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Repolishing & re-coating a SUMMAR f2 front optic

Before re-grinding/polishing can commence

Nearly every Summar F2 lens I have seen has marks on the front surface of the front optic. The results from these lenses is very 'romantic' . They have very low contrast and the focus is so soft that it appears that you have been taking photographs in a mist. This can be desirable in certain instances , but to improve performace of the lens the only remedy is re-grinding and re-polishing the front , steep , surface of the front optic. The SUMMAR glass is softer than normal Leitz lenses and constant wiping with a cloth over many years leaves the surface pitted with tiny scratches . This abundance of fine marks disperses light entering the lens and the consequent result is similar to putting vaseline on a lens to give beneficial , enhancing results as in portrait photography. Before the lens can be restored the front lens element has to be removed from its mount. The glass is pressed into a brass mount and the edges 'peined-over' to secure it . After it is finally removed the optic is measured optically on a test-glass plate and a moire pattern obtained. It is then machine ground and polished before being coated with a broadband magenesium flouride anti-reflective layer . LEICA
LEICA Re-polishing/Coating the front element on a  Leitz  Summar Lens

Restoration of the Summar lens front element

The first job :   

removing the front element


















Component Parts

The four parts Optic , ring , grub-screw & mount .

The 'grub-screw' in the front ring between Wetzlar & Summar is removed and the front complete with optic can be removed.







The glass element is fitted into the chrome-plated brass mount with a packing ring and the edges of the mount are 'peined-over' to secure the optic. To remove the glass it is necessary to turn-out the edge of the mount and remove sufficient metal to allow the ring & optic to be removed. It is then heated to 200 degrees C to soften the cement . When   hot  , the glass is pushed out from the front.




With the glass separated from the mount it is now possible to re-grind & POLISH THE FRONT SURFACE , then , after checking the curvature it is re-coated with magnesium flouride in a vacuum chamber .


summar.GIF (15353 bytes)
Summar front elment
It is a simple matter to remove after unscrewing the grub screw

lathe.GIF (118404 bytes)
Turning out the optic
It is necessary to remove the metal sufficiently to allow the separation of of the element from the mount.

sum_ex.GIF (43117 bytes)
The four parts of the Summar front optic
The lens is heated to 200 degrees C & the optic & retaining ring can be pushed out.

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