[Vormulac]

Hi folks,

I know fungus is a 'bad thing' in terms of lenses, but I was thinking of buying a mirror lens second hand which has been described as possibly having a tiny patch of web fungus. Should I just steer clear? Is it something I can live with (don't mirror lenses have filters screwed on the rear, so nothing nasty could come out into my camera anyway?), is it something I can get rid of?

I'd really like this lens. What are your thoughts?

Cheers!

[Wheatfield]

For myself, any lens with fungus is one to be avoided.
Consider that if fungus was able to get into the lens, it will be able to get back out too, possibly affecting every lens you own.

[Vormulac]

That's a good point. I'm guessing having lenses cleansed of the evil mould-pox is an expensive undertaking?

[wallyb]

Light fungus will do almost nothing, if anything at all, to the image quality your lenses produce.

However, light fungus can and will spread to your other, currently clean and safe lenses.

Light fungus, if not properly taken care of, can always develop into heavy fungus which can literally ruin a lens, physically damaging the glass and severely degrading the IQ.

If you catch fungus when it's light and fully clean it out, it will have just as little chance of spreading/coming back as any other clean lens -- usually little if taken care of well.

But using a lens with any amount of visible fungus in it is not recommendable, unless it is cleaned professionally first.

[Vormulac]

How much have people paid to have infected lenses cleaned? I would like this lens, but sounds like I would have to factor a professional clean into the price.

[wallyb]

How much have people paid to have infected lenses cleaned? I would like this lens, but sounds like I would have to factor a professional clean into the price.

My local place does a full internal cleaning, including fungus, for $40-70 per lens.

[atiratha]

Has anyone ever heard of fungus transfer? I haven't. As we all exist outside, our lenses must be full of funghi spores that just wait for the lens to be deposited somewhere dark and wet. As long as you keep it in a relatively dry place (the usual shelf is ok), the fungus should neither grow, nor transfer.

[GerryL]

Has anyone ever heard of fungus transfer? I haven't. As we all exist outside, our lenses must be full of funghi spores that just wait for the lens to be deposited somewhere dark and wet. As long as you keep it in a relatively dry place (the usual shelf is ok), the fungus should neither grow, nor transfer.

This is not just the case 'coz if you mount a fungus infected lens on your camera body, then the fungi spores can get into the body too and infect all the other lenses that you would mount.
The spores can lay dormant and wait for the right conditions to grow.
With a right environment, all your equipment will be growing mushrooms!

[Phaser]

take a look here https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/40521-dead-lens-club.html

[Blue]

While it is a good idea to buy a fungus contaminated lens unless it is minimum and it is a lens worth having cleaned by an expert, fungi are ubiquitous in the environment. In other words, if you don't store lens in a dry place (low relative humidity) any lens you own can establish a fungus culture. There are 1000s of species of these damn things all over the place.

[Just1MoreDave]

I know fungus is a 'bad thing' in terms of lenses, but I was thinking of buying a mirror lens second hand which has been described as possibly having a tiny patch of web fungus. Should I just steer clear? Is it something I can live with (don't mirror lenses have filters screwed on the rear, so nothing nasty could come out into my camera anyway?), is it something I can get rid of?

I'd really like this lens. What are your thoughts?

I would be cautious of fungus on mirror lenses, because the mirror is like the SLR mirror, all on the surface. It's trickier to clean and may be more easily damaged by the fungus. I'm also cautious because I've never taken apart a mirror lens. I suppose both worries are less of a concern for a professional.

Fungus eventually will etch coatings away. You can't be sure what the damage is until it's gone, so every infected lens is a bit of a gamble.

[rhodopsin]

Has anyone ever heard of fungus transfer? I haven't. As we all exist outside, our lenses must be full of funghi spores that just wait for the lens to be deposited somewhere dark and wet. As long as you keep it in a relatively dry place (the usual shelf is ok), the fungus should neither grow, nor transfer.

+1

Fungus is EVERYWHERE, including those brand new lenses, even if the lens is hermetically sealed and internal air is replaced with nitrogen; of course fungus will not grow in nitrogen, but camera lenses are typically not hermetically sealed.

For everyone who says there will be "cross-contamination", please provide evidence of ONE EXAMPLE (there aren't ANY). Certainly fungus growth will appear in any lens stored in a welcoming environment; the spores are EVERYWHERE.

