sigh.. sometimes my fren woon is a bit slow to understand things...
This link,
http://forums.dpreview.com/forums/read.asp?forum=1019&message=27645546 best answers what Portrait Lens are..
When I refer or most ppl refer to portrait lens, it refers to a set of lens that are best.. eg the classics like 35, 50 and 85... some even can use 24-105 or the even the 50 macro or 100 macro... would you use to shoot a portraitur with a 70-200 or 300 or 500... especially indoors with limited space?? No you would use the 50 or 85 or even 35..... and if you have the space like outdoors are you seriously gonna use a 70 -200 or if you got the budget a 500 mm to shoot a portraiture??
Why the pros like to class lens into certain terms like sports and landscape and even portraiture is because certain lens only can to a certain job... no pro is going to call a 50mm a wildlife lens and take one out to got shoot lions... YES i agree that the 85 is not called a Portrait lens... ITS a PRIME lens.... BUT it is classed in a group that some call a portrait lens.. just like some would class 70-200 f 2.8 not sports lens, they would class 500 f4 into wildlife lens....
so elevenith what are the lens classified under Landscape lens?? in the canon website or nikon website are they classified as landscape lens? or as wide-angle or what?? someone had decided to coin the term Landscape Lens and advised what lens were suitable.. so the same thing with Portrait Lens...
So remember, just becoz one is now doing a part time degree at some uni and studying one module of photography in 6 months doesnt make you suddenly the resident expert in photography.... hahaha