Fungus

[Frank R]

How does fungus on a lens affect the picture?

I have a medium format folder that has fungus on the middle element of its triplet lens. I was surprised at how good the photos turned out from the first roll. I could not detect any affect from this large fungus bloom that covers a third of the lens. Would it only show up if I enlarged it?

I have a 11 3/4 inch Heliar that has some fungus too.

How about lens separation? How does that affect the picture?

 

[Donald Miller]

Most usually, one can assume that anything that compromises the optical path will be apparent at some degree of enlargement when compared to an uncompromised optical path.

Fungus does etch glass from what I have been told.

Now that being said, I can not say that your equipment will not meet your criteria for an image...only you can decide that.

 

[AgX]

I guess! the more simple a lens is constructed (calculation, grinding, coating, barrel construction, aligning etc.) the less visible the effect of fungus and other after-manufacture deteriorations would be amongst those effects inherent to the lens from the begin.

 

[ath]

Contrast will go down as the fungus scatters the light. Transmission will go down also.
Basically, if it's in the middle of the lens, is is roughly in the plane of the aperture and thus will have very little effect on sharpness.

You can view it from the other side: the fungus will open up the shadows making your film apparently more sensitive.

 

[seawolf66]

Frank R. Post a foto of said lens with fungus , I just took apart a lens with what was thought to moisther and fungus but It clened up real nice:

 

[Frank R]

I tried cleaning it off but it did not come off at all.