Atik 460EX v Atik 490EX
Monday, 24 June 2013 | Steve
A. For low noise noise and high sensitivity, the Atik 460EX wins. But only by a small margin because both sensors are from the same family so have similar characteristics. Also, the 460EX with it's larger pixels has greater dynamic range (larger pixels hold more electrons). The difference is in the region of 25-50%. This means you can achieve 25-50% longer exposures without burning out the highlights.
For resolution the 490EX wins. If you are imaging with a short focal length telescope, like a Mini-Borg or camera lens, the 490EX's higher resolution is an advantage. The higher resolution is also an advantage with the colour (OSC) version. This is because for the Bayer colour matrix to work (determine the correct colour) a star needs to cover at least four pixels, more is better. The higher resolution 490EX places more pixels under a star compared to a 460EX so is more likely to determine accurate colour. Again, this advantage applies more to users of short focal length telescopes.
Generally, unless you are using a telescope with an unusually short focal length, we recommend the 460EX for it's lower noise, higher sensitivity and greater dynamic range.