NGC7000 - First extended run with QHY268M

[AMcD]

Last night I managed to get my first extended run with the new QHY268M.  This image represents 4 hours 10 minutes of 600s integrations taken with a TS152 achromat through an Antlia 3n h-alpha filter under Bortle 5 skies with some passing high cloud.  Stacked with darks in DSS and process in PS. 

The stars leave a great deal to be desired as I am having peculiar issues with my mount/guiding, about which I have posted separately (and any ideas gratefully received): 

Edited September 22, 2022 by AMcD

[ollypenrice]

Smooth and delicate. Nice.

Olly

[AMcD]

23 hours ago, ollypenrice said:

Smooth and delicate. Nice.

Olly

Thanks Olly, that means a great deal coming from you.  The data is a joy to process.

[Richard_]

Nice work! Good to see that your back focus is spot on, the image is looking great! I told you the data is great to work with

600s is a long sub time for this camera and filter (unless your seeing conditions and light pollution permits longer subs, or you want to work with less files). Do you see any star trailing with shorter subs, say 300s? 

[AMcD]

1 minute ago, Richard_ said:

Do you see any star trailing with shorter subs, say 300s?

Spooky - I am doing that very test as we speak!  I still see some "eggyness" at 360s, albeit it is less pronounced than at 600s.  Strangely, the scope has just done a meridian flip and the stars look slightly better with the scope on the east side of the mount than they did on the west.

I no longer seem to be getting the more peculiar features of 'doubling up' and 'kidney beans'.  I re-cabled the set up today so that the collected cables now drop from the top of the counterweight bar per @ollypenrice's advice.  I also checked thoroughly again for loose fittings and other potential points of flexure.

I think it is coming down to an issue of either guiding or flexure or both.  The G11s can be difficult to 'dial in' when it comes to guiding and I have recently upgraded the worm blocks and motors.   I reseated the worms today, but I am going to send my logs to the PHD2 forum tomorrow.  The last time I had an issue, Brian Valente was able to give me a solution.  With respect to flexure, I have been looking at solutions today for mounting the guide scope with clamps rather than scope rings and attaching it to the side of the dovetail plate rather than on a plate on top of the main scope rings.  The guide scope rings are tight, but I never fully trust them.  I am also considering off-axis guiding but I understand that can have its challenges as well.   

I will solve it eventually...

😂

[Richard_]

52 minutes ago, AMcD said:

Spooky - I am doing that very test as we speak!  I still see some "eggyness" at 360s, albeit it is less pronounced than at 600s.  Strangely, the scope has just done a meridian flip and the stars look slightly better with the scope on the east side of the mount than they did on the west. 

I wonder if that's due to a balancing issue? With my mount (EQ6-R) the RA axis is a little sticky, so when I'm trying to balance it can be difficult to feel the fine differences in balance. If your G11 is similar, maybe that explains a subtle difference in balance. 

Does your mount have any type of Periodic Error Correction (PEC)? I found that my guiding improvement significantly after running a few PEC training cycles and enabling. 

[ollypenrice]

I've never liked guide rings and they serve no purpose these days. In the past you needed to head off-axis sometimes in order to find a star.

Olly

[AMcD]

19 hours ago, Richard_ said:

Does your mount have any type of Periodic Error Correction (PEC)? I found that my guiding improvement significantly after running a few PEC training cycles and enabling.

The G11 does have PEC.  I have always wondered whether the PEC would compete with PHD2 but I can see how they might in fact complement each other.   I will give it a go 😀

[ollypenrice]

23 minutes ago, AMcD said:

The G11 does have PEC.  I have always wondered whether the PEC would compete with PHD2 but I can see how they might in fact complement each other.   I will give it a go 😀

I've never combined them but I've read convincing arguments in favour of using both together if you have a problem.

Olly

[Richard_]

35 minutes ago, AMcD said:

The G11 does have PEC.  I have always wondered whether the PEC would compete with PHD2 but I can see how they might in fact complement each other.   I will give it a go 😀

Initially, I used to get guiding errors (total RMS) of 1.0 to 1.5 arcsecond on a regular basis. I started the PEC learning within the ASCOM software, and now when I guide with Tracking + PEC the total RMS is more like 0.5 to 1.0 arcseconds. What the PEC does is learn where the error is for each gear and compensates for it before it even affects your guiding. Therefore, PHD2 does not need to correct as much.

Check out this tutorial from Astrobloke who does an excellent job at talking through PEC training. Give it a try to see if it works for you