British Astronomical Association, Variable Star Section (BAA-VSS)
Sat, 03/02/2024 - 14:21

I read somewhere that there is a problem with CMOS camera photometry at exposures less than about a second.

I wanted to check if this is true and why please.


American Association of Variable Star Observers (AAVSO)
I think this question could…

I think this question could use a bit more context to give a good answer, like why you would even consider sub-second exposure times in the first place.

I would see two reasons why you might want to do so:

1) a you really need that time resolution, that is you actually want to create a time series with one or more measurements per second (wow!).

2) your are trying to measure a really bright source and stopping down the aperture is not an option and using a neutral density filter isn't an option either. 

In both cases, I guess the biggest problem is the atmosphere (not the sensor) which will make your target flicker in ways that will degrade the photometry considerably.

In all other scenarios, where you don't need a second-like cadence or risk saturation, you could just as well take longer exposures instead of combining seb-second exposures, which would be preferrable because you get less noise from the read-out of the sensor (not just with CMOS but any other sensor as well).

So I'm not quite sure what would be the application for this kind of high-speed photometry, at least not for amateurs.

Can you give some context perhaps? Maybe I'm missing something here.