I've gotten myself a pancake. That is - a "pancake" lens. There are some camera lenses that protrude a lot from the camera. Then there are a few that are very compact. The one I've got for my camera is the Industar 69 28 mm and it's something like 2,5 centimeters thick. I bought the lens because I was a bit tired of having to use such big lenses with adapters which is what the Pentax K-mount lenses I've used for my camera is.
The lens is not as sharp as the 28 or 40 mm Pentax lens that I've used on this camera. But below you can see that there is nothing wrong with image quality using the Industar.
The only downside to the lens is that it's a bit tricky to find focus in bright sunlight. But that is something that comes with more practice. It did with the Pentax lenses. Besides - the depth of field is quite deep even in dimmer light conditions.
I would recommend anyone to use this lens. It's for LTM (Leica thread mount) or M39 mount rangefinder cameras or adapters. The lens says 28 mm but on my "half-frame" digital camera it has the framing size equivalent to something like a 42 mm lens.
I would recommend you to buy a 'modded' lens from Ebay - they have better close focus range and will focus at 'infinity' which the lens otherwise won't since it is made for a different model rangefinder called Chaika.
Above is the camera with the Pentax mount lens and adapter. It's large!