Canon EOS 20D Astrophotography vs Canon EOS 40D

This is a full comparison between the cameras Canon EOS 20D Astrophotography and Canon EOS 40D. We compare them by looking at the categories you see below.

Canon EOS 20D Astrophotography

Canon EOS 40D

Manufacturing

These cameras are both manufactured by Canon.

Canon EOS 20D Astrophotography were released 2005 and Canon EOS 40D was released 2007. That is a 2 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera	Released
Canon EOS 20D Astrophotography	2005
Canon EOS 40D	2007

Type of camera

Both these cameras are DSLR cameras. No difference there.

Sensors / crop factor

Both these cameras have the same sorts of sensor (called "Canon APS-C") which means that if you compare these cameras side by side the lenses will also have the same experienced focal length. Neither of the cameras has a Full frame sensor which means that you will get a "crop factor" where the camera's sensor size affect the focal length with a multiplier.

Camera	Focal length, 50mm f/1.8 **
Canon EOS 20D Astrophotography	80 mm Canon APS-C sensor Crop factor/focal length multiplier by * 1.6
Canon EOS 40D	80 mm Canon APS-C sensor Crop factor/focal length multiplier by * 1.6

** Experienced focal length when using a lens such as a common "50mm f/1.8"

Learn more about crop factor and focal length multiplier here:
Camera selection can affect the focal length (Canon)

Resolution

Canon EOS 20D Astrophotography has a 8,2 MP (Megapixels) resolution while Canon EOS 40D has 10,1 MP. If we break down this in more detail this is the data behind the numbers:

Camera	Megapixels
Canon EOS 20D Astrophotography	8,2 MP 8185344 pixels 3504 x 2336
Canon EOS 40D	10,1 MP 10077696 pixels 3888 x 2592

Canon EOS 40D has a 23 % larger resolution than Canon EOS 20D Astrophotography. This could give you more details in the picture but also a possibility to crop more in the pictures, afterward while editing the pictures, if needed that is.

ISO range

Both of these cameras offer the exact same ISO range. They both have 100 to 3200.

Camera	ISO Range
Canon EOS 20D Astrophotography	100-3200
Canon EOS 40D	100-3200

Autofocus and lens compatibility

Both of these cameras have a built-in autofocus motor. Some lenses, that support autofocus, do not have an autofocus motor of their own but this won't cause any problems with these two cameras.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Canon EOS 20D Astrophotography
Lens compatibility chart for Canon EOS 40D

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Canon EOS 20D Astrophotography can shoot up to 5 pictures per seconds and Canon EOS 40D can shoot up to 6,5 pictures per seconds.

Camera	FPS (Frames per second)
Canon EOS 20D Astrophotography	5
Canon EOS 40D	6,5

Ability to record movies

It is becoming more and more popular to record movies with digital cameras.

Though, neither Canon EOS 20D Astrophotography or Canon EOS 40D can shoot movies so if that is a functionality that you are really looking for you should look elsewhere.

Weight

The weight of the camera can be an extremely important factor, especially if the camera is about to be used, or carried around, for several hours at a time.

Canon EOS 40D weighs 822 gr (equal to 1.81 lb) which is 7% heavier than Canon EOS 20D Astrophotography and its 770 gr (or 1.7 lb).

Camera	Weight
Canon EOS 20D Astrophotography	770 gr 1.7 lb
Canon EOS 40D	822 gr 1.81 lb