Canon EOS 20Da
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| Canon EOS 20Da image by joka2000 on Flickr (Image rights) |
The EOS 20Da was offered by Canon beginning in 2005, as a variant of their standard 8-megapixel 20D but optimized for astronomical photography.
Conventional DSLRs include an infrared blocking filter. But many gaseous nebulae emit light at the hydrogen-alpha wavelength of 656.3 nanometers, which conventional IR filters would attenuate significantly. The 20Da's filter was claimed to pass more than 2.5 times as much light at this wavelength, without noticeably compromising daytime color balance. The camera also offered a 5x or 10x magnified live view, to aid with focusing on dim astronomical objects. Finally, Canon made modifications to reduce noise during long exposures; a review in Sky & Telescope magazine found a 20-30% improvement in noise levels.[1]
These improvements came at a price premium of approximately USD $700 relative to the stock 20D.
References
- ↑ "Canon's Astrocamera: The EOS 20Da" Sky & Telescope (US) Volume 110, No. 5, November 2005, pg. 84
