Round 1: Canon 100-400mm @ 100mm vs. Canon 100mm 2.0

Canon 450D at ISO 200, two lenses were tested again each others namely:

1. Canon 100-400mm f4.5-5.6L USM
2. Canon 100mm f2.0 USM

So here are the testing shots at f/4.5:-

Prime at f/4.5 resized:-


Zoom at f/4.5 resized:-


Prime at f/4.5 center cropped:-


Prime at f/4.5 border cropped:-


Zoom at f/4.5 center cropped:-


Zoom at f/4.5 border cropped:-


And then the test shots at f/8:-

Zoom at f/8 resized:-


Prime at f/8 resized:-


Zoom at f/8, center cropped:-


Zoom at f/8, border cropped:-


Prime at f/8, center cropped:-


Prime at f/8, border cropped:-


Finally, prime at f/2:-

Center cropped:-


Border cropped:-


Resized:-


The 100mm f2.0 is recommended for astrophotography in a number of website, I guess that I have to stop it down to f2.5 or slower and considering the price and versatility, it's unbeatable.