Reply To: Canon Users.

[cameraclicker]

I have a Rebel T2i!  The camera in my avatar image is a 5D Mk III, it was taken with the Rebel.  I got the Rebel to travel with, a lighter alternative to my bigger bodies.  It has been a wonderful body and has about 35,000 frames on the shutter.

The 1.6 multiplier is useful for figuring out angle of view if you are familiar with 35 mm film but not as helpful when speaking about other aspects of photography.  A 35 mm lens is always a 35 mm lens.  You can put a 10 mm lens on a 30D or 40D, and see the same view as 16 mm on a 5D Mk II.  At 100% view, it will be obvious the 30D or 40D image did not employ a 16 mm lens.   More thoughts about crop factor, and some images are here.

If you have a 40D, Rebel T2i and 5D Mk II, you can do the same tests I show.  A tripod and Photoshop are helpful.  Pick a scene, set up your tripod and mount your 35 mm lens on the 40D.  Pick something in the scene to centre the image on, then take the photo from the tripod.  Move the lens to the Rebel, mount it on the tripod and centre the frame on the same point, take the photo.  Repeat with the 5D.  Combine three images each at 100% using the 5D image as the base layer and the crop images as reduced opacity layers so you can still see the base layer.  I believe that will lead to enlightenment about sensor size and pixel density if you compare images with the spec sheets for the sensors.

Another page in the same area discusses depth of field.  The effect is easier to see with a longer lens.  A 100 mm lens for instance has a specific depth of field when focused at 10 feet, at f/8.  That depth of field is the same regardless of having a full frame or crop sensor body attached to the lens.  However, since you can fit more into the full frame viewfinder, you may move closer, and if you move closer, depth of field will decrease as you re-focus the lens.

A 35 mm lens is always a 35 mm lens.  A 100 mm lens is always a 100 mm lens.  Crop sensors really crop.  You can get digital magnification by cramming more pixels onto the sensor surface but bigger pixels do a better job of gathering light and result in a better looking image.