M System goodness, my normal lens. No not a nifty fifty but rather the semi-wide alternative preferred by many, the 35mm. The one most often to be found attached to my Zeiss Ikon camera body.
So I am about to get myself into hot water here, but... here we go. Everyone knows that the 50mm lens is the standard lens for full frame digital and 35mm film (135 format) right? Yes, that's right. Why? Because that's the focal length whose angle of view matches that off the human eye right? No. that's wrong.
What? Typically, to match the human eye, for the FF and the 135 formats the standard lens should be around 43mm. This might explain why those clever people at Contax made their standard lens for their G series cameras (G1 and G2) a 45mm.
But we need to be careful. With a 43mm lens on full frame digital and on a 35mm film frame, it sees the world “undistorted” so objects projected on to it are the same size and shape as we would see them. However, the 24x36mm frame is a “crop” of what the human eye can see because sensor/film-frame isn’t round and fits" inside" the sphere of photo receptors that wrap around the back of the eye.
Thus an eye has a wider field of view, all round, than the 43mm lens projects onto the rectangular 24x36mm frame thus we see much more than just what the camera does.
So here is the dilemma. A 50mm is actually too long to project images at the normal size on the 24x35 frame so we can see that is 43mm should actually be called a normal lens, which clears ups some terminology. This foreshortens the field of view of the eye even further too.
Which brings us to the 35mm lens. This lens, being a semi-wide, opens up the field of view for the eye making comfortably closer to what it actually sees at the expense of making the subjects in the 24x36 frame a bit smaller than normal. It's a short compromise in the other direction but a more natural one to me.
So why did we end being stuck with the 50mm standard lens in the first place and not a proper 43mm? Simple, Oskar Barnack who invented the first 35mm camera needed a lens to put on the front of it and the only one available to him at the time was, you guessed it, a Leitz 50mm f3.5 and the rest as they say was history.
Oh, and as you ask, mine is a Leica 35mm f1.4 Summilux-M Asph. This is a lens that I will never part with.