[MattGunn]

+1

Fungus is EVERYWHERE, including those brand new lenses, even if the lens is hermetically sealed and internal air is replaced with nitrogen; of course fungus will not grow in nitrogen, but camera lenses are typically not hermetically sealed.

For everyone who says there will be "cross-contamination", please provide evidence of ONE EXAMPLE (there aren't ANY). Certainly fungus growth will appear in any lens stored in a welcoming environment; the spores are EVERYWHERE.

I completely agree. I don't doubt that fungal spores transfer via your camera but they will will also transfer between lense just sitting next to each other (they are so small that they are airborn and could drify miles on a breeze). If you are not prepared to put a lens that either has or has had fungus on your camera then you shouldn't ever bother buying a second hand lens. In my experience anywhere that has a selection of second hand lenses (especially takumar vintage) will have at least one with fungus and so there will almost certainly be spores on the rest. About a year ago I went on a course about preventing biological contamination of instruments to be sent to Mars as part of the European Space Agency ExoMars mission. Even with a top grade clean room it is IMPOSSIBLE to remove all spores from any piece of equipment even if it brand new!
The best way of dealing with fungal spores is don't give them the conditions they need to grow.

I would be cautious of fungus on mirror lenses, because the mirror is like the SLR mirror, all on the surface. It's trickier to clean and may be more easily damaged by the fungus. I'm also cautious because I've never taken apart a mirror lens. I suppose both worries are less of a concern for a professional.

Fungus eventually will etch coatings away. You can't be sure what the damage is until it's gone, so every infected lens is a bit of a gamble.

I brought a Tamron 55BB mirror lens cheep becaue it had serious fungal contamination. It was not difficult to clean, if anything it was easier than most of the refracting lenses I have dealt with. Unlike the SLR mirror, caradioptric lenses have back surface mirrors where the reflective aluminium coating is on the back of the glass substrate which also doubles as a refracting element. Most reflecting telescopes mirrors on the other hand are front surface mirrors and so as Just1MoreDave said there is a high chance of damage to the coating which would have to be removed and re-coated. Because of the back surface mirrors you don't have to worry about the reflective coating on mirror lenses. However as Just1MoreDave points out the fungus can damage the coating but this takes a long time and I have only had one or two out of about 20 lenses where there is any detectable damage to the coating after the fungus has been removed. If the mirror lens is a good one (Tamron, Sigma, Pentax etc) and it is cheep then it may be a good way of getting a decent lens quite cheep, the chance of serious damage is small.
Bellow is a photo of the inside surface of the front element of my Tamron 55BB. This is now spotless and I have had no problems since cleaning it.

[Ben_Edict]

Hi folks,

I know fungus is a 'bad thing' in terms of lenses, but I was thinking of buying a mirror lens second hand which has been described as possibly having a tiny patch of web fungus. Should I just steer clear? Is it something I can live with (don't mirror lenses have filters screwed on the rear, so nothing nasty could come out into my camera anyway?), is it something I can get rid of?

I'd really like this lens. What are your thoughts?

Cheers!

As MattGunn wrote, cleaning a catadioptric lens is easy, in fact easier, than cleaning a standard lens.

BUT I would only buy a fungus infected lens, if that lens is very desirable and would be prohibitively expensive in a better condition. I did so with the Pentax 28mm Shift lens, which I got as a good deal, because it was infected severely. I cleaned that completely and the lens is like new.

The success rate is nearly 100%, especially if the contamination is only light. But again, It is not worth the effort for a cheap lens. As mirror lenses are almost all quite cheap (with noteable exceptions like the Pentax zoom mirror or the Zeiss Mirotars), the deal should tend towards nill to make sense.

Anyway, a good quality cat lens can be a joy to use, much smaller and more lightweight, than an ordinary lens, though a tripod is also desirable...

Ben

[wallyb]

+1

Fungus is EVERYWHERE, including those brand new lenses, even if the lens is hermetically sealed and internal air is replaced with nitrogen; of course fungus will not grow in nitrogen, but camera lenses are typically not hermetically sealed.

For everyone who says there will be "cross-contamination", please provide evidence of ONE EXAMPLE (there aren't ANY). Certainly fungus growth will appear in any lens stored in a welcoming environment; the spores are EVERYWHERE.

It is not a matter of lenses only getting infected if they're near already infected lenses, it's a matter of there being more ambient fungal spores when you have an infected lens around. It's the speed of development, not the possibility of it. Very simple...