Is this amount of noise expected, or am I doing it wrong?

The picture below is a crop (at 1:1 scale) of a photo I just took. It was taken with a Canon 7D and the 24-105mm F4 lens (RAW, F4, ISO 2500, 1/160s).

It looks properly exposed to me, so where is all this noise coming from? What I am trying to figure out is:

1. Is this an acceptable amount of noise?


2. Do photographers just correct this in post, or could I have done something else in camera?


3. Would it even matter if it was printed at something around 16X20?

Answer

This is normal considering the high ISO you are using on that camera. If you look at samples for each ISO with the Canon 7D, yours show more noise than the ISO 1600, similar to the ISO 3200 crop.

Notice that I only shot full-stop ISO which is important with Canon DSLRs because the gain to obtain the 1/3 stops in between is applied in software by the processor which amplifies noise more than the on-sensor gain which is used to get the full stops.