[Shiraz (Ray)]

Originally Posted by RickS

Interesting experiment. Thanks for that, Ray!

Cheers,
Rick.

thanks Rick - obviously cloudy down this way. have also been messing around with star shapes, trying to find a way to get around the halo problem from your post - interesting problem in PI.

Originally Posted by MrB

Nice work Ray.
Don't forget there are two green for each blue and red in a Bayer matrix.
I couldn't find a colour data sheet for the MT9M001, but another Aptina MT9 sensor data sheet shows a QE of ~38% for red, ~43% for blue and ~50% for green.

Oops, I didn't see you had addressed this in your OP, I may have missed your update.

Thanks Simon - yep, added that as an update/

Originally Posted by Dennis

Good work and analysis Ray, thanks for this interesting and useful experiment.

Science at home eh, who needs a certified laboratory and calibrated equipment! Top stuff.

Cheers

Denis

Thanks Dennis. Nowhere near a controlled experiment, but probably worth doing.

Originally Posted by nebulosity.

Cool experiment Ray, I reckon you would be pretty correct, about the same as what I roughly measured with my colour and mono 350D sensors.

Jo

Thanks for the confirmation Jo - where did you get a mono 350D from?

Originally Posted by Astro_Bot

Thanks for that comparison, Ray. Very handy.

Thanks - was interesting to do

Originally Posted by bert

I think you may overstating the sensitivity of the mono chip.

You didn't take into account light loss when shooting through colour filters (rgb) as opposed to the constant loss via the Bayer matrix on the colour filters.

There would be a few ways to test this.

Brett

Thanks Brett. Agree, this was just a test of the relative sensitivities in detecting photons from a bright broadband source - ie, obtaining luminance (and colour in the case of the OSC). Colour data will require extra exposure for the mono system, but mono allows binning to be used, so it is difficult to compare directly with Bayer. It is probably reasonable to say that a cooled Bayer system will require something like 1.5x as long to produce a similar overall SNR result as a cooled mono system with filters etc. And then there is the resolution reduction inherent in a Bayer matrix, but that is a different issue.

One often sees very high quantum efficiencies quoted for Bayer cameras and I wanted to confirm that these do not translate into broadband sensitivity. However, it was interesting to find that OSCs are actually a bit better than might be expected from a cursory understanding of how they work - must get my QHY8 back under the stars.

Regards Ray