Is this caused by fungus?

[Ariston]

I can see no defect in the lens when looking at it (other than dust), but it is giving me hazy discolored photos in all but ideal lighting. I took a snapshot with it, then with an old AI lens, so you can see the difference. It there just thin layer of smooth fungus that I cannot see, or has a coating been removed, or what?:



Let me know what you think.

Edit: The blurriness is from being handheld at too low of a shutter speed.

 

[voceumana]

How do shots look when they are not pointed into the light source? To me, this looks like flare, which could be caused by a layer of fungus or other surface coating, or just an old uncoated lens.

 

[Ariston]

It looks pretty bad in anything but ideal light. I noticed it first in ambient indoor light with no flash. It is a modern coated lens, Nikon 35-70 f2.8 AF. But I got it used. Looking through the lens with a flashlight I see no fungus, but do see a slight discoloration, I think.

 

[reddesert]

Fungus is often a spidery or spotty pattern on an element that is visible when you look at the lens. You might have haze on an element - this is a sort of more uniform cloudiness. You can try shining a flashlight through the lens from one end while you look from the other and see if one surface is especially cloudy.

 

[Ariston]

Fungus is often a spidery or spotty pattern on an element that is visible when you look at the lens. You might have haze on an element - this is a sort of more uniform cloudiness. You can try shining a flashlight through the lens from one end while you look from the other and see if one surface is especially cloudy.

I have some a flashlight through it. What causes haze?

 

[shutterfinger]

I have some a flashlight through it. What causes haze?

Haze is caused by gassing out of lubricants and some plastics as they age. Hazy lens elements usually clean up easily with one breath and a microfiber lens cleaning cloth.

There is a service manual for the AF 35-70 f2.8 D at http://arcticwolfs.net/
The nice thing about Nikon lens is that you can remove the elements without disassembling the barrel. Lens elements in front of the aperture blades come out the front, elements in the rear come out the rear and may require the removal of the mount ring and aperture control ring. A good lens spanner is necessary.

When shining a light through from one end look at the other end from a side angle as well as straight in. Shine the light in at an angle also. If any paint is missing from inside the light path of the barrel it should be repainted with flat black paint.

 

[kmg1974]

I had one of those zooms. I think it is the glue between two elements that hs gone completely hazy. Shine a bright light through the lens and you will see that a few elements in front of the aperture are opaque, very visible at 70 mm

 

[shutterfinger]

Additional: when disassembling a lens count the number of turns it takes to remove a retaining ring and record it for reassembly.

 

[Ariston]

I actually took off the front element to clean out some dust. I don't know if I am comfortable removing any of the other elements, but I may try since it is just about unusable right now, anyway.

My backlighting example above was extreme, but it is pretty bad with regular ol' indoor incandescent light, too.

 

[StepheKoontz]

I had one of those lenses, it flared like CRAZY. I'm not sure if they all do, mine was unusable in anything remotely challenging. A lens hood didn't do much to help either. IMHO it was way worse that most of the old uncoated lenses I have used. Like you said, even using an LED flashlight, I saw no haze or anything weird going on. Google "nikon 35-70 2.8 flare" and see all the hits on this issue.

 

[Ariston]

I had one of those lenses, it flared like CRAZY. I'm not sure if they all do, mine was unusable in anything remotely challenging. A lens hood didn't do much to help either. IMHO it was way worse that most of the old uncoated lenses I have used. Like you said, even using an LED flashlight, I saw no haze or anything weird going on. Google "nikon 35-70 2.8 flare" and see all the hits on this issue.

Hi Stephe, was flare really that bad? If this isn't fungus or haze, I am shocked that Nikon released such a bad lens. Do you have the 80-200 f2.8 by chance? I was considering buying that lens, but if it is like this too, I will definitely pass.

 

[Ariston]

Okay - I hope everyone is not too busy with the holidays to give me some tips. I took the lens apart and cannot find any fungus or oil residue or anything like that. The glass is smooth. However, setting the elements on my light table I can see a yellow-ish brown color cast - in the rear element for sure, and maybe in the middle set. Is this in the glass, or on the glass? I can't even get it to show in photos for you. Has anyone dealt with this? What can I safely clean it with (although I see no blemish on the glass itself)?

I don't know what to do with this. I have wiped and wiped it with a lens cloth and it sure seems fine, but there is a color cast, and it is making the lens unusable.

 

[shutterfinger]

Have you removed the lens element(s) with the color cast? Its either faulty coating or the cement in a pair. Balsam cemented pairs could be heated to about 250°F to 300°F for 15 to 20 minutes and allowed to slow cool to correct the haze. I do not know if it will work with UV cured cement of not but intense UV light might work to restore it.

 

[Ariston]

Have you removed the lens element(s) with the color cast? Its either faulty coating or the cement in a pair. Balsam cemented pairs could be heated to about 250°F to 300°F for 15 to 20 minutes and allowed to slow cool to correct the haze. I do not know if it will work with UV cured cement of not but intense UV light might work to restore it.

Hmmm, I don't know a lot about lens design. The rear element seems like a single piece, but it is possible it is two put together. I'm not sure how to know - I haven't taken it out of the barrel. I am already afraid I am going to mess up some kind of alignment.

How does heating and cooling correct the haze? I believe you, but am curious how it works if it doesn't remove the actual cement.

It is all nerve-racking for me!

 

[shutterfinger]

Yes there are elements in front of and behind the aperture blades. You know the front is clean and clear so put it back together.
In post 6 I referenced a service manual for your lens, download it if you haven't.

This is the front group, the elements will match the diagram. G1 through G9 are the elements.G3 & G4 are likely a cemented pair; G5,G6,& G7 may be a cemented triplet.

This is the rear group. G10 & G11 are a cemented pair.
Looking through the rear opening in the lens you should see a lens element retaining ring, if its larger than the lens mount then the lens mount has to be removed to remove the elements. With the lens mount off the aperture ring will likely slip off the rear of the lens barrel. The aperture ring will have a spring attached and a click stop steel ball with spring in the edge of the ring so don't bend or stretch the spring or loose the steel ball and spring. The click stop ball and spring are tiny. Item 30 is the lens mount ring. Item 39, rear cover ring will likely have to be removed. NO other parts should be removed from the barrel. Unscrew the retainer rings counting the number of turns and lift them out the rear. Assembly is the reverse of removal.

Canadian Balsam is heat cured/separated. UV cement take a high intensity UV light source to cure and solvents to remove.
I do not know if warming a UV cemented lens will help or not. Balsam will soften with heat and recure with cooling sealing itself to the lens glass which is where the cloudiness is likely coming from or the heat rejuvenates the Balsam.

 

[reddesert]

I don't think a color cast is going to cause the low contrast you are talking about. Haze would. They look very different. Haze looks like a cloudiness in light shined through the lens (I know we discussed this already). With the lens partially taken apart, it should be easier to isolate the location where the haze appears. If you can get to the surface on which it appears, you can try cleaning it.

Zoom lenses can be difficult to take apart and even more difficult to put back together with all the helicals in the correct orientation, so be careful to take notes and pictures.