Sigma 180mm f/5.6 APO

[caspert79]

Just received this lens I bought very cheaply from Japan. It has 2 really tiny fungus spots on the rear element that don't seem to appear on the image. It's now in my UV-C sterilizer, so the fungus will probably be killed and prevented from spreading further. The notorious sticky coating on the lens barrel has already been thoroughly removed by the former owner, which is a plus.
There is a MF and an AF version of the lens. I have the AF version, as the MF version is very hard to find. I use it with a manual MAF-Sony E adapter. Build quality is better than expected. Main advantages of this lens are that A) the lens is super tiny for a 200mm-ish lens, B) it has APO performance and C) can focus real close. It seems to be a great tele for traveling. Took a few shots around the house, and the results are quite promising IMO!

Click for full size.

SIGMAAF18056APO_1 by devoscasper, on Flickr

SIGMAAF18056APO by devoscasper, on Flickr

[Dejan]

It's a pretty sharp and versatile lens (it performs pretty well at infinity as well, and it's easy to carry around). I enjoyed using it. The build quality is the only issue I had. Of course, I'd prefer it to be F2.8 or something like that; but then the size and weight would be quite different. I'd say it's a lens for those who really know what they want, so they are fine with 1:2 mag. ratio and slow speed. I liked the overall rendering too. The bokeh and colours are really nice, and sharpness won't be an issue...

[alex_d]

"..UV-C sterilizer," - what is this things, self made or a ready product?

I use to take a sun bath with lenses from time to time ...

[caspert79]

It’s basically a box with uv-c lights and a mirror on the inside, meant to sterilize toys and other stuff.

[caspert79]

[BrianSVP]

Honestly, there's absolutely no point to UV sterilizing a lens like this since a) if the lens is stored properly in dry conditions, the fungus will already be dead anyway and will not spread further, and b) the spores that cause fungal infections are ubiquitous in the air, and there's no such thing as a truly hermetically sealed camera lens, at least for anything vintage sold to end users. Even if you've managed to destroy the spores in a lens at any given time, it will draw more in it the moment you use it again.

Furthermore, the contention that lenses can "infect" each other is a myth as well. If multiple items stored together all develop fungus, it's not because fungus has magically jumped from one to another but rather because they're all stored improperly, and fungal spores in the dust already present in the lenses have become active due to environmental conditions conducive to fungal growth. In fact, putting lenses together in a bag makes it less likely that spores will spread from one to another, since there is little air circulation to carry the spores from place to place.

This is all information I have first-hand from a Cornell-trained PhD mycologist, whose opinion I respect quite a bit.

[stevemark]

[mr_tibbs2004]

[RokkorDoctor]

[caspert79]

[visualopsins]

There is a difference between a fungus spore murdered by exposure to UV light and a dormant fungus spore. One provides the scaffolding for new spore growth when conditions are favorable. One continues to grow when conditions are favorable.

I've also heard favorable conditions 70% humidity for three days. And I've heard powdery mildew crop infection occurs when ambient temperature drops to below 40F.

[alex_d]

ok , not aware of toy uv-c 'cleaning' light, but i get the concept.

the sun is highly effective.
when it shines.
and while is still for free.
but it looks like not for long.

[caspert79]

Stack of 5 images @ f/8 (click for full size):

2024-01-29 13-07-53 (B,R8,S4) by devoscasper, on Flickr

[stevemark]

[blotafton]

[cyberjunkie]

Can you please post a picture of the lens the way it is today (after being stripped of the sticky plastic layer)?
I have in mind to do the same to my example. So I'm curious to see how it would look.
I have the same lens in PK mount (manual focus) that I bought new when the lens was released. It is one of the VERY few lenses I ever bought new.

Cheers

Paolo

[caspert79]

[RokkorDoctor]

Are you sure that lens ever had a sticky coating? As far as I know SIGMA applied their screen printing on top of the ZEN soft-touch coating, so if you remove that sticky elastomer coating the screen printing would have been removed as well.

Unless at some point they changed to applying the screen printed markings first, and the ZEN elastomer coating after.

[caspert79]

[cyberjunkie]

I have the Manual focus version, and mine developed the tackiness after years and years, when I decided to put the lens inside a new wooden chest that was still smelling (I guess the paint was not water based!). I believe that if had kept the lens in a place with some aeration it could have avoided getting sticky, cause the phenomenon happened at least 20 years after I bought the lens.

Regarding the serigraphy with all the diaphragm and focusing references, in my example it definitely is ON TOP of the surface plastic layer (ZEN finish).
Stripping one would also mean strip the other.
I had in mind to try some cure, but I had to clean the fungus first, cause that dammit chest attracted humidity and a few lenses got infested.
Now it's partially cleaned, and I might attempt a cure. I have in mind one of the spray fixatives that are sold in art stores. They are used to preserve drawings or other kind of paintings.
What do you think? Any other possible solution?

[caspert79]

If you’re removing a layer that actually holds the painted indications, I can’t think of a way to preserve those. The question is: do you really use? I know I hardly do.

[RokkorDoctor]