Sensor analysis GPCam3 178C

Discussion of features and issues relating to Altair Astro Cameras
Post Reply
Shakyhands
Posts: 2
Joined: Mon May 11, 2020 1:48 pm

Sensor analysis GPCam3 178C

Post by Shakyhands » Mon May 11, 2020 1:55 pm

Just tried the sensor analysis tool on my GPCam3 178C. Managed eventually to get constant illumination of the correct level, got nice linearity results for the sensor, but was surprised that the full well capacity was only about 10600 e rather than the 15000 e quoted by Altair. I’m new to this, is this kind of discrepancy normal or should I contact Altair? Seems to me that my dynamic range is down by about 1/3 on the specification.

Thanks in advance
Neil

User avatar
admin
Site Admin
Posts: 5172
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Sensor analysis GPCam3 178C

Post by admin » Mon May 11, 2020 4:36 pm

Hi Neil,

It looks like you're not alone – I have just checked the analysis files for that camera and related models that I have here and they all seem to have lower full well depth numbers - about 11,000 to 12,000 typically. The same seems to apply to the qhy variant of the camera, but not the ZWO one.

Not quite sure what to make of this – perhaps the camera is running with a small amount of gain when the gain seems to be set to minimum for some reason.

Cheers, Robin

Shakyhands
Posts: 2
Joined: Mon May 11, 2020 1:48 pm

Re: Sensor analysis GPCam3 178C

Post by Shakyhands » Mon May 11, 2020 7:40 pm

Thanks Robin, good to know I’ve not made a mistake with the measurement. I’ve had the camera for a few years so it’s a little late for me to complain to Altair. Lockdown has given me the impetus to resurrect my telescope.

I’m enjoying learning SharpCap and AP in general; I come from a career in laser spectroscopy, so I’m used to using CCD’s and optimising S/N, but imaging is new to me. I’ve found the material you’ve made available on optimising gain and exposure length invaluable, I couldn’t understand from my own experience why people assumed that monotonically increasing sub length was always beneficial, it was good to read your documents and see the YouTube videos confirming that this is not the case.

Thanks again,
Neil

User avatar
admin
Site Admin
Posts: 5172
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Sensor analysis GPCam3 178C

Post by admin » Tue May 12, 2020 5:53 pm

Hi Neil,

Glad to hear that you are getting some use out of your camera – I think a lot of people have been coming back to astronomy in the last couple of months as they have more time at home. My goal with the sensor analysis and smart histogram functions in SharpCap and the talk I gave at the PAS was to try and fight a bit against the 'longer subs are better' dogma that had become rather ingrained in the astronomical community. It's always good to hear that the message is getting through to people :-)



Cheers, Robin

Post Reply