Lietz Summicron-C M 40mm f2

The No-Contest Bargain Leader in Leica Lenses

The King

Make no mistake about it: The Summicron-C 40mm is the absolute king of bargains when it comes to Leica lenses. Fast, sharp, and super compact. There's so little glass in this lens - A simple formula right in the sweet spot of optical design. Close to the film plane, a symmetric design with a focal length fitting naturally in its physical size. A 10-blade iris keeps defocused highlights smooth and dreamy.

The Filter Issue

My only problem with this lens is the oddball filter thread - While it takes a 39mm diameter filter, the thread density is technically "Serie 5.5", not the typical 39mm filter from you Summicron 35 or 50. You can mount a standard 39mm filter by turning it almost a full rotation before the difference in pitch stops you - It won't damage anything, but I'd use an inexpensive Hoya filter just in case decides to unscrew itself on a crowded bus in Yunnan province. Well, OK, so I have another "issue" with this lens: It doesn't take any of the neat Leica shades. Your only choice is the now 30+ year old collapsible rubber ring that holds the Serie 5.5 filter in place.

Maintenance

After more than 30 years, this Summicron-C needed a little internal attention. I replaced the Leica red dot and restored the engraved lettering.

To disassemble the Summicron-C, you will use a spanner wrench to remove the ring around the rear glass. Similar to the Leitz Elmarit-M 28mm gen-2, there is no index behind this, so once you loosen the ring, the whole optical assembly will rotate freely in the focus mount. This is perfectly OK, because the focus mount remains intact and you simply re-align the engraved markings before tightening the ring again.

Leave the tiny set screw on the front of the lens alone. Removing that will allow the very front of the lens to rotate and unscrew (leaving all glass in place - no harm done). There's generally no benefit to removing this front part of the lens. The f-stop ring stays in place.

If you want to clean and lubricate the f-stop ring on the Summicron-C, you'll spread and then remove the keeper spring that surrounds middle of the optical assembly. After removing this spring ring, you will remove the recessed screw that's closest to the "2" marking. This screw (shown with the arrow here) has a long pin that extends deep down to the iris claw that turns the blades.

The other recessed screw, closest to the "16" marking, should only be backed off, but not removed. The 16 screw is unique to the Summicron-C - It actually controls the pressure of the f-stop detent ball. Tightening down this screw will increase the click-stop action of the aperture ring.

When removing the aperture ring, take care to save the detent ball as it may fall out, though usually the grease will keep it in its hole.

When re-assembling, don't forget that the spacer ring must mounted between the optical assembly and the focus mount.