Originally posted by Michael Piziak Anyone that's read a fair amount of photographic magazines, journals, or websites have certainly come across dozens of articles and 1,001 reasons why the 50mm prime is, or should be, in every camera bag.
Michael, you should always be aware of photo mag fluff or website piffle; just because they keep saying that doesn't make it true. The 50mm lens has been a staple of 35mm photography for historical reasons and it all started with Leica – when Zeiss and the rest weighed in they produced the same recipe of 35mm film bodies with 50mm lenses as the standard package. I presume 50mm was chosen because it gave a useful angle of view without being too difficult to design and make. Fast forward to the heyday of 35mm film cameras and they all came with, or offered a choice of 50mm or near-50mm lenses. Canon, Nikon, Pentax, Contax, Yashica, Minolta, Leica, you name it, they all had a 50ish standard lens, even the Soviet era Zenit-E with the 58mm Helios.
Some say the fifty most closely approximates the view of the human eye, but that's a simplistic answer to a complex question: we can see much wider than 90 degrees but what our attention is on might occupy only a few degrees. Try this – stand 30 feet from the back of a car, look fixedly at a brake light and try to read the number plate: you can't do it, but a 50mm lens on film or full frame easily resolves both in a single photo. Alternatively, try photographing a clear, moonless night sky with a standard lens and you'll get a disappointingly narrow section of the expanse your eye easily appreciates.
In film days I carried a bag with 24, 35, 50, 105 and 200mm lenses for my Spotmatics but the lens I used most was easily the 35mm, the least used was the 50. Nowadays I shoot APS-C and although I have a film-era 50mm f/1,7 SMC-M in a corner somewhere, it's hardly ever used since it's usually not wide or long enough for what I look at to photograph. I keep it in case I want to focus pretty close, but I generally wouldn't miss it if left in the cupboard. The 35-105 A is easily my most used lens, often at around 70mm.
Some photographers love the fifty, others don't, and buying a lens because a magazine says you must have one is silly. We don't all concentrate our efforts on bokeh-filled portraiture, so we don't all have 85mm f/1.4 lenses, do we? Nor do we all leave a 12mm ultrawide permanently fixed to capture another epic ultrawide puddle-and-mountains-at-sunset image. Get the lens you have a use for.