The Canon EOS-20Da is identical to the EOS 20D except for a modification to the low-pass filter, which now filters less infrared (IR). This camera is best suited to astrophotography as well as infrared photography. It would be possible to use it as a normal camera but would require an external IR cut filter. In addition the camera has a partially transmissive mirror, which enables live focusing on the LCD monitor (this can only be done for short times and requires the mirror to be locked up). Pricing has not yet been announced.
The low-pass filter positioned in front of the EOS 20Da?s 8.2 Megapixel CMOS sensor has been modified to yield sharper and higher contrast images of various astronomical phenomena such as diffuse reddish nebulae. The modification increases the transmission of light at the wavelength of 656nm, known as the Hydrogen Alpha line, or Hα wavelength, by a factor of 2.5x compared to the standard EOS 20D digital SLR.
While traditional digital SLRs lack a live preview on the LCD monitor due to the reflex mirror and shutter, the EOS 20Da digital SLR resolves this issue by locking up the mirror and opening the shutter to display a magnified live view of the subject on the 1.8? LCD monitor. (This feature is effective for night viewing conditions only. It cannot be used in bright light.) To ensure a sharp focus, the central portion of the image can be magnified on the LCD by 5x (4% of the picture area) or 10x (1% of the picture area). The live view mode can also be viewed through a TV monitor while connected to the EOS 20Da camera?s video OUT terminal.
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