I have an old (circa 1995 I reckon) Sigma 28-200 zoom lens from the days of 35mm film and I want to use it on a digital body. It fits a DSLR okay but the trouble is, it’s a bit misty and I just wondered whether there’s any mileage in trying to clean it instead of just chucking it away? There are some screws on the mount but I’m guessing they’re not really designed for home maintenance.

(I’ve obviously had a go at cleaning the outer glass but this looks to be inside somehow)

Not unless you know what your doing, try it, and you will find there are far too many tiny parts to ever get back together again and in the right order.

Would imagine that it would be a lot cheaper to replace with a new one, rather than get this one stripped & serviced.

would be a lot cheaper to replace with a new one

Cheers, I realise a professional job would be daft but don’t want to just throw it away so might as well have a go. I’ve repaired a couple of mantle clocks in my time so you never know!

I’ve stripped and cleaned a couple of lenses. Have a google, you may well find a how-to guide.

You can usually get a couple of the element groups out really easily, which may be enough. As you plan on binning it otherwise it’s not like you have anything to lose.

Its possible on some lenses to take the front element off for cleaning, remove the rubber seal then three screws.
Blow out the dust with a rocket blower then make sure the glass goes back in exactly the same place

Wouldn’t suggest going any further than that though

it’s not like you have anything to lose

Quite right, I’ll have a google about and start the dissection this evening..

Blow out the dust with a rocket blower

It looks sort of greasy somehow, could even be mould I guess if it got damp somehow. Thanks for the tip.

The correct answer is yes.

The correct question, however, is do they go back together again and the answer to that I’m afraid is no.

Quite right, I’ll have a google about and start the dissection this evening..

Don’t forget to post pics of the operation … 🙂

Don’t forget to post pics of the operation

Could be quite amusing! A pile of parts on the kitchen table before I sweep them into the bin?

Sounds like fungus which is a non-runner, best bin it and stop the spread to any other lenses

Sounds like fungus which is a non-runner, best bin it and stop the spread to any other lenses

Boooo. That’s bad news. I only have this one lens at the moment but that is a worry.

they do come apart, finding how they come apart can be tricky. My tip would be to take photos at each step so you can see what bit goes where. Might be tricky without a lens I spose 🙂

I took my 18-200mm sigma IS lens to bits when the zoom barrel broke, was pretty straightforwards, despite all the electrics compared to an older lens

Also many older Sigma lenses need rechipping to work with modern DSLR’s, I know at least they do with Canon otherwise they give an error message.

was pretty straightforward

There’s some hope then, like the idea of taking photo’s as I go, that should help. I have a reasonable close-up camera on the phone so should be possible. When I’ve done clocks I’ve spent ages drawing diagrams of how they fit together, ever seen a Westminster mantle clock in pieces? Jigsaw from hell!

Also many older Sigma lenses need rechipping

We tried this one today in a DSLR and it didn’t complain so I’m optimistic about that. The owner of the DSLR body said the AF was behaving a bit strange but it still worked.

Might be worth taking a photo of the “greasy” element and posting it up first. Get a bright light on it/behind it. If it’s a bad case of fungus it won’t be worth trying.

If it’s a bad case of fungus it won’t be worth trying.

As in it will never be sharp again? When you look through the viewfinder it just looks slightly hazy, like there’s just dust on the lens. Taking it off and examining it shows up best on full zoom, looking down the non-mount end. It has no colour, if you can imagine a piece of glass that’s been constantly scratched so it goes rough, it looks a little like that..

If it’s a bad case it’ll be between the sealed elements so you won’t be able to get at it. If it’s just the odd splodge you can usually get at it and remove it (which it doesn’t sound like). The fungus eats the lens coatings so even if you can get it off it can leave a pitted surface.

If you can get a close-up picture (or get a good look at it), if it’s fungus you should be able to see some organic patterns (like river networks) where it’s grown.

It could be oil, or dust though.

if it’s fungus you should be able to see some organic patterns (like river networks) where it’s grown

I wondered about that, there’s definitely no regularity, nothing like a petri-dish culture. Let’s hope for dust/oil. No chance of getting a photo I’m afraid, that would require a decent camera with a decent lens, I think that’s where I came in!

Let’s hope for dust/oil

Edit – I googled lens fungus and amongst the pictures of mushrooms atop camera lenses I saw a few disturbingly familiar images. Not exactly the same but close enough.

I did this with a cheap ebay lens. I stripped it down as much as I could be bothered to and cleaned the lenses with antiseptic wipes. There were a couple of elements inside a bit that I didn’t fancy getting into so I left them. After assembly it was better but not good enough. I would recommend that if your going to do it then do it properly and get it stripped fully. It was easy enough as it went.

I’ve done it with a simple AF zoom, worked a treat. Then I got cocky and tried it on my M42 Helios manual focus lens. After 5 attempts to get it back together correctly I still cant get infinity focus.

It was easy enough as it went

[quote]worked a treat[/quote]

Keep ’em coming!

get hold of another lens the same and practice on that one to make sure you know what you’re doing.
better to get one in perfect nick, then you can compare the parts you think have fungus/ oil side by side.

This site may give you some insight into what you’re up against………….

Good luck!

This site may give you some insight into what you’re up against

Awesome – springs, tension, tiny parts – a recipe for disaster. And this one didn’t even have any AF electronics!

better to get one in perfect nick, then you can compare the parts

Haha – If I had one of those I wouldn’t be here!

Stick it in a pillow case and put in with your whites…it’ll come out gleaming (possibly).

But in all honesty I shouldn’t think it’s worth the bother to get it professionally done. Unless it’s really fancy, you could get a brand new one for £200-300.

Although if you decide to just buy a new one you may as well have a go at cleaning it yourself.

you could get a brand new one for £200-300

I wouldn’t live to tell the tale.. Non-bio would be best I assume, what about fabric conditioner?

I’ve some pentax lenses (50mm and 28mm) that have fungus, the images are still pretty good though so CBA with replacing them.

Update – See inside for pics of a fully disassembled Sigma 28-200! (just before it went in the dustbin).

Alas, the fungus was buried deep inside the lens, there was no hope and I’m afraid the patient didn’t come through. In the pic below it was inside the back of the ‘turret’ (middle row, 2nd column) and the only way in there was with a pair of wire cutters to separate the electrics and give me access. Interesting to see how it all worked though..

So, now the seed has been planted I need to find a cheap starter DSLR, £180 for a D70 with an 18-55 and a 6 month warranty or an EOS 300/350 off ebay?