Canon EF 100 f/2 USM

[Kilvik]

I am not sure if this is the right thread. I currently own a Canon 7D. I have been learning the camera while using the Canon ef-s 18-55mm f 3.5-5.6 is. As much as I've enjoyed the camera I haven't been pleased with the lens.
We're having our first kid and I have been working on portrait photography. I have been researching portrait lenses and I keep coming across the Canon EF 100 f/2.0 USM. And its in my price range.
I would like to know two things. How the lens compare to each other and is the one thats being recc a good match for the 7D or should I consider another one.

[inkista]

It's a very different kind of lens, and a good one. But the issue is whether it'll be "too long" and frame too tightly for you on a crop body or not. In smaller spaces, or for wider framing, it can be a bit too long, depending on the size of the room you're working in (how far can you back up?), what kind of working distance you like, and what kind of framing you prefer.

The reason the 100/2 ends up in fewer bags is that most folks often get a 100/2.8 Macro USM, and use it to do double-duty as a macro and a portrait lens. You'll find more reviews on its identical cousin, the EF 85mm f/1.8 USM for this reason. But the behavior is pretty similar.

It will be longer, sharper, and faster to autofocus than your 18-55, but it won't be stabilized. Realize that that means the 1/focal_length rule comes into play: generally speaking if you have good handholding technique, the rule of thumb is to use a shutter speed at or above 1/100s for a 100mm lens to mitigate camera shake blur. Some folks would halve that (1/200s) or throw in the crop factor (1/160s). It's a matter of personal skill level and need for sharpness. So, the longer the prime you choose, the more restricted you'll be in terms of available light shooting, unless you use a flash or a tripod.

[gturner]

on a 1.6 crop camera like the 7D, the lens is pretty long and will very hard to use indoors for anything more than head shots.

A 50mm 1.4 would be far more useful on that body for everything from headshots to full body.