Unexplained hot pixel clusters in live stack.
Posted: Mon Mar 30, 2020 3:02 pm
Hi,
When I have live view active with 240 sec exposure,with dark and flat to calibrate, there is no noise besides a few hands full of isolated hot pixels. I'm using the histogram stretch of the camera control panel. The stretch is extreme to make the hot pixels visible, the scope cover is on. So far, everything looks pretty good.
The same exposure stored and viewed via folder monitor camera, with same calibration frames and same stretch gives the same result. This is still consistent to me.
However, when I use this same stored exposure in live stack as single frame (via folder monitor), with the same dark and flat files, with the same extreme stretch in the camera control panel, I get significant larger and more hot pixel clusters, and a visible layer background noise. The stretch controls of the live stack histogram are left at default. I get similar result when I reset to camera control panel histogram controls,and use the live stack histogram controls. (slightly more noise though)
Doing live stack with same exposure settings and sensor temperature, I get similar result. Hot pixel clusters and visible background noise. Subsequent stacked frames reduce the background noise as expected. But the hot pixel clusters remain, some of them even grow. The hot pixel clusters are the reason I was looking into this.They show up in the stack and on a bad polar alignment day....
Is there an explanation for this? Is the live stack view at a larger bit depth? I don't mind about the very low level noise, but the hot pixel clusters are really annoying me.
Kind regards,
Rob.
When I have live view active with 240 sec exposure,with dark and flat to calibrate, there is no noise besides a few hands full of isolated hot pixels. I'm using the histogram stretch of the camera control panel. The stretch is extreme to make the hot pixels visible, the scope cover is on. So far, everything looks pretty good.
The same exposure stored and viewed via folder monitor camera, with same calibration frames and same stretch gives the same result. This is still consistent to me.
However, when I use this same stored exposure in live stack as single frame (via folder monitor), with the same dark and flat files, with the same extreme stretch in the camera control panel, I get significant larger and more hot pixel clusters, and a visible layer background noise. The stretch controls of the live stack histogram are left at default. I get similar result when I reset to camera control panel histogram controls,and use the live stack histogram controls. (slightly more noise though)
Doing live stack with same exposure settings and sensor temperature, I get similar result. Hot pixel clusters and visible background noise. Subsequent stacked frames reduce the background noise as expected. But the hot pixel clusters remain, some of them even grow. The hot pixel clusters are the reason I was looking into this.They show up in the stack and on a bad polar alignment day....
Is there an explanation for this? Is the live stack view at a larger bit depth? I don't mind about the very low level noise, but the hot pixel clusters are really annoying me.
Kind regards,
Rob.