Fungus removal?

[shtfmeister]

I am interested in a used 500 f4.5 but the seller said the glass has some fungus.
can this be cleaned/fixed or is it a walk away it's only going to get worse situation?

 

[TexPhoto]

it can be fixed, but a complete tear down - rebuild of a lens like hat can be $1000+.

This is my repair shop: http://www.sp-ts.com/ Call them or similar, describe the problem and try and get an idea what it will cost.

 

[shtfmeister]

thanks if i buy it i'll give you a call

 

[Mt Spokane Photography]

A repair shop needs to see the damage. Fungus can etch the glass and make a lens worthless, or a cleaning might do it. The old 400 500mm f/4.5 does not have new parts available for it, so a repair shop might have to locate used parts.

Be very careful, older lenses that have limited parts availability are often good for parts only. Why doesn't the seller have it fixed? Chances are he already knows something.

 

[dr croubie]

I've had some experience with fungus on old glass before, here's my experience:
Bought a set of 3x Zeiss lenses for Pentacon Six off ebay, I knew it was a gamble but the price was right, all 3 had fungus in some way.
The 180/2.8 Sonnar had fungus internally, around the inside of the front element.
The 50/4 Flektogon had it about in the centre of a middle element.
The 80/2.8 Biometar had both dust and fungus in the centre of the element just in front of the aperture.

Firstly, they all went in the sun for a few days to kill all the spores (Be careful, I nearly set fire to my lawn), aperture as open as possible.

So, the Sonnar 180 only had fungus around the rim. It's got a 6*6cm medium format image circle, and an 82mm filter ring. I can attach step-down rings to 58mm without vignetting on my 7D. The fungus was nowhere near the image circle on APS-C. What camera do you have? If you're on APS-C or even APS-H and the fungus is right near the rim only, you could be lucky if you kill it properly and it doesn't spread.

The Flektogon 50 I took the rear few elements off, with a blower and microfibre cloth I managed to clean all the dust and spores out, this lens works fine now.

The Biometar 80 I also took the rear elements off, but the screw threads were very sticky and it took a lot of straining. Cleaned it off alright, the fungus had etched into the glass and multicoating around the edge but nowhere near the APS-C image-circle. But then I put it back together, and couldn't line up the elements exactly. So now it's got a bit of a "soft-focus" effect wide-open, still sharp as nails at f/5.6 or so. I don't use this very much anymore. I could probably try playing around with the element spacing to get it back to sharp at f/2.8, but I could just as easily buy another off ebay for $50-100, and i'm too lazy to even do that now that i've got an EF 85/1.8.

Otherwise, you'll have to inspect it closely, if it's just fungus it's fine, if it's etched into the coatings you just get a bit more flare, but if it's etched into the glass then you 'could' start to see it affect IQ. You can also take a gamble, if it's only one lens element affected, then maybe you can strip it for parts and make a bit of cash, but not if you want to actually use it.

 

[shtfmeister]

I've got a 7D

You can also take a gamble, if it's only one lens element affected, then maybe you can strip it for parts and make a bit of cash, but not if you want to actually use it.

thats the problem i want to use it.
the more I think about it the more I think I should hold off.

 

[dr croubie]

I've got a 7D

Best thing I can suggest, is if the fungus is only around the edges on the front element, just hold up your hand or a piece of paper around where the fungus is, and if it vignettes, then it's in the region to affect IQ. I'd be happy buying it if it really were only on the edges, and if i could inspect it beforehand, but if it's near the middle, or not-well-described on ebay then I wouldn't bother...

 

[Hillsilly]

If you live in a hot, humid climate and you are likely to take the lens out in the rain occasionally, then those conditions are likely to encourage fungus growth and I'd be less inclined to buy a lens with pre-existing problems. If you live in an arid region, it might be less of a risk.

Just be warned that even if you have the fungus professionally removed, this may not be 100% successful in the long term. It is really difficult to remove all of the the spores and re-occurence is common. I know from personal experience, having lost my favourite 400mm lens to it.....

Supposedly, there is also a risk that your other lenses could become infected. But that just might be an old wives tale? Fungal spores are everywhere so owning an infected lens probably doesn't increase the risk to other lenses dramatically.

So, as other people have mentioned, don't discount the idea completely. There are different types of fungii that affect lenses. Some are easy to fix and aren't necessarily fatal. But have a look at the lens first and weigh up the risk that the lens could become useless very quickly. Personally, it would have to be a great sale price for me to take that chance.