One lens forces you to design and make that one lens work. In time you start seeing the world as the lens does, it happens rather quickly. When you have an option, you will doubt the choice and stop and change lenses. Often loosing the moment.
The one lens makes you work a little harder. I have often been rewarded by this method. You see in terms of that one lens.
Peter
I could not agree more!
Beyond that, it varies/varied with format. On 135 flm I would use 135mm for headshots and 35mm for full-length fashion. Quite often, during the 60s, we would use 35mm for half/lengths too, which gave a distortion, an elongation to heads at the edges of the frame, which was graphically novel for a while, but hardly flattering. Seek out some of the many relevant Penelope Tree shots by Bailey to get the idea. I don't think he was doing that with Shrimpton!
Were I doing commercial work today, fashion and calendars would see me using 300mm and my 500mm reflex a lot more than I used to use 'em. But the point about that is all about an interest in "look".
Today, old, not terribly fit and also very much retired, if taking a camera walkies at all, I would not dream of leaving home without a single lens already fitted. Photography is no longer about making my living, but amusement. Why play at mules and Nat. Geog. stars on a three-month trip? Use that single lens choice to its best advantage and be surprised at how quickly you discover photographs are about you, not equipment. You have a better chance of learning that if you keep the lens pretty wide open. Stop down until all is sharp, and waddya got? Confusion.
On 120 fomat (6x6) I used the 80mm for studio full-lengths and the 150mm (180mm when I had one) for portaits and some full-lengths when I wanted less background. I would not go walkies with a big camera, ever again.