Canon EOS 40D - Wikipedia
Canon EOS 40D body review
Hannu's blog: Canon 40D Challenge
Canon EOS 40D vs. Canon EOS Rebel T5i - Camera Comparison
Canon EOS 40D Review
Canon Digital SLR Camera Body [EOS 80D] with 24.2 Megapixel (APS-C) CMOS Sensor and Dual Pixel CMOS AF - Black : Electronics
Solved: EOS Rebel T1i & EOS 5DS Lens Compatibility - Canon Community
Canon Crop Factor
Canon EOS 40D Review
Canon APS-C Camera Models
Field of View Crop Factor - MattWiki