 55-300mm this time around.
03-15-2014, 09:20 AM   #6
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I agree that you should start looking for a replacement lens. But later on, if the lens still bothers you:

I would try unscrewing the three black screws just inside the chrome mount, probably holding in a plastic light shield that covers the gap between the mount and rear elements. Then I'd see if the whole rear group comes out as a subassembly, one aluminum tube with a threaded end. That subassembly might come apart enough to access all of the internal elements. I haven't seen this lens, but my general inexpensive Sigma experience is not encouraging. The subassembly might not come apart at all. The haze doesn't really look like it wipes off either.
03-15-2014, 01:03 PM   #7
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Thanks Dave. I'm pretty handy most times about taking electronic things apart or dealing with disassembling them. I repair laptops, sometimes having to tear them down completely, to repair them. So a lens shouldn't be that difficult, yeah, right!

I've been looking at getting another Sigma lens. KEH has several I'm tempted with. This was a good lens and I didn't pay that much for it, but it's the lens I took my avatar photo with, among other birds/egrets, etc.
03-15-2014, 06:39 PM   #8
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I have this stored on flickr and BlackCloudBrew commented and said he's never seen fungus like this, he's also said he's no expert but thought fungus was a growth from out to in and had spikes. You can read what he said if you click on my photo above it will take you to my photo on flickr. This doesn't have spikes and it is starting to look more like a coating of some sort on the outside not inside.

03-15-2014, 06:49 PM   #9
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Delamination?
03-15-2014, 07:45 PM   #10
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Not sure about that either Arnold, thanks for suggesting it. I looked this up on the web and found an article that describes this but it said there would be a rainbow effect, and this lens doesn't have that.

Here is the article:
Markus Keinath - Delamination and Seperation of Lenses

EDIT: I have another lens on it's way as soon as KEH ships it. Said estimated delivery would be Friday the 21st.
03-15-2014, 09:36 PM   #11
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Could it be mineral deposited from condensation? I have cleaned such from the rear glass of a few old Mamiya TLR lenses which looked to my eye like hard-water stains. A moistened finger dipped in citric acid powder (in the canning aisle with the mason jars) gently cleanses the mineral deposit away. That is, if it is calcium deposited by moisture. This is how we used to clean old bottles we dug up in the desert, if we didn't shoot them first.
03-15-2014, 10:39 PM   #12
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QuoteOriginally posted by AquaDome Quote
Could it be mineral deposited from condensation? I have cleaned such from the rear glass of a few old Mamiya TLR lenses which looked to my eye like hard-water stains. A moistened finger dipped in citric acid powder (in the canning aisle with the mason jars) gently cleanses the mineral deposit away. That is, if it is calcium deposited by moisture. This is how we used to clean old bottles we dug up in the desert, if we didn't shoot them first.
Thanks for the tip, I'll try that soon as I can get to the grocery store.
03-16-2014, 07:34 AM   #13
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There are some great pics of lens fungus here:
Markus Keinaths Photohomepage - Lens Fungus
However I stand by my earlier post - fungus can certainly look like the OP's example. I don't think its delamination - that typically has optical eg rainbow effects. Some condesation is very possible - a contributory factor, fungus requires a certain amount of humidity.

QuoteOriginally posted by Just1MoreDave Quote
I would try unscrewing the three black screws just inside the chrome mount, probably holding in a plastic light shield that covers the gap between the mount and rear elements. Then I'd see if the whole rear group comes out as a subassembly, one aluminum tube with a threaded end. That subassembly might come apart enough to access all of the internal elements. I haven't seen this lens, but my general inexpensive Sigma experience is not encouraging. The subassembly might not come apart at all. The haze doesn't really look like it wipes off either.
+1 except I would be more confident that if you can access the relevent elements it will clean off (I use tissue dampened with a smidgen of household mould and mildew remover wrapped around an old sensor cleaning spatula with a twister). Give it a go!
03-16-2014, 08:25 AM   #14
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Removal of that lens for cleaning doesn't require a spanner and can be done by removing the mount screws and lifting the mount off.. then the rear of the lens is a cap type and unscrews counter clockwise. It is a fairly easy to do. Just be careful to pay attention to the positioning of the mount when removing or it can take some time and effort to figure how to put it back right.. You can use a rubber band or something of that nature to grip the sides of the lens casing for easier removal. If it won't unloosen with that then you can carefully use a pair of pliers with a rubberband or something to protect the sides to free it. If it is clouding then it can be removed with lens cleaner. If it is fungus it can be removed with isopropyl alcohol. If that wont clean the fungus you can use cold creme letting it harden then clean with it with the alcohol. if there is fungus or clouding on the lenses underneath that one then that requires a lot more skill.

PS if you attempt this try to work in as dust free environment as possible and wear powderless non latex gloves.

Last edited by Oldbayrunner; 03-16-2014 at 08:37 AM.
03-16-2014, 09:58 AM   #15
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QuoteOriginally posted by marcusBMG Quote
There are some great pics of lens fungus here: Markus Keinaths Photohomepage - Lens Fungus
However I stand by my earlier post - fungus can certainly look like the OP's example. I don't think its delamination - that typically has optical eg rainbow effects. Some condesation is very possible - a contributory factor, fungus requires a certain amount of humidity.
None of the photos he shows on that page resemble what's on that lens of mine. These show spidery web there and mine is just as you see in the photo but with one exception, the whatever that is looks cloudy and white. I don't know if it would show the spider web look to it under higher magnifaction or not.

QuoteOriginally posted by Oldbayrunner Quote
Removal of that lens for cleaning doesn't require a spanner and can be done by removing the mount screws and lifting the mount off.. then the rear of the lens is a cap type and unscrews counter clockwise. It is a fairly easy to do. Just be careful to pay attention to the positioning of the mount when removing or it can take some time and effort to figure how to put it back right.. You can use a rubber band or something of that nature to grip the sides of the lens casing for easier removal. If it won't unloosen with that then you can carefully use a pair of pliers with a rubberband or something to protect the sides to free it. If it is clouding then it can be removed with lens cleaner. If it is fungus it can be removed with isopropyl alcohol. If that wont clean the fungus you can use cold creme letting it harden then clean with it with the alcohol. if there is fungus or clouding on the lenses underneath that one then that requires a lot more skill.
PS if you attempt this try to work in as dust free environment as possible and wear powderless non latex gloves.
Thanks for the instructions oldbayrunner, I'll give it a go once I get the other lens here in hand.
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