Truth is, while rangefinder lenses from 12mm to 135mm are easily available, folks often travel light with a rangefinder - one lens on the camera, just maybe another in a pocket.
I wondered what lens is that number one lens - and more important, WHY #1 - for various folks here on the forum.
When I first started shooting professionally, like many journalists I stuck to the 35mm lens. Then one day Burk Uzzle and I switched cameras to take pictures of each other. That way we each ended up with pictures of ourselves on our own film (not too egocentric). I picked up Burk's camera and yelled, "What is this lens?" It was, compared to what I was use to, a modest telephoto. It might take a little more effort to compose an image compared to the "get it all in" 35, but that very effort could make for a better, stronger picture. Burk said, "It's a normal; it's a 50." From that day on, I was a 50 user. Now, with the M8, I use the 35 as a normal. But someone (and please check in a give yourself credit) pointed out that the safety margin in the bright line finder of the first M8 actually made a 40mm lens (which brings up the 50mm frame) frame line a good choice and more accurate at normal distances. It works out to the equivalent of a 52mm lens on the 1.3 frame M8. I've ordered one from Cameraquest. And I hope it will be my new "normal" on the M8.
Once again, what's THE lens on your camera when you head out the door and WHY?
Bill