QHY5ii Camera and Slow 15s image refreshes
Chris Pendred
I recently received some some support from Bruce and the team on another thread, but I wanted to summarized one of the point I managed to get support for as I believe it may help others who have similar issues.
I had a lot of trouble trying to use my old QHY5ii camera working with PHD2. The images would only refresh every 15 seconds or so with a similar frequency for graph updates even though the exposure speed was set to 2 seconds. There were also a lot of hot and cold pixels showing.
The result I got was poor guiding graphs with + or - 4” fluctuations. About 70% or my light frames had short streaks instead of star points. So I had only 30% off images taken that were worth stacking.
To cut a long story here are the findings relating to getting the camera working.
With the QHY camera it has 10-bit internal data which is scaled to either 8-bit or 16-bit before the data is returned to PHD2. With 16 bit setting in the PHD2 profile the image refreshes were long but with 8 bits setting the images and graph refreshes at the correct 2 second rate.
I also compared using the native QHY drivers with the Ascom QHY Guider Driver. I found I could only get the 2 seconds refresh rate on the screen by using the Ascom Guider driver.
So in phd2 I made a fresh profile with the wizard based on 8 bits and the QHY guider driver.
In regards to saturation levels setting at 65335 also resulted in 15 second image refreshes. 255 bits resulted in a poor quality image. What worked was to switch the saturation detection in PHD2 to “via star profile”. This provided a much better quality image.
The images also had a lot of noise and loads of hot / cold pixels. It turned out Phd2 was guiding on hot pixels some of the time. I was advised to make a good set of darks in PHD2. I found that the more darks I took the cleaner the image reducing noise and resulting in fewer hot / cold pixels. I made darks libraries using maximum of 20 exposures and got much better quality images for guiding.
USB port selection - I ended up connecting the camera to a powered USB port to ensure it has sufficient power to operate.
I also made sure I was using a good quality USB cable.
Also I turned off power management of USB ports and hubs in windows device manager. This prevents windows turning off power to the camera.
In Device manager “Intel management engine interface #1” under “power management” I unticked “allow the computer to turn off device to save power.”
The above steps enabled me to at least get s good starting point to build on. Whilst not perfect, my guiding is a significant improvement on what it was previously.
Hopefully these points will help anytime else struggling with similar issues.
A big thanks to Bruce and team for their support.
Brian Valente
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