Lens haze - What cause? Is that that bad?

[pluton]

I have a 35/2.8 "New Nikkor" that developed some kind of haze on the outside of an element inside.  Again, it was fairly even and dense, not looking like the usual stringy fungus.  That also lost a lot of contrast and quality.  But because it's the lens it is, I opened it with little more than bare hands and easily cleaned it up with plain old isopropyl alcohol and a slightly used sensor swab.  I don't worry too much about the permanence of this fix, since it's so easy to do again.

This exact thing happened to my 2 35/2.8 K/Ai lenses about 20 years ago.  I used a commercial lens cleaner ("Panchro") which is, apparently, mostly isopropanol.  The lenses haven't refogged yet!

[Zang]

Thanks all for your responses...

In the most angles of view, the element looks perfectly clear:

[Zang]

In some specific angles of lighting/viewing, you can see some areas reflecting the light differently, they appear to have hazy reflection:

[Zang]

...I marked the areas for easier viewing

[Birna Rørslett]

I would suspect early fungus, based on these pictures.

[Zang]

I would suspect early fungus, based on these pictures.

I know it is really hard to examine this by looking at the picture. These things seem to be very slightly reflective areas. When I change the angle of view just a little, the blotches disappear and the glass look clear. Even a magnifier did not show anything on the surfaces of the element. I still suspect these are coating damage caused by excessive cleaning or some very thin residue of oil (on the inside side, if it is oil).

[Birna Rørslett]

The spots had a whitish appearance. Never bodes well in a lens.

[Zang]

Good to know. Thanks Birna.

[Zang]

For the first time, I took the lens for a test ride. I know the lens is not designed for portrait, but that was what I bought it for, mainly. The contrast and sharpness are incredible. Picture was taken hand-held in pretty low light, low contrast lighting and I believe it was 400 ISO, Sony Nex 6.

[Zang]

Almost two years went by guys, but I have good update. I did not use the lens much in the period of the last two years. Today, I took it out and guys, those blotches are all gone. The glass is crystal clear. I know I said the blotches seemed to be on the external glass surface but you know that it is sometimes confusing where they actually are. My best guess is, they were from internal evaporation which evaporates again and away from the glass in dry condition.