Quote - I believe (and my get corrected) that the raw Poser Focal Lengths are for a 35mm film camera. At least, this is how it looks to my eye... and I own both 35mm and 2 1/4 square cameras.

 

That is how I understood the focal lengths and I started photography many, many years ago.  When I started, most cameras, the 35mm at least, came with a standard 50mm lens.  It is less than a norm these days as the introduction on digital cameras, with different sized image capture devices, has meant the focal length needs to be adjusted accordingly.

As to what focal length should be used, well it can vary.  Fot instance when I was doing portrait photography I often used 135mm as this meant you could get a good 'head and shoulders' shot with little or no distortion without having to stand in the models comfort zone.

Some years ago I moved over to digital using an Olympus E1 with a series of lenses which I still use.  However, most my photography is now wild life so the focal lenths are way past 50mm.

 

I Poser the only time I play with the focal length is wide scenes where I need to get everything in.  Without Depth of Field on the cameras are hardly real world anyway.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.