If pointing someone to a single "normal" lens as a prime, I'd point them to a 40mm, not a 50. When I work with a 50 (which I very much enjoy; used one yesterday), I find that it is tighter in composition than my normal field of view. The 40 much-better matches my own perception and experience. The 50 is a more-careful tool. 35 is a little wide for me (but perfect for human/photojournalism work). If you want to try ou…
> If pointing someone to a single "normal" lens as a prime, I'd point them to a 40mm, not a 50. The article does have a section on exactly the issue (FOV) you note - it identifies that the 50mm lens is not the same with modern cameras (which have smaller sensors than 35mm film cameras), and recommends a 35mm lens for these cameras. Personally, I have a 35mm prime lens and quite like it, and I think it did help me imp…
That's a different thing, which is about the "crop factor".
Modern APS-C digital cameras have smaller sesnors, with a 1.5 crop factor and will need a 35mm lens to get 50mm angle of view. This is not needed for modern full-frame digital cameras, which can use a 50mm to get 50mm angle of view just like old film cameras.
The article in that section just tells people to get a 35mm for modern (APS-C crop factor) cameras, because that's what gives the 50mm effective angle of view on those.
This issue is orthogonal to the parent's suggestion for 40mm.
To put it in different terms, the article in that section is concerned with "what lens you need on a modern crop factor camera to get 50mm effective angle of view - hence the suggestion for a 35mm physical lens).
Whereas the parent is concened with the actual effective angle of view you get, and suggests 40mm effective angle of view is better than 40mm effective angle of view.
To get such 40mm effective a.o.v, you need a 40mm lens on a film camera or a full-frame digital, and a 27mm lens on a APS-C digital (the kind of cameras the article has in mind when it says that "modern cameras have smaller lensors).