Zeiss Planar 50mm 1.7 front element/group fungus mark

Thomblrr · Joined: 17 Jun 2019 Posts: 8 Location: United Kingdom

Hello, this is my first post so I'm sorry if it's in the wrong place. I got a Zeiss Planar T* 50mm 1.7 cheap due to fungus - I've cleaned almost all of it off but there's a tiny bit that appears to be inside the front element group, which I can't separate.

I'm surprised that these expensive lenses would have elements glued together, but I can't see any other way that this could be caused, unless it's been etched?

You can see the mark on the bottom edge of the element, where the lamp reflection appears purple.
http://imgur.com/sOj7Gwu

Any suggestions or tips would be really appreciated.

Sciolist · Expire: 2021-04-16

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

Yes, it's most likely coating damage and, since this fungus is between glued elements, there's really nothing you're gonna be able to do about it. But take heart. You picked up an excellent, expensive lens for cheap -- and what tiny amount of fungus there is that remains will not affect your images at all.

If the fungus is still alive, you can kill it just by making sure your lens is exposed to sunlight. So, take it outdoors on a few bright, sunny days, and thoroughly use it. That should take care of the fungus for good. And, in the future, make sure that the lens is kept in a dry environment and that it sees sunlight from time to time.

Welcome to the forum!

aidaho · Joined: 29 Apr 2018 Posts: 456 Location: Ukraine

I'm fairly sure this spot does not contribute to the in-focus projection on the sensor.
You likely won't even see it in the bokeh-balls, where it's has the best chance of appearing.

There are lenses with more or less guaranteed peripheral coating damage of some degree from the retaining rings, but it does not manifest itself anywhere in the final image.

Thomblrr · Joined: 17 Jun 2019 Posts: 8 Location: United Kingdom

Wow, thank you for so many helpful replies so quickly.

http://imgur.com/ITNG1Oh
http://imgur.com/hD96OgJ

Here's a couple more photos courtesy of the backwards lens macro technique!

I'll make sure it sees some sunlight and just shoot with it anyway then - just need a nice contax now...

visualopsins · Expire: 2025-04-11

Definitely threads of fungus. Right, there should be no effect on images; you might see it in wide open bokeh highlights; stop down to remove use of the outer portion of the front element when image-making.

Zamo · Joined: 08 Feb 2019 Posts: 163

I have a Pancolar 50 1.8 with a bit of fungus in the sides, in the middle of two glued-together glasses. Impossible to clean, but does not affect pictures at all, and I have used it under all possible circumstances.
Small advice: when exposing it to the sun to kill it, don’t bake it! If it gets too hot the oils inside it can become too fluid and move where they should not be. Just natural light is ok.

aidaho · Joined: 29 Apr 2018 Posts: 456 Location: Ukraine