Canon released an updated SLR digital camera, called 20Da. The "a" suffix is short for astronomy. This camera is identical to the 20D, except for:
* Infra-red filter replaced -- allows infrared photography of deep space. Imaging Resource notes this causes a red tint in normal photographs.
* Transmissive mirror -- allows you to see through the LCD at all times.
There is an extensive monologue over the impact of these two features at Canon Japan announces EOS 20Da.