I think the two lenses I use most at the moment are perfect for portraits with the Canon digital cameras. On my EOS-5, I always used my
85mm f1.8, which is considered a superb portrait lens even though it's not an "L" lens. It was designed to have a very pleasing "
bokah" (warning, brain-melt matierial). On the digital cameras, it has the equivalant of 135mm. At 85mm, I could have troubles getting a real tight shot because the lens wouldn't let me get close enough to focus. It was usually fine for adults, but a tight shot of a baby had to happen with a crop afterwards. At 135mm, that problem is solved, and it is now on the longer end of the portraiture range.
I never expected to use it as much as did when I bought it. I fell so in love with it that my three zooms stayed in the bag all the time, and then I sold two of them.
The other great lens, if you have the money, is the
50mm f1.4. This lens becomes an 80mm on the digital cameras, almost up to what the 85mm was, so it fills in the gap for the 85 after conversion. The bokeh on this lens is also beautiful.
If you are on a budget, the
50mm f1.8 is a good alternative for the digital cameras at a very reasonable price. It will allow you to get in for a head-and-shoulders shot, and it has a wide aperture for limiting DOF.
Here's a comparison between the two 50mm lenses.
