Canon's astrophotography DSLR — the EOS 20Da, H-alpha-modified 8MP APS-C, EF mount, 2005.
The Canon EOS 20Da, released in 2005, was a specialised astrophotography variant of the enthusiast EOS 20D digital SLR. It was produced in limited numbers for astronomers and remains a niche body sought by those imaging the night sky rather than a general-purpose camera.
This is an APS-C digital SLR based on the EOS 20D, differing in a modified infrared-cut filter that passes more of the deep-red hydrogen-alpha wavelength important for photographing emission nebulae. It carries an 8-megapixel APS-C sensor, takes Canon EF-mount lenses, and uses an optical pentaprism viewfinder. It also added a live-view mode for focusing on stars, unusual for a DSLR of this date. It is a stills-only body with no video.
The 20Da is an astrophotography tool: its filter modification records red nebulosity that a standard camera suppresses, making it suited to deep-sky imaging through telescopes and lenses. This same modification skews daytime colour balance toward red, so it is a specialist body rather than a general reportage or portrait camera. Handling is that of a mid-2000s enthusiast DSLR.
As a rare astrophotography variant, verify the modified filter is intact and the body has not been reverted. Request the shutter actuation count against the enthusiast-class rated life, inspect the sensor for dust and marks, and test the rear screen for dead or stuck pixels. Check the card and battery door latches, and confirm the BP-511 style battery holds charge with a working charger, as this generation of cells is ageing.