Question RE: Lens choice for portrait photography

[kptasteve]

What advantage is it to use a Canon EF 70-200 F/2.8 L lens versus a Canon lens like say 70-105 zoom US for taking portraits. I see the longer lens being used alot and wonder why?? Any personal stories or tips as to why one is used over the other and when??


Steve

[LeeR]

In the days of 35mm film the standard 50mm lens that came with the camera required that you be close enough to smell a models toothpaste in order to get a good headshot. For that reason, most pros preferred a 105mm lens since you would not have to invade someone's personal space to make a good portrait. Depending on the camera you have today, that would translate to an 50mm, 85mm or 105mm depending on the size of your sensor.

I would think the 70-105mm zoom was, therefore, an ideal lens for portrait work. I, personally, never liked having to stand in the next county for a headshot, but there may be some who like the shorter DOF, the higher aperture and the flattening effect of the longer lens. There's just no accounting for taste.

[Benji]

When I switched from my medium format camera to a DSLR I wanted to replace my three MF lenses (40mm, 80mm and 150mm lens) with one zoom. The 28-105 fit the bill perfectly for portraiture.

A wider lens would be nice for some of my commercial work, but so far I've been able to wing it.

Benji

[leftquark]

Longer focal lengths do a couple things, but most importantly:
1) The longer the focal length the more blur in the background at larger apertures (small f/numbers). Since you most likely want the model in focus and the background out of focus the longer focal lengths will help

2) Longer focal lengths will also compress the distance between objects due to the perspective from the more distant location. What this means is that it can kinda "squish" (not abnormally though) the model so that they may look a tad skinnier.

To expand on #2 I did a quick search on google and found this page:
If you use a normal or wide angle lens for a tight head shot, you will be so close that the nose will deform outward and the ears will recede in the image, giving a strange out of balance look to all the features. The ideal starting choice is a lens of at least twice the "normal" focal length for your format, for head shots. That way, when you fill the frame with the face, you are farther away and the relative distance of nose to ears is much less of the total distance, compressing them back into what is a normal appearance.