Identifying fungus

[Jack Dahlgren]

Just picked up an old 400mm f/5.6 P.C Auto from eBay and find that there is something on the rear element(s).


I'm a bit worried it might be fungus, but I've never had fungus on my lenses so it is difficult for me to tell what it is.

Any tips for remedying it?

The small number of photos I've taken this evening seem sharp, but it is too dark to really tell.

[richardHaw]

https://richardhaw.com/2016/03/27/repair-fungus-cleaning/

this is how I deal with fungus  some people will have different ways.

that just looks like dirt but can be hard to determine from the picture.

by the way, as for the 400/5.6 family of lenses, i notice that most, if not all examples I see in junk shops have bad rear element groups. this includes mine.

[Matthew Currie]

Interesting.  Most of my old lenses are fine, but my 400/5.6 AI started showing fungus.  Though I rarely use it these days, it seemed too nice to let go, so I took it to my local shop (amazingly, out here in the boonies there is such a thing still) and had it cleaned.  I was told, by the way, that it was a fairly difficult one to do.  Anyway, I wonder if there's something about these that makes them more susceptible, or is it just luck?

[Jack Dahlgren]

https://richardhaw.com/2016/03/27/repair-fungus-cleaning/

this is how I deal with fungus  some people will have different ways.

that just looks like dirt but can be hard to determine from the picture.

by the way, as for the 400/5.6 family of lenses, i notice that most, if not all examples I see in junk shops have bad rear element groups. this includes mine.

When you say "bad" do you mean permanently bad (separation or other permanent damage) or is it something I can fix with cleaning?

[richardHaw]

When you say "bad" do you mean permanently bad (separation or other permanent damage) or is it something I can fix with cleaning?

separation or coating damage as far as i'm concerned (due to condensation of oil and moisture)

i know this sounds weird but trust me, i saw more than a handful that exhibits this. if I find something that happens on 3 or more lenses then that to me is a pattern and is more than coincidental. 

[richardHaw]

Interesting.  Most of my old lenses are fine, but my 400/5.6 AI started showing fungus.  Though I rarely use it these days, it seemed too nice to let go, so I took it to my local shop (amazingly, out here in the boonies there is such a thing still) and had it cleaned.  I was told, by the way, that it was a fairly difficult one to do.  Anyway, I wonder if there's something about these that makes them more susceptible, or is it just luck?

on which elements? 

[pluton]

Jack, I've seen fungus on lenses.  It has always been on internal surfaces.  From your photo, I'm not be to discern the telltale filamentous strands that are typical of the fungus that grows inside lenses. 
See the photos on this website for clear photos:
https://photography.tutsplus.com/articles/all-about-the-dreaded-fungus-lomography-tipster--photo-7737

[Roland Vink]

Just picked up an old 400mm f/5.6 P.C Auto from eBay and find that there is something on the rear element(s).

Looks like dust to me, not fungus. It would be good clean it off regardless.

[Jack Dahlgren]

Thanks all for setting my mind at ease. For some reason fungus seems worse to me than dust, scratches or chips. Maybe because it can keep growing or spread.

The rear element is pretty deep inside so it is going to be hard to get my elbow in there to wipe it off.

I have to say that it is a pretty sharp lens when I manage to hold it steady.

[Bjørn Rørslett]

Use the lens on a regular basis and store it in a dry place. That'll keep it free from fungus.

Most lenses, at the very least those used in the field, will show a lot of dust and grime when you shine a strong light through them.  Usually no harm is done, with the possible exception of fingerprints on the rear element of a very short focal length lens. Don't overclean your lenses as the coating over time might be scratched.

[pluton]

For the rare times a deeply recessed rear element needs cleaning, I made this from a piece of welding rod, two zip ties, and a small alligator clip:

[Jack Dahlgren]

Looks dangerous! Maybe I'll adapt the idea with something wood and softer plastic so I don't get scratches if all goes bad.

[richardHaw]

what we use here in Asia is piece of stick that has one end cut into a wedge, wrap that in lens tissue and secure it with rubber band. the tissue can then be moistened with alcohol and we use it to wipe the element. some people use disposable chopsticks but I use the ones used for manicuring or a popsickle stick

[Erik Lund]

If you want to see where the fungus or dirt is, use a tripod and, manually focus, shoot several layers of images down though the lens for each surface. Quite easy.

[richardHaw]

If you want to see where the fungus or dirt is, use a tripod and, manually focus, shoot several layers of images down though the lens for each surface. Quite easy.

I bought a blacklight torch for that. unfortunately, it's quite useless and didn't work as advertised