Shel wrote:
> What is a "portrait lens?" Can someone define it for me? What
> are the characteristics of a good portrait lens?
I suppose by definition it's a lens you use to make portraits with. More
typically, it's a medium telephoto of 85mm to 105mm focal length, since
those are frequently preferred to make portraits with.
At the turn of the century a good portrait lens was a highly prized tool,
and various portrait photographers were highly possessive about their
carefully selected lenses. Even until recently, some of these lenses were
sought after and sold for far more than their more pedestrian brethren. They
have names few photographers recognize today.
A good portrait lens back then (of course, they were all view camera lenses)
was a lens that looked sharp without obvious softness, but that didn't
resolve too much. The reason for this is that the human eye and mind, when
"recognizing" a human face, typically is highly sensitive of identifiers in
shape, form, expression, and so forth--permanent features of the face being
recognized; but tends to ignore what we know to be transient, insignificant
surface details--blemishes, stubble, bad skin, lines, etc. We're aware that
these things are not identifiers, so the mind tends to give them less
emphasis in the recognition process.
Some feel that a good portrait lens should do the same. Too much resolution
of surface detail is a distraction from the way a person looks. Surely, all
of us have seen photographs of ourselves or our loved ones that "don't look
right" because of excessive resolution--every pore pronounced, every crease
and line emphasized. It's like a caricature.
Most of the early portrait masters used relatively simple lenses that had
decent contrast but not very good correction. Further control was afforded
through choice of apertures.
These days, what I would look for in a portrait lens is a lens that has high
contrast for large structures (say, 5 lp/mm), but not very good resolution
of small structures (30-40 lp/mm) and good soft blur or "bokeh."
I don't mind if a lens only has these properties at a certain restricted
range of apertures.
I have a number of old portraits in my collection that are absolutely
stunning--gorgeous, flattering yet clear. In my opinion the high point of
portrait photography passed many years ago.
--Mike
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