Fungus or balsam separation?

connloyalist · Joined: 22 Jul 2020 Posts: 248 Location: the Netherlands

I would like to take advantage of the wisdom collected in this forum Smile

Yesterday I received a Soligor 100-300mm /f5 C/D (see: http://forum.mflenses.com/soligor-100-300mm-f5-lense-t14583.html). The front element has some issues of which I am not entirely sure whether it is fungus or balsam separation. According to the optical chart included with the lens the front two elements are bonded, which makes me suspect this is balsam separation.

What do you think:

Regards, C.

Oldhand · Posted: Wed Aug 11, 2021 10:05 am Post subject:

Looks like thread fungus to me, but it could be growing between the elements.
If you can remove the front pair of elements, you will soon see if it is between or on the back of the second element
Tom

D1N0 · Joined: 07 Aug 2012 Posts: 2495

Unlikely it is Balsam. Looks like fungus. That is a Tokina made lens. Here is the Diagram of the Vivitar version (Pentaxforums.com)

Front element is single and the 2/3 is a group. Just get out the front element and clean it.

connloyalist · Joined: 22 Jul 2020 Posts: 248 Location: the Netherlands

Interesting that the (or: this particular) Soligor version apparently is different from the Vivitar one. This is the info included with the lens. The serial number matches the lens. Note that this shows the two front elements being bonded, as well as this being 12 elements in 9 groups as opposed to the Vivitar which your info proves as being 13 /9:

With lenses that have fungus I take the precaution of not storing them with my other lenses, so to be safe I will put this one in a different place.

Regards, C.

D1N0 · Joined: 07 Aug 2012 Posts: 2495

Definitely a different, probably older design. Likely related to the Soligor 75-260mm 1:4.5. Mine weighs 1128 grams with caps. A larger more metal lens than the later Soligors. Still I think the fungus is likely on the rear of the front group.

connloyalist · Joined: 22 Jul 2020 Posts: 248 Location: the Netherlands

Thank you all, I will assume this is fungus. With lenses that have fungus I take the precaution of not storing them with my other lenses, so to be safe I will put this one in a different place.

Regards, C.

Alun Thomas · Joined: 20 Aug 2018 Posts: 632 Location: New Zealand

I've seen versions of the Soligor C/D 100-300mm F/5 with either a 62mm or 67mm front filter thread, apart from which they look very similar. Perhaps you can get the lens in either of the two optical versions seen on the two different diagrams, the 67mm heavy version would appear to be the earlier one, with the trend being toward lighter lenses in the early 70s. My version was the 67mm version. It was a difficult to take apart from memory

Zamo · Joined: 08 Feb 2019 Posts: 163

Looks like fungus on the surface of an element, not between cemented ones (in this case, they probably should grow from the sides towards the center, not finding them so much into the glass, and with a big spot with no connection to the sides). If it is between the cemented glasses... then you can probably forget about cleaning it.

Lightshow · Joined: 04 Nov 2011 Posts: 3669 Location: Calgary

Proximity does little to stop fungus from infecting other lenses, the spores are everywhere, it's the conditions that the lenses are stored in that really matter, too much humidity and not enough air circulation are major contributing factors.

If you can't get around to cleaning the lens asap, then place the lens in the sun so the UV light can kill the fungus, but know that there could be damage happening still from the acid the fungus produces, but at least the fungus will stop growing where the UV can reach it.

Slalom · Joined: 10 Dec 2017 Posts: 151 Location: Stourbridge

Have you tried UV, I found a pair of uv Torches on Amazon I think.

Get two sheets of card, cover one in silver foil, cut a hole in the second and silver foil so the hole remains. then stand he lens on the solid card and rest the other card on top, balance uv torch over hole and switch on.

kymarto · Posted: Fri Aug 13, 2021 1:10 am Post subject:

Knudsen · Joined: 16 Jun 2021 Posts: 115 Location: Indiana

kymarto · Posted: Fri Aug 13, 2021 5:03 pm Post subject:

As long as fungus is exposed to light it is dead. Normal room light is enough. Sunlight is definitely enough.

visualopsins · Expire: 2025-04-11