Lens problem?

[Young He]

Hello all,

Sorry if this is not the correct forum to post this in, but here goes. I bought a 9x12cm folding camera at an antique shop earlier today in decent condition, and the lens seems to have haze when I shine a light through it, but there does not seem to be any problem with the image quality actually looking through the lens. The lens looks slightly foggy when I shine a light through it. The lens is a Zeiss Tessar f/4.5 135mm. Can anyone tell me if it is a serious problem or something with the lens coating?Thanks in advance.

 

[BrianShaw]

Most likely no problem at all.

 

[shutterfinger]

Typical buildup on the lens cells from age. 9x12 folder sounds like a medium format camera. A tessar is two air spaced elements in front of the shutter-aperture with a cemented pair behind it.
Removing the front pair or the rear and cleaning the surfaces will likely remove the haze. Removing the front may require infinity focus be reset.
The worst it will do is soften the contrast some.

Light travels the direction of the arrow, typical Tessar design.

 

[Young He]

Thanks for the help. Should I just wipe it with a lens cloth or should I get a cleaning solution? I also never knew that 9x12cm was considered medium format..... Also, how does one go about resetting infinity focus?

 

[BrianShaw]

I’d use a microfiber cloth and dry breath on the outer surface and not worry about it.

 

[Sirius Glass]

Clean with cotton ball wet with isopropyl alcohol, light touch in circular motion. No rubbing.

 

[shutterfinger]

I've had success with a heavyweight microfiber lens cloth and my breath when lens cleaners and alcohol would not phase the haze.
The trim ring on the lens front unscrews allowing the front element to be removed so the surfaces in the air gap can be cleaned. The spacing between the elements must be maintained on reassembly. The trim ring is likely sealed with threadlocker that can be dissolved with acetone/nail polish remover or is very tight and will be difficult to remove.

Infinity focus is set by putting the camera on a tripod, pointing it at a target at least 5000 feet away (the further the better), placing a temporary ground glass at the film plane, turning the front group in or out until the target is tack sharp on the ground glass when viewed with a loupe, then install the infinity stop.
A temporary ground glass can by made by cutting a piece of glass or clear acrylic to fit on the film plane then put strips of Scotch Magic Transparent Tape next to each other without overlapping. The tape side goes toward the lens.
With the camera front closed and the back open you may be able to unscrew the rear group then clean the front by opening the shutter on B with a locking cable release or on T if the shutter has a T setting.

 

[paul ron]

here is a quick n dirty collimeter method.....

http://members.tripod.com/rick_oleson/index-123.html

 

[ChuckP]

If it's on a 9x12cm the focus is adjusted by the camera. My experience with Zeiss Tessar 135mm F4.5 lenses from their 9x12 cameras is that they are very easy to take apart and clean out haze. Unscrew the rear lens group and clean both sides. Unscrew the front group and you with see a cap on the rear. Unscrew the cap. Then clean all surfaces of the 2 front lens elements. Replace the cap and screw the front and rear groups back on. I just did this on a mint Zeiss Maximar 9x12 I bought. Lens look like new now.