M57 - my 1st AP attempt with new kit - any tips or comments?

[Adrian23]

Here is my 1st attempt at DSO AP using my new kit (a SW 80ED DS Pro on a VX mount coupled to a Canon 500d DSLR). I don't know if M57 is the best target for a newbie but it just seemed to be in the right place at the right time for me.

Any tips or comments would be greatly appreciated as I'm really keen to climb this steep learning curve that is DSO AP.

Here's a little background info to help you evaluate my effort a bit better:

• 10 x 60sec unguided lights (in my eagerness to start imagining I neglected to follow the ASPA routine for a really accurate polar alignment which is why I kept the subs to 60 secs; will certainly use ASPA next time to hopefully push the lights exposure time up a notch...)
• 10 x 60sec darks
• 5 flats
• 5 bias
• stacked in DSS
• levels adjusted in GIMP

I have had to heavily crop the final image to upload it to SGL (limited to 1Mb max)

One problem I DID encounter which someone might be able to help me with: I had real problems restoring any colour to M57 after the stacking in DSS. I tried following Steve Richards' really useful section on post-processing in "Making Every Photon Count"  but no matter how I tweeked the saturation using GIMP, I still could not get much colour back (each sub of M57 was a vivid blue). In the end, I started again in DSS and boosted the saturation there before moving on to GIMP to adjust the levels. Any ideas on how to bring back the colour in GIMP? As I understand its best to do all post-production away from DSS, or have I got that wrong?)

Really looking forward to your helpful comments and tips everyone...

Adrian

[andrewluck]

To start with I suggest using a fixed colour balance on the camera, I usually use Daylight. This gives more consistent results as the light level is too low for the camera to ever get it right. You didn't say what format you saved the pictures in but my advice is to always use RAW. This limits the processing that the camera does before the image is saved and preserves the original bit depth.

I believe you can increase the saturation in DSS before saving the image but I don't use that program so I'm not sure. I suggest an initial non-linear stretch in DSS though as GIMP is 8 bit only. Neutralise the background by adjusting the black points until the histogram peaks coincide, then you can decide if the colour balance looks right and adjust accordingly.

Larger targets will be a better match for your ED80 as M57 will only be tiny at that image scale. The late summer is my favourite time with big Milky Way wide fields being a good match for my 85mm.

Andrew

[Adrian23]

Thanks for the advise Andrew. I'll try all those points if I ever have another clear sky night that doesn't coincide with having to work the next day :-)

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[neil groves]

I would be super pleased with this image as my first attempt, love that vivid green.

I feel your pain about the clouds, compared to last year I am having an awful time with thin high cloud nearly every night, i'm hoping I don't have to wait for October when the weather cools down to get totally clear skies again, there are some targets coming up in the next few weeks I want to have a bash at.

Neil.

[PorkyB]

I don't make any adjustments in DSS.  I use it just for stacking.  I use GIMP for all my processing.

It's a good image with good tracking and focus, so you have a plenty to work with there.

I would save it from DSS with no changes applied and then use GIMP to stretch it a bit using Curves and then clear out the background noise with Levels.  If the colour needs adjusting there is the Hue-Saturation tool but you probably won't need it.

I have had a very colourful M57 with my Canon DSLR, so it certainly can be done.

What file format were you inputting to DSS (TIFF, CR2, etc.) ?

[lensman57]

You have done very well for a first attempt. The problem with M57 is that it is very popular with beginners in imaging ( like M42 ) but it is actually a very difficult target to image properly. One problem is that it is very small so to get a decent image scale you'd need about 2000mm of FL which in the ordinary world means an 8" SCT at native FL or a 12" with a 0.63 reducer . The second problem is that the main ring of the nebula is relatively bright but to capture the intricate and the very ellusive inner and outer halos you'd need to image it in a combination of NB and RGB with lenghty subs. 60s subs will not do and that is why you had difficulty getting the colour out of the stack as there is not eough signal. I suggest you do atleast 30 subs of 300s to start with once you have had PA and guiding sorted out and this might give you a chance to show some structure in the nebula. A very good first attempt none the less.

Regards,

A.G

PS: Try and not bother with adjustments in DSS, good for stacking but not much else IMHO.

[Thalestris24]

Hi

In the Stacking Settings -> Stacking Parameters - I leave 'Align RGB Channels in final image' unchecked

Louise

[Adrian23]

Thanks everyone. I'm taking all this advice down so hopefully next time I see some improvement. I'll show you all the results if the clouds ever part again. Think I'm gonna try the North American nebula next - what do you think as a target for a newbie???

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