Portrait lens

almost like a Petzval lens: the Ross Portrait Lens

Nowadays portrait lens means a kind of lens that's fine for face likenesses. Lenses for 35mm film cameras with focal length between 80mm to 135mm might be fine portrait makers since some distance is needed to get a face into the image frame. Lenses with smaller focal length would distort the images by giving "big nose" portraits because of short subject distance. The first portrait lens was the fast Petzval lens, invented in 1841 by Jozef Maximilián Petzval. At that time the lense's speed made it a portrait lens because the average contemporary lenses needed exposure times measured in minutes whilst the Petzval lens reduced enlightment time to 30 seconds. The modern portrait lenses are still fast lenses because modern portraiture mainly means sharp image of the subject before unsharp background. A nice bokeh might be an additional criteria to select a lens for portraiture.

35mm cameras with portrait lenses:

Helios-40 85mm f1.5	Zuiko 100mm f2.0	Pro-Tessar 115mm f4.0
image by siimvahur	image by Siippou	image by jr55