Is this fungus in my lens?

**ProfessorBuzz** · 01-09-2021, 06:33 AM

Balsam separation starts at the edges between two optical elements that are joined together. Fungus will show up usually on the outward (Front) and inward (back) surfaces where fungus spores land and make a home. Fungus can't get between elements cemented with Canada Balsam cement unless the cement starts to degrade and separate.

A couple articles for you:
What Is Balsam Separation And Can A Lens Be Repaired? | Outside The Shot
Repair: “Shneideritis” & Edge Separation | Richard Haw's Classic Nikon Repair and Review

Jonathan Mac · 01-11-2021, 09:13 AM

It seems about 50/50 between fungus and balsam separation. At least with the latter I don't have to worry about it spreading to other lenses.

I need to do some more testing on APS-C but for the small amount of use it'll get on film I think it's probably not worth returning.

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01-09-2021, 06:33 AM	#16
ProfessorBuzz Loyal Site Supporter Join Date: Feb 2018 Posts: 1,903	Balsam separation starts at the edges between two optical elements that are joined together. Fungus will show up usually on the outward (Front) and inward (back) surfaces where fungus spores land and make a home. Fungus can't get between elements cemented with Canada Balsam cement unless the cement starts to degrade and separate. A couple articles for you: What Is Balsam Separation And Can A Lens Be Repaired? \| Outside The Shot Repair: “Shneideritis” & Edge Separation \| Richard Haw's Classic Nikon Repair and Review

01-11-2021, 09:13 AM	#17
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,897 Original Poster	It seems about 50/50 between fungus and balsam separation. At least with the latter I don't have to worry about it spreading to other lenses. I need to do some more testing on APS-C but for the small amount of use it'll get on film I think it's probably not worth returning.