SharpCap Forums

Hi Robin,

My friend Chris and I were both imaging the other day and his sky brightness measured with the brain was .77e- and his SQM was about 18.7. Where my sky brightness with brain was around 2.4 and my SQM was around 19.1. I would have thought the sky brightness would track the SQM. Could you explain why his sky brightness was way lower than mine. He was using a ASI1600MC and I was using an ASI294Pro.

Don

Hi Don,

the pixel size and the f-ratio of your scope come into play to calculate the electron rate from the sky brightness. Higher f-ratio will give you a lower rate (inversely proportional to the square of the f-ratio). Higher pixel size will give you a higher rate (proportional to the pixel area).

cheers,

Robin

Thanks Robin. His F ratio was higher and my pixel size was larger.