12-29-2012 05:06 PM
About any lens can be a good portrait lens. It does come down to preference and what effect if any you are trying to accomplish.
As a general rule 85 - 135mm is an ideal focal length for FF bodies. That equates to about 50 - 85mm on crop bodies (Rebels, 60D, 7D).
Larger aperture lens can produce shallower DOF and of course they cost more. Longer focal length lens compress space and also have shallower DOF. Wider lens have more DOF and can distort facial features when used at close distances
For crop bodies I would go with a 50 f/1.4 or the 85 f/1.8. For FF bodies, I would go with the 85 f/1.8, 85L,100L or 135 f/2. If you are doing group shots, a wider lens would work better unless you have lots of space between you and the subjects. 24 to 35 for crop, 35 - 50 for FF as an example.
The 70-200 f/2.8 also makes a wonderful portrait lens. Just be prepared for some extra weight.
12-29-2012 08:26 PM - edited 12-30-2012 02:15 AM
For a crop body like 60D, I strongly prefer the shorter end (50mm) of that 50mm - 85mm "ideal" portrait range FOR CROP BODIES. I find that even with a 50mm lens I am having to back up sometimes. If you are indoors, that can be impossible. an 85mm prime lens is just too awkward indoors on a crop body, in my opinion. Kind of like trying to carry a 10' piece of lumber around in your house.
If you are outside or in a proper studio with some room, the 85mm end is great.
The thing is, I don't like to set up the backdrop and lightstands and stuff to get a shot of my kids. I like the less formal style, and shooting them where they are. Heck, they don't like the formal process either. The biggest issue in portraits other than lighting is proper background. A bunch of distracting clearly-identifiable people/objects/junk behind someone is the easiest way to separate mere snapshots from good informal portraits.
You can make almost any distant to semi-distant background into a nice blurry background if you use a normal to telephoto lens, at least 50mm to 85mm on a crop. A bunch of green stuff like trees, or a meadow, or anything. Even longer is better if you have lots of room. Even a sea of faces can be blurred nicely so that your subject's face pops if you are close to the subject and have a wide aperture.
1.) Get pretty close to your subject; the closer the better as long as your lens is 50mm or longer on a crop body (wider will distort the noses!), and
2.) Use an un-busy background, or at least don't have a pole or a person sprouting from subject's head, and
3.) Make sure the background is farther away (the farther the better) behind the subject than the distance you are in front of the subject, and
4.) Use the widest aperture (lowest f/number) you can; f/2.8 or wider (lower f/number) is ideal, or if the background is very far back you can make it work with f/4 or even narrower.
It blurs the background and makes your subject pop out of the shot nicely. This is much easier to do if you are using the 50mm on a crop than the 85mm. With the 85mm on a crop, you need to stand farther back from the subject, and that also means the background needs to be farther away too.
I have gotten nice shots of my little girls at busy trashy carnivals, and they look great because the background is just a blurry, dreamy cloud.