M81 Bodes Galaxy

[cuivenion]

Scope: 200mm Super Takumar F4 M42 Lens (Stopped down to 5.4)

Mount: Skywatcher HEQ5

Imaging Camera: ZWO ASI224

Guiding: Altair Colour GPCAM on a Chinon 135mm lens

Software used was Sharpcap 3.2 for capture, PHD2 for guiding, DeepSkyStacker and Pixinsight for stacking and processing.

3 hours of 28 second subs

60 x darks

Taken in the early hours of Sunday morning. I may have another go at processing this at some point, I've struggled with this one. Comments and constructive criticisms welcome as ever.

 

[wimvb]

Nice! What colour calibration method did you use? Colours are a bit too pink, imo.

Sometimes photometric colour calibration results in colours that are a bit "off" after stretching. The standard colour calibration routine can give more pleasing colours.

[cuivenion]

Thanks wimvb. I tried three different settings in Photometric Colour Calibration, and the cast always seems to veer towards red when I stretch. I thought I'd tried colour calibration too but I'll give it another go.

[Jarvo]

Great image. The short exposure time over 3 hours shows what a great result can be achieved. I’m limited by light pollution and lack of guiding so will definitely be having a go this way next time I’m out. 

Thanks for sharing. 

Jarvo

[cuivenion]

Cheers Jarvo.

[cuivenion]

Here's an update. Colour Calibration was more accurate, but I still needed to nudge the red slightly in the histogram.

I may add more data to this at some point.

[wimvb]

Much better. As you say yourself, the next step is to add more data. The stars are a bit soft. How do you focus? A remedy in software is deconvolution before stretching and star reduction towards the very end of processing.

[cuivenion]

Hi, when I tried deconvolution on the stars I was left with a sharp central white point and a fuzzy halo. I did do deconvolution on the galaxy. I also did star reduction towards the end but if I took it too far some of the stars disappeared. I may have to do a different mask so I can perform it on just the larger stars first.

I find with focusing this lens that if I focus as well as possible I get violet CA, but if I'm out a tiny amount out there's no CA at all. I may have to  experiment with this. I focus using fwhm score in Sharpcap. I've tried bahtinov masks before but the reading just seems to jump about erratically so I don't trust it. Thanks for the replies.

[peter shah]

nicely done.... colour balanced version is much better

[cuivenion]

Thanks Peter.