Author Topic: M31 - Learner's Image  (Read 355 times)

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JohnH

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M31 - Learner's Image
« on: Dec 16, 2019, 09:10:06 »


I have managed to point my camera to the sky again. This is my third deep sky image and I like to think I have made some progress.

The image was taken using a Star Adventurer Mini (and so unguided). My second hand camera zoom lens was set to 197mm and I have made a cardboard aperture so that it is close to f5.6. I used a ZWO 1600 Pro mono camera with a filter wheel and, a bold move given no GoTo, imaged on the 4th and 9th of December.

Processing is an even steeper learning curve than imaging! I calibrated, registered and stacked in Astropixel Processor and then used Pixinsight and Photoshop.

I have ended up with a surprising number of red stars (I have dropped saturation to make this image more credible).

I certainly look forward to more imaging and more processing practice.

(My browser will not show the image although it links to it - I think I need a complete and TOTAL idiots guide! Now successfully inserted by copying the BBEdit link from Imgur.)

JohnH
« Last Edit: Dec 16, 2019, 10:56:51 by JohnH »

The Thing

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Re: M31 - Learner's Image
« Reply #1 on: Dec 16, 2019, 10:02:38 »
Hi John,

Yes, no image. I can see from the web page source that its on Imgur -img src="https://imgur.com/a/LluG7PS" alt="" width="800" class="bbc_img resized"- is the tag you inserted and I can see the image on Imgur. I have inserted the image myself here ---img--- but I can't see it in the forum. One for the forum gurus, there seems to be an issue with Astrobin as well. Maybe the forum when upgraded recently was set to refuse requests to external websites or something????

Anyway, your M31 looks pretty good for unguided with a camera zoom at 200mm. I would try a at 100mm for this subject as most zooms aren't so good at there extremes, also tracking accurately and polar alignment become much more important. I would use SharpCap through your camera and lens to do the polar alignment to get is spot on, I do with my StarAdventurer. I think as you say, you are stretching it using a mono camera and filter wheel on such a setup as the imaging train is quite long and will be very unbalanced (or are you using the deluxe kit with counterweight?). I would try and get a fixed focal length lens as they tend to be better quality, I like Pentax ones myself.

Processing is a pig, I use PigsInside and I spend hours and hours following recipes and trying things and sometimes although the subs look great I can't get a nice result and give up and do a quick stack in DeepSKyStacker and tweak in GIMP. Keep plugging away!

HTH

Duncan


We're all guinea pigs in the laboratory of life. Better a fluffy guinea pig than a lab rat!
¯\_(ツ)_/¯ (Gallic shrug :))

Carole

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Re: M31 - Learner's Image
« Reply #2 on: Dec 16, 2019, 17:44:37 »
Well done, the image has a lot going for it, especially for a beginner.
The stars are not too bad at all considering you weren't guiding.

The processing does take a long time to learn, and even after all the years I have been at it, I am still learning new things.  Coping with APP, Pixinsight, Photoshop as well as all the equipment, is no mean feat for a new imager.

I don't use Pixinsight, so can't help you with that, but looking in Photoshop I can see you have clipped the black point.   This is meant as constructive comment as we probably all did this at the beginning.  i.e. you have tried to make the sky too dark and in so doing have lost some of the outer nebulosity.
You can tell by looking at the histogram which is against the "wall" on the left hand side. If you can bear to do so I'd try that again and see if it reveals more detail for the galaxy around the edge.

I have never been one for camera lens imaging and when i do I am rubbish at it, and I have not used a Star Adventurer.  I do however use a mono camera and filterwheel. You have combined the channels together exceptionally well.  I am inclined to agree with Duncan that this is probably a bit too heavy for the star adventurer unless you have the deluxe kit. 

Onwards and upwards.  Look forward to more from you, we don't seem to have as many imagers as we did once, so nice to have new ones on board.

Carole







Roberto

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Re: M31 - Learner's Image
« Reply #3 on: Dec 17, 2019, 15:08:52 »
Well done John!  That's an excellent image if you are just starting  8)  Stars are round and tight.

Roberto

JohnH

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Re: M31 - Learