How does fungus affect image quality ?

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Spyderman

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I've got this Oly Zuiko 50 "Made in Japan" lens with fungus behind the front lens element. It's probably already dead, as I've given it a good dose of UV radiation, but I'd like to know how will it affect image quality of the lens.

Unfortunately on this lens, the front element is pressed in the plastic holder together with the other 2 in the front half of lens (no, it's not glued with balsam, it's just pressed). Older versions of this lens use aluminium retaining ring and the front element can be removed for cleaning, but not this last "Made in Japan" version.

BTW: it seems that by pressing the elements in their plastic holder, Olympus could manufacture the lenses with tighter tolerances and thus the "Made in Japan" lenses have the reputation of the sharpest of the Zuiko 50/1.8 family.

So, back to the original question: How does fungus affect image quality ?
 
Spyderman, have you tried it yet? easiest way to find out is use it! I have a zuiko 50 with a lot of rear element fungus and has no effects that I can see in real photos. Front element fungus probably affects even less! If you want to test this, grab a felt tip pen and draw on a filter a criss cross pattern, fit filter to lens and you wont see it when looking through finder! All I can see is that it affects the contrast of the lens. You really do need to cover the surface a lot to have this affect show though.
 
Glad I read this. That's good info. I have a Zuiko 50mm f1.8 with mold. I plan to have it cla'ed since it has sentimental value, and it does not cost very much at zuiko.com.
 
I'm worried that it could spread. I think we have covered this on RFF a lot, but my brother had to throw out a bunch of gear when a fungus made it's way thru his collection.
 
I have spent a lot of time in tropical climates where fungus is pervasive and photogaphers must use all all sorts of methods to try and stave off fungus. Small bits of fungus may not affect a lens performance much but believe me, any serious infestation will decrease contrast and sharpness, even making for a "dreamy" effect. For some reason, Nikon glass seems particularly suceptible. I recently had the fungus removed from an old 35-70 2.8 Nikon zoom lens. Some of the fungus was able to be cleaned but an internal glass element had to be replaced. In any case, the quality of the images this lens produced after the erradication improved dramatically. Sure zoom lenses have a lot of elements but I've seen the same before/after results from fixed-focal length lenses.
 
Fred's advice is sound, also if you live in a humid place do not store lenses with caps on, and store them where they get light if possible.
 
Ok guys, I will concede that painting black paint onto the front in as big spots as this will have an effect when at f22. How many times has anyone seen fungus that looks like this? Soon as you open up the effect on pics is not there. Now back to the original question, what effect will fungus have on pics?
If its black paint or marker like and big, then yes it will have an effect if stopped down, if it's like any fungus i've had or seen and not covering the majority of the element then not a lot.:D
 

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Syderman,
The front of the lens can be removed. I have done several. It is a touchy job to get the name ring out. The glue is tough to get free of.
 
What is being suggested by Nobbylon is similar to what photographers have been doing for years to get photographs through barriers; such as bars at a zoo. You are focusing them out, using a combination of focus and aperture. You can watch that occur in the viewfinder of an SLR. You can usually also, if you move up to the bars and get between them, notice a difference in the viewfinder, between the bars or no bars. You can see a difference in sharpness. How much will depend on the FL of the lens, and closeness to the barrier. There will be degradation.
 
Syderman,
The front of the lens can be removed. I have done several. It is a touchy job to get the name ring out. The glue is tough to get free of.
Click to expand...

My dear Whisper - I've had the nameplate out, even the whole front half of lens elemsnts. It can be removed and then you can access diaphragm blades. And it's as I said: on older Zuikos, it seems the front group can be disassembled. On the later versions it's pressed together (i.e. the 3 front elements, not the whole lens)

the fungus is on the back side of the front element. There's not much of it. In some spots it extends from the edge about 1 cm to the centre, but it's only thin spider-web-like thing.

BTW: my GF has already shot one film with it and the Olympus metal lens hood for this lens, and the pictures look good (I mean I can't see any effect of the fungus). It's possible that the contrast is lower, but I can't confirm that, because it was only my second film that I developed myself.

Now just a hypothetical question: which is better in your opinion: older SC (less sharp) lens w/o fungus, or newer MC (supposedly sharper) with fungus ?
 
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