How old is an elderly man?

nah

but a 50 to 99 year old woman is a thing to behold

I wouldn't say a person this age would be considered elderly unless he looked the part. Many people very active, hale and healthy, well into their seventies or beyond, people who hold their age well.
I think it's a matter of perception although, in north america, you are legally considered a senior citizen at the age of 65.

Thank you both

It's all relative. To a 8 year old. A 38 year old is decrepit, senile, and completely out of touch with the real world.