What am I missing?

[PeterC65]

I've had two frustrating session at EEVA now and think I'm missing something. Last night I was using the Altair GPCAM2 327C camera with the Photoline 72 scope (72mm F6) with SharpCap software. I've read the manual up to an including the live stacking section and was using the histogram and live stacking tools.

I had great difficulty getting images of any DSO, and instead I was just seeing star fields. Looking at the histogram, I was getting a sharp peak at what I assume was the background black level and pretty much nothing else. See the screenshot below ...

Increasing the exposure time and or the gain widened the peak but only a little. This seems very different from the M42 reference image that comes with SharpCap.

When I used live stacking and used the auto stretch function in the live stacking histogram the image turned white. The black level had been set just to the left of the peak and it was as if that peak was washing out the whole image. To see anything I had to exclude the peak.

Should I be seeing just this sharp peak?

Why does including it in the live stack make the image turn white? Surely the peak is at low luminance so including it would be to include very dark pixels not white ones?

I switched cameras later to a Canon DSLR and had more success with this, but still got the dark peak.

 

[M40]

Just a thought in that have you looked at the field of view with your telescope and camera combination?

The only thing I have wide field enough to view M42 is a DSLR. Hope it helps.

[PeterC65]

I had a more successful session last night with the Altair GPCAM2 327C camera and the Photoline 72 scope. The sharp peak I was seeing in the histogram seems to be because I wasn't pointing at any DSO, just a star field, so mostly black background, hence the sharp peak.

Last night, after watching a video tutorial, I turned up the gain to maximum and used a 1 second exposure with some auto stretch to try to frame the DSO. I could just make out the DSO in most cases and when I could not I took a snapshot and submitted it to Astrometry.net to find out where I was actually pointing. Sometimes that helped, sometimes it didn't. I made a point of only progressing to live stacking if I was sure I was on target, then I increased the exposure time to 10 seconds reduced the gain to 200 and started live stacking with some good results I think.

M27

East Veil

Not fantastic astro photos but that's not what I'm aiming for. These took a couple of minutes to appear so not as live as I had beem hoping for but way better than straight visual.