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M31 The Andromeda Galaxy (Part 2)


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I got some subs on this last week but it wasn't really enough to do much with

This is the first time I managed this one properly and it's some processing task! It's taken me about 4 hours to get to this point, I had to learn layer masking for the core detail using 60 sec subs and had some really big problems getting my flats to work and the subsequent gradients that happened. A combination of Noel's Actions and more layer masking saved the day

I would be interested to hear if people think this is overdone, I've got a habit of doing that I've got an itchy finger :D

Camera: QYH8 with Hutech IDAS LPS2 Filter

Scope: Skywatcher Equinox 80 with Televue TRF-2008

Mount: EQ6 with EQMOD

Guiding: Orion ST80 with QHY5

Capture Software: CCD Commander, The Sky, Maxim DL

Processing Software: DSS, Photoshop, Noise Ninja, Noel's Actions

Exposures: 16 x 600 secs (2 Hours 40 Mins), 11 x 60 secs (11 mins)

Calibration: 100 x Bias, 50 x Flats


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You've done a nice job with the layer masking and I like the colour. The dim outer stuff is going a long way out and the whole image is nicely framed.

The black point looks clipped on my work monitor (which clips the black anyway) and, for my taste, the smoothing has been overdone and this has affected the appearance of the main dust lane.

Overall it's a lovely image. You have lots of material for cloudy nights. A bad flat is worse than no flat so it might be worth trying without the flat subtraction.

Edited by MartinB
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Just to echo Martin's points there, everything in place for a first class image, but do go a little easier on the black point, make sure you dont pull it into the data spike when using the levels tool.

You might find it helpful with the qhy8 to set the black point for each colour channel independently, if using photoshop, once into the levels tool (CTRL+L) you can choose each channel with CTRL+1, CTRL+2 etc.

If you struggle with the flats, may be better to deal with vignetting through software, like Pixinsight LE. Cant beat a good flat though, especially with the dust bunny prone QHY8!



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My processing on this gives me wildly different results every time, here is another one that I'm much happier with.

OSC processing is a pain, I'm seriously considering going all NB :D


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The dust lane detail is way better in that one euan. I prefer the colour of the first though:rolleyes: If you can find a way of combining the best of the 2 you have yourself a winner!

OSC is no harder/easier to process than RGB really. In fact it's pretty much the same once you've calibrated and debayered. You just don't have a luminence to help you out although you can make one.

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  • 2 weeks later...

Here is (another) rework of this

This time using PixInsight to remove the gradients, rather than using Photoshop

I'm much happier with the colour balance and background


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Great stuff Euan, much better! As Harry says, you really should try the HDR wavelets tool. When I used it on my M31 data, it revealed dust detail literally right into the centre, stuff I never have seen there. I'll see if I can find the pic.

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Here you go Euan, just the cropped centre of some M31's I grabbed back in Sep. They were taken with the QHY8 as well, and were 600 second subs at f5.3. With the usual processing most of the core gets blown out, especially as we try and bring out all that fainter outer rim.

When Pixinsights HDR wavelet tool was applied, all the dust detail that you see magically reappeared out of the white. You can try the full app for free for 30 days too IIRC.

For what it is worth, I never feel really happy with M31 images, there is always somethng more you can do to them, at the expense of something else, and what tickles your fancy one day is different the next. Add to that the great variety of colours and styles that come through when you look at the pro's images and it all gets a bit much :)

Whats next on your list then? :)



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OK you were right :)

Here's one done with the HDR wavelets. I'm still trying to get used to it, but it seems quite powerful.

I've also started using DBE, which has meant I can keep the colour from draining out M31

What's next? I'm taking my time now since I spend months processing one image :)

Seriously though, I'm going to go back and try and get 6 hours on this once I've solved my gradient & flats problem. Then try this process again


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