Sonnar disassembly

[argentum nitricum]

Hello everyone. I would like to clean the front lens of a Sonnar 50mm f2 collapsible with the bayonet for Contax IIa: can anyone suggest me how to disassemble it?

 

[BrianVS]

https://www.flickr.com/photos/90768661@N02/?

The optics module is held into the collapsible mount with a retaining screw- remove it, module unscrews. Be careful of the shims- some are 0.02mm foil. Once the optics module is out, MARK the orientation and position of the variable retaining ring that the shims sit on. Scribe an arrow to show position so you put it back on with the same orientation. Then remove the link screw between the aperture ring and mechanism. Once off, you will see the set screws that hold the front filter ring in place. With it out, the glass held in brass fixtures can be taken out.

 

[Trask]

There's been a recent thread on exactly this topic:

https://www.photrio.com/forum/index...eiss-sonnar-5cm-f2-collapsible-anyone.123249/

BrianVS: nice photos of your disassembly on Flickr. One question: where are the aperture blades? I don't see them in any of your photos. Are they accessible for cleaning and relube?

 

[BrianVS]

The rear module simply unscrews from the barrel, front glass is out in this picture.

Aperture Blades:

CZJ 5cm F2 Rigid by fiftyonepointsix, on Flickr

Always best to leave them in the wide-open position while doing work. They are in the barrel, shown on the right. For Flood Cleaning: use a small screwdriver to open them back out. I use Ronsonol (Lighter Fluid) to flood clean them.

 

[BrianVS]

Different Sonnar, a 5cm F1.5:

RIMG0421 by fiftyonepointsix, on Flickr

But the F2 will be the same.