I have been looking at old brass lenses lately . . .the ones that used to go for <$20 at the camera shows in the ‘80s and’90s. Now I am interested and have a few questions.

What is the difference between a “landscape” lens and a “portrate”l ens?

Can a Petzval lens be either or both?

Is there a difference between a camera lens and a magic lantern lens in this era of photography (1860-1890)?

Who made the "good" ones?