White spots inside lens

[skírnir]

Does anyone know what the white spots on the inside of this lens is? Initially I thought of evenly distributed dust specks, but can it be fungus?

I was about to sell this lens when I discovered it. The buyer wants to buy it anyway, but what's a reasonable price tag for a Carl Zeiss Planar 1,4/85 with these spots?

I appreciate any help!

B.

 

[sevo]

That is frequently wrongly called fungus or mold - which it is not, at least not primarily. It is a result of condensation: As drops of water that condensed on the inner lens surfaces evaporate and shrink up, they collect the dust from the glass underneath the drop, and as they finally dry, they leave it in a tiny central spot each. It usually takes many iterations before the effect becomes visible in a clean lens - but strong condensation in a dirty old lens can create it in one single event.

The dust may theoretically be spores from fungus - but a growth of fungus would take the shape of filaments or (by the time it is near fruition) woolly spots, and if there is no fully developed fungus itself to be seen inside the lens, it can hardly shed spores. Usually, condensation spots will be general environmental pollution that got sucked into the lens - i.e. mostly soot and other microscopic dust. But it may also contain spores and nutrients for fungus, so these spots might later develop into a starting point for a fungus infestation - so there is a association between (future) fungus and condensation marks.

 

[skírnir]

Thank you for a very helpful reply, Sevo! I appreciate that.
I guess there's no remedy for it, then. Do you have any idea how this will affect the quality of the lens?

 

[sevo]

Thank you for a very helpful reply, Sevo! I appreciate that.
I guess there's no remedy for it, then. Do you have any idea how this will affect the quality of the lens?

YMMV, there are some lens designs that can go all hazy if one single speck of dirt settles in the worst possible spot of some critical internal surface - but that is more likely to be the case in ultra-wides. On a long lens like yours the effect will be very mild, not visible and probably not even measurable as long as the lens is properly shaded - but it will somewhat increase flare, if you use it in flare-prone circumstances.

 

[farlymac]

There is a remedy, but it involves opening up the lens to clean all the element surfaces. Not hard for someone who knows what they are doing.

PF

 

[mikemc_photo]

There is a remedy, but it involves opening up the lens to clean all the element surfaces. Not hard for someone who knows what they are doing.

PF

As long as it is NOT between elements. I also suspect the condensation cycle as noted above, One other possibility is the cement between the elements is starting to dry...Normally you will see odd sized areas with cement issues, I would shoot a test roll at different apertures, should work out fine

 

[thepiecesfit]

It's annoying and sorry to dig this thread up but I have a few spots in my 85 1.2 that just started showing up. This is after paying to have the front element replaced from damage. It's out of warranty now but still annoying that this only happened to this lens and no other lens in the same closet. Is it possible this is also some cement separation of the elements?