Fungus and dust and mold, oh my!

[Johnathan]

Hey guys, I have some lens questions for ya'll.

First off, I have a 70-200 f/5.6 k-mount manual lens. When I look through my viewfinder with this lens on, it looks like the glass it looks dirty. So, I get out my lens cloth and rub away, but it is still dirty. Upon further inspection, I see little white spots, but they're on a secondary glass, just inside the one that i can clean. Is there any way to take this thing apart so I can clean that lens, or do I have to send it off?

Also, I've been looking at lenses on eBay. On several of them I see that they will say something like 'there is some dust on this lens, but it does not show on the picture'. Does this mean that it is inside the lens, and I won't be able to clean it? Also, should I trust them when they say that it doesn't affect the image quality?

Thanks for your help!

 

[Kodan_Txips]

Fungus is perhaps more problematic than a FEW bits of dust, as it may affect how much light gets through, and the nature of the light. A few dust specks won't show on the photo, it is only when there are loads that it will have an effect.

If you can see through those little white spots, they wont hurt much - that is, if they are more like a "bloom" or oil slick effect on the surface, visible only when they catch the light at a certain angle. If they are milky dots then they are a problem.

BUT, unless you are a highly skilled lens mechanic, I wouldnt recommend taking the lens apart, especially to fiddle with internal elements. The milky fungus dots will slowly degrade the picture, over the years. You could totally ruin the lens in an evening!

Take it to a repairman, but you will probably find the repair costs more than the lens is worth.

Ebay has such bargains, I wouldn't buy a lens where the seller actually admitted to dust, fungus etc. Find a lens that claims to be mint condition, optically perfect, etc. The price premium is worth it just for peace of mind. And if they admit problems, they are probably worse than stated.

 

[Johnathan]

Airgunr posted a link to http://www.keh.com/ in another thread. I did their online quote thing, and it estimated that it would cost about $35 to defungus my lens. I am tempted to send it in, just for the peace of mind that the lens is in good shape optically. It would be better than taking a chance on another on ebay for me.

 

[Kodan_Txips]

It depends on the zoom, really. I don't know the standard price of the one you are talking about. If it is a Pentax branded, I reckon it may be worth the 35 dollars and postage. If it is only a third party lens, maybe a second off ebay would be a better investment, as you could keep your current one as a backup, or have the 2 at slightly different zoom ranges, or even keep the new one and have fun taking it apart and risking ruining it. (And if you made it perfect, you get maximum street cred!)

One important point. Have you used the lens yet? Never mind about its condition, do you like the results? If so, take a few test shots now, and store them carefully. If in a year or 2 you lose confidence in the lens, take the same shots at the same settings and conditions, and compare them. If the image has degraded enough to worry you, THEN get it serviced. Since you have fungus now, if you got it serviced now, you might find that you would still need to get it reserviced more often in the future anyway.

That's the cheapest option too.

Never worry too much about the condition of stuff if the results are good. Top quality work often comes from pros that are working on location, with gear that is in a horrifying state of repair.

 

[Kodan_Txips]

Another point springs to mind. At 35 dollars I doubt if keh are going to dissassemble your lens and lovingly polish every surface, much less reapply the lens coatings that the fungus will have destroyed.

I think it is more likely that they are going to do something like fumigate the lens, and/or give it a good soaking in some sort of fluid bath. (Or am I thinking of stripping pine furniture?)

The fungus, when removed, could still leave variations on the lens elements, where coatings have been removed or altered chemically. They won't affect the photo much, if at all, but you may still notice them.

 

[Rob]

Some lens mould can be killed off and bleached away with UV radiation (or sunlight as it's normally called). If you have a safe way to leave the sun shining through the lens (without setting fire to anything), then I've heard that this can help. ksmattfish is probably the man to help, as he has quite a collection of older items.

If you take a zoom lens of that length apart, you've got two hopes of getting it back together - and Bob's out of town. The measurements involved are literally microscopic, so there's a real skill to doing it.

As has been mentioned, you just aren't going to get a proper service for $35 - they'll probably just drop it into a ultra-sonic oil bath and possibly heat it in an oven to burn off the stuff.

Rob

 

[phillll]

they say on keh.com that its 35$ for them to look at it and see how much to it is to repair it and if you decide to get it fixed there they will waive the fee

 

[Kodan_Txips]

That's a bit tricky. They look at it, quote 100 dollars, you choke and demand the lens back, and they have it as a hostage.

I can understand them doing it, of course, but 35 dollars MORE to find that the repair is uneconomical is a further burden.

I recommend using the lens for a while, see what the results are like. Forget about repairs or a second lens, unless you can find one with a slightly different zoom ratio, or much lighter, so they don't overlap.

Look for a mint condition 75 - 150, maybe?

 

[Johnathan]

I just sent off a roll of film taken with the lens. I guess we'll see Monday what kind of pictures it takes. I may try putting it in a window too.

Thanks for your advice!

 

[Rob]

I may try putting it in a window too.

Don't forget what I said about setting fire to things!! I wouldn't want you to burn your house down on my advice. Prop it in an oven tray or something fire resistant, not on your sofa or near your curtains/carpet or whatever.

 

[Johnathan]

Don't forget what I said about setting fire to things!! I wouldn't want you to burn your house down on my advice. Prop it in an oven tray or something fire resistant, not on your sofa or near your curtains/carpet or whatever.

Hehe, will do...Though that would be an interesting lawsuit, 'Man burns down house due to internet advice. Story at 10.'

***edited for a typo***