Nikon 50MM Lens for 35MM cameras
50mm is the standard lens for all 35mm cameras
When I say standard, the 50mm lens sees closer to what the human eye sees with a 35mm camera

Therefore on a 35mm, the 50 is standard, anything under say a 28mm is wide angle, and anything over 50 becomes telephoto say a 300mm.

Wide angle is useful in taking shots of buildings or where room is limited where you can't put distance between you and the subject say inside a building where space is limited.
The wide angle will actualy take a much sharper photograph than the standard 50 but is not always like the human eye would see it.
The Telephoto brings the subject from far away to closeup, like when photographing wildlife, if the Bear isn't close then you can zoom in on him to get the photograph.
Also with the telephoto, you can keep your distance and often the animals won't know
your there and more natural shots can be made.
On a different format camera called the two and a quarter by two and a quarter
2.25x2.25 format, the standard lens is a 90mm to see what the human eye sees.
The 2.25x2.25 has a film size of 2.25 inches x 2.25 inches which gives it superior
quality because the film exposed is so much larger and when enlarged the grain is smaller on the same speed of film as the 35mm
2.25 x 2.25 cameras are the norm of Professionals and are quite expensive, there are several manufacutrers of these larger format cameras such as Rollieflex, Hasselblad, Mamiya, Bronica and Pentax.
The two most popular are Hasselblad and Mamiya
You can expect to pay from $1,500 up for only the body of a medium format camera.
Most medium format 2.25 and 35mm cameras are sold body only, lenses are extra!

There are even larger format cameras, one I own, called a 4 x 5 which produces a negative which measures 4 inches x 5 inches in size there again increasing the size of the negative and producing great blow ups because a 4 x 5 is only doubled once to produce an 8 x 10 photograph.
There are even 8 x 10 cameras so the negative can be made as a contact print with no enlarging to produce an 8 x 10 photograph. These cameras are expensive if bought new, but Ebay has great deals because so few use these cameras anymore.
If you wished to do portrait photography, medium and large format cameras are an excellent choice!