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M13 RGB, experimenting with 30 second subs.


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Of course, the skies here aren't really dark at the moment but I could not resist trying out the new scheme (for me at least). This image is the result of 1.5hrs of 30 second subs. The outcome is easier control over clipping stars, fewer trashed frames and better star shapes at full resolution.


I have 30 mins of Lum but I'm not sure it will add much. I may try another round of processing to see if I can improve the contrast and less burn in the core. This image is a pretty much full frame with just dithering needing to be cropped out.  Imaging details: 250mm Newt on the CEM70G. Camera was ASI1600MM-Pro @ Gain 139, Offset 50. Guiding with a 60mm guide scope and ASI290mc (my planetary camera). Processed in PixInsight and finished in Paintshop Pro.


Guiding has been horrible the last two nights; I seem to have injected some misalignment as DEC keeps throwing a wobbly - I need to check my PA routine because when I have it right DEC doesn't need much adjustment at all. I would like subs on the scope to be longer than 30secs for narrow band so I need to iron this out.


As we had a second clear night I have some M92 subs to process, hopefully the data will be good🤞

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4 hours ago, AstronomyUkraine said:

Your star colour is great, and the core doesn't look too bad at all. I think your gain and offset are little high for globular clusters. Maybe an hour or so taking Lum data with a lower gain and offset will give you more detail in the cluster.

Thanks, I will look into other gain settings; I need to make sure the numbers add up for before I change my strategy🧐

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1 hour ago, Padraic M said:

Very nice result. I've done similar recently with 150s subs RGB, and I like your star shapes better. 

Thanks, but I had to use shorter subs to get them - so I'm cheating a bit😄


I think I tracked down my issues - a combination of re-calibrating my ipolar,  focusing the guidescope correctly(!) and pointing the guider closer to the target has given me much better RA tonight but I'm still seeing sporadic DEC jumps. I suspect its my over tweaking and resulting in a binding DEC, I might just back that off a bit.

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