CMOS Camera for Photometry

[Mick Crook]

Hi Folks,

Is anyone here using a CMOS Camera for variable star photometry? In the past I have used  FLI and SBIG NABG CCD cameras, which were ideal for photometry, but sold them a few years ago. I now have a Canon DSLR and an Altair Astro Hypercam IMX174 CMOS Camera. I know DSLRs can be used for photometry, but what about my CMOS camera? I notice there are some limited discussions on the AAVSO forums regarding CMOS cameras and photometry and it looks like some observers are having success with them, but there isn’t much info there at the moment. I would like to do some photometry again later in the year, but I don’t want to spend money on another CCD if my existing CMOS can do the job.

Cheers,

Mick  

[James Screech]

I’ve been using a CMOS camera for a few years (ASI1600MM-C) without a problem. Most (if not all) DSLR cameras use CMOS sensors, so if they work a dedicated cooled astro CMOS camera is fine.

James

[Dr Andrew Smith]

NASA are using a CMOS camera on their Parker Solar Probe.

I and others use them for spectroscopy without any issues. As with CCD you need to check the linearity etc.

You also need to set the gain and offset to suit. You effectively can trade off read noise for dynamic range. 

Regards Andrew 

[Mick Crook]

Many thanks for your comments James and Andrew. I’ll check the linearity and see how it goes!I

Cheers,

Mick

[George Sallit]

A bit late but try looking at this page for some background, it looks good for CMOS cameras being used for photometry but watch out as they are only 12 bit which limits the dynamic range. http://www.astrosurf.com/buil/CMOSvsCCD/index.html

[Nick James]

The 12-bit quantization and corresponding well-depth isn’t really a problem since CMOS sensors have very low read noise so the normal way of using them is to externally co-add multiple short exposures. This has many advantages over a single long exposure.

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