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First Light with ASI290MC

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#51 gdd

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Posted 21 March 2017 - 04:27 PM

Sometimes the references to read noise in the product descriptions are confusing. Some products refer to the read noise at a high gain setting and others to the read nose at a low gain setting. If you don't look at the graphs you might make the wrong choice. If I am interpreting the significance of the graphs correctly you want the product with the lower read noise at a high gain setting if image under dark skies; you want the product with the lower read noise at a low gain setting if you image under light polluted skies. I'm assuming you will need to use the low gain under light polluted skies to increase your exposure time to collect enough signal.

 

Gale



#52 John Boudreau

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Posted 22 March 2017 - 08:56 AM

I also read that a mono camera negates the atmospheric dispersion and does not make the images ungainly after capture. So the Mono would be best for planetary imaging for a B&W image. However, you could also throw in LRGB filters too.

Monochrome cameras do not negate atmospheric dispersion unless you are using a narrowband filter. For typical RGB tri-filter color imaging with a mono cam, there is still dispersion within the bandpass of each color filter that can only be corrected with an ADC. Technically, there is still dispersion with a narrowband filter, but it is so minor to be of no real consequence. Of course all this is only an issue if the target isn't very high in the sky, as dispersion becomes less of an issue with increased altitude.

 

You may have read that color cameras appear to be more effected by dispersion than a mono cam--- this is due to the fact that the bandpass profiles of Bayer filters on a color cam have a good deal of overlap, usually much greater than the sharp-sloped overlap between a typical RGB color filter set used with mono cams. An exception is the Astronomik RGB set, that has bandpass profiles similar to a typical OSC Bayer matrix.




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