Zeiss Ikon 521/16 cloudy front element cleaning

[Alex's Camera]

I've recently received my great grandfathers Zeiss Ikon Ikonta 521/16, with at Novar-Anastigmat lens, which works well, but has a very cloudy front element, I've read online that I should wipe the front element with household fungicide, or hydrogen peroxide, but I've not found any resources about removing the front element at all. How do I remove the front element of the lens? Thanks, Alex

 

[thuggins]

If it is like my Nettar (and many/most other folders), remove the focus ring by loosening (not removing!) the three set screws, then unscrew the element. I have had good luck using ethanol to clean haze. It is doubtful that a fungicide or H2O2 would have much impact on haze for, as has been pointed out here many times, haze and fungus are very different things.

 

[Grytpype]

The easiest way is to take out the focus-stop screw from the focus-ring. Then you can unscrew the front element without having to re-set the focus after reassembly. First, note at the infinity setting roughly how much gap there is between the back of the focus-ring and the shutter body, then, when you unscrew the element, note the position where the helical separates. When you reassemble, start the screw in the same position it separated, and when you screw it in to the same depth it started, you should find the hole for the focus-stop screw in about the right position.

When cleaning the back of the front-element you need to be very careful not to spread helical grease on to the lens. The best liquid to use for cleaning is lens-cleaner, but If that does not touch the haze I'd try isopropanol or naptha (lighter fuel) or, as a last resort, acetone (but keep it away from any painted surfaces). If there is fungus, ordinary vinegar will remove it.

If the helical needs re-greasing it is best to remove the three little screws to remove the focus-ring from the front-element, because you cannot get at the helical properly otherwise, but you will then need to re-set the focus.

If you need to clean the other lens elements, you will already have access to the front of the second element. If you take out the rear element (normally quite easy), with the shutter and aperture open you can get at the rear of the second element.

Good luck!

Steve.

 

[Ian Grant]

One problem with the early Novar lenses on these cameras is the optical glass used for the front element was quite soft, the same glass was used in some LF Tessar lenses and the Leitz Summar. The element is more prone to scratches/cleaning marks but can also suffer from atmospheric pollution etching the surface. I have a 520 which was the earlier 6x4.5 model and while the lens looks clean with no scratches it has very low contrast.

I have a 75mm Novar off a Super Iknota in front of me and it's even worse the front element has soft reflections, what some refer to as cloudy, and the lens is very low contrast, the shutter works perfectly at all speeds. I bought it from a Camera Fair with a bunch of shutters, all had come from a camera repair workshop that had closed. Luckily there was also a new 75mm Novar (coated) in a Prontor shutter, never been fitted to a camera, so I can fit that to my 520 if I get around to it.

The worst lens I've seen with this issue is a Meyer 50mm Domiplan that came with an Exa, the etching of the front element is so bad it won't actually focus an image yet the lens barrel look like new.

Ian

 

[mgb74]

The easiest way is to take out the focus-stop screw from the focus-ring. Then you can unscrew the front element without having to re-set the focus after reassembly. First, note at the infinity setting roughly how much gap there is between the back of the focus-ring and the shutter body, then, when you unscrew the element, note the position where the helical separates. When you reassemble, start the screw in the same position it separated, and when you screw it in to the same depth it started, you should find the hole for the focus-stop screw in about the right position.

...

Your measurement of the shutter to focus ring gap has to be within the "margin" of the thread pitch. Correct?

 

[Nodda Duma]

One problem with the early Novar lenses on these cameras is the optical glass used for the front element was quite soft, the same glass was used in some LF Tessar lenses and the Leitz Summar. The element is more prone to scratches/cleaning marks but can also suffer from atmospheric pollution etching the surface. I have a 520 which was the earlier 6x4.5 model and while the lens looks clean with no scratches it has very low contrast.

I have a 75mm Novar off a Super Iknota in front of me and it's even worse the front element has soft reflections, what some refer to as cloudy, and the lens is very low contrast, the shutter works perfectly at all speeds. I bought it from a Camera Fair with a bunch of shutters, all had come from a camera repair workshop that had closed. Luckily there was also a new 75mm Novar (coated) in a Prontor shutter, never been fitted to a camera, so I can fit that to my 520 if I get around to it.

The worst lens I've seen with this issue is a Meyer 50mm Domiplan that came with an Exa, the etching of the front element is so bad it won't actually focus an image yet the lens barrel look like new.

Ian

The Summar and Domiplan both used Schott SK16 for the front element. The Novar either used SK16 or SK10 for the front element (best as I can tell).

These are both Short-Crown glass with index above 1.6 and dispersion around 57-60. They all share the common trait of awful stain resistance (optical shops consequently have to be very careful how they polish these glasses). This is the underlying reason for the problems you saw. In modern lenses the glass is better protected by modern coatings, but back then they weren't and could easily stain from exposure to outgassing of the surrounding materials (painted wood, treated leather) during storage. I avoid the use of SK-family glasses for exposed elements when at all possible.

Unfortunately, once stained there's nothing you can do to fix it except pitch the lens and get a new one.

Cheers,
Jason

 

[Grytpype]

Your measurement of the shutter to focus ring gap has to be within the "margin" of the thread pitch. Correct?

I said "roughly" so that, assuming the helical was reassembled at the correct position, it would act as a simple check that it did not need to be screwed in by another 360°. If you measured more accurately, of course, it would also confirm that you had the helical assembled at the correct 'start' (I think there are three).