SharpCap Forums

When using the brain function to measure sky brightness could it be thrown off by thermal noise or amp glow. Would it be advisable to use a dark frame during this procedure?

Anyone have an answer for this, I'll be setting up in a few hours.

Sorry I don't have an answer to this but I'm very curious to see what Robin has to say on the subject. Some of the cameras I use have very pronounced amp glow that must be showing up in the calculation of the sky brightness measurements the brain does. I'm sure we'll get an answer soon.

-Wikkett

I'm suspecting a well matched dark certainly won't do any harm.

Hi,

I think the best option would be to select a sub region of the image away from the stronger amp glow regions for the sky brightness measurements.

Using a dark frame won't work for the sky brightness background measurement as the measurement procedure changes the exposure constantly to find a level that gives it a strong enough signal to work from – you wouldn't know in advance what length of dark frame to use. Additionally, using a dark frame would mean that any thermal noise would be removed from the image being assessed which would actually be a negative in this circumstance as we are trying to deal with how the sensor responds to the signal it sees without dark subtraction in our noise calculations.

Cheers, Robin

Actually having just thought about this, I suppose I really ought to have the measurement procedure turn off dark and flat correction while measuring (if it doesn't already) as both could impact on the final measurement, although I expect that the size of the impact is not going to be too significant.

Cheers, Robin

Thanks Robin I'll bear it in mind.