Thu, 03/25/2021 - 22:01
I currently use a CMOS color camera for photometry. I either analyze full-spectrum images (400-700nm), or Red, Green, or Blue Bayer-derived image data. My understanding is, when I submit an observing report, I should use:
- CV or CR for the full-spectrum data dependent on the comp star magnitude/color
- Or TR, TG, TB for Red, Green, or Blue images, respectively.
Is this correct?
Should I describe my camera as CCD or DSLR, since there is not a CMOS choice?
Hi Gary,
Reporting an observation as CV or CR implies that there is no filter (Clear). Problem with a color CMOS is that filters are built into the bayer array; you can't get rid of them. But if you binned 2x2 so each pixel had the benefit of the 3 colors, then I would think that could legitimately be considered Clear or full-spectrum as you describe it above. So CV or CR would be good.
If you debayer the images so that you have 3, then TB using B references, TG using V references and TR using R references it correct.
What to call a CMOS observation? I would generalize the current categories like so:
CCD: means electronic, monchrome imager using photometric filters
DSLR: means electronic, color imager with bayered filters applied to the sensor.
So your color CMOS data should be classed as DSLR.
Cheers,
George
Thanks for your feedback, George.
I'm not sure that…
George,
I'm not sure that would be accurate. There are some differences between OSC Astro cameras and DSLR.
Cooled is the most obvious, and low Ev noise with specific firmware to support astro imaging modes.
Of more impact to VSO is the differences in the filters in front of the sensor which are typically clear or a cut IR/filter.
Unlike DSLRs, most astronomy OSC CMOS cameras automatically generate FITS images with the FITS header that captures the information from the camera and often the positional information provided by the telescope mount.
The well depth, processing speed, image/sensor size continues to advance significantly. ZWO currently has a medium format Astro OSC that is being tested with a FITS image file size that will be somewhere between 150 - 200mb.
What is strongly needed is a clear, concise instruction set of how to process OSC data into what is needed for VSO data. The why/technical /theoretical details needs to be separated to the addendum for those that want to know. The current DLSR "manual" is 110 pages long and is full of technical explanations which make it a great technical reference manual. But as a How To manual for new members it leaves much to be desired (IMO), but I don't think it was written with that end in mind.
IMO. YMMV
Your comments are timely and well received.
The issues of OSC cameras and how to handle their images and how are they related to DSLR cameras is a hot topic. The Instrumentation and Equipment forum ( https://www.aavso.org/forum/8235 ) is grappling with this. And there will be lots discussion at the meeting next week!
The interest in the DSLR and OSC is that it is a low cost entrance to the VSO game. We need to prepare the manual and instructions to make these a inviting starting point for new observers.
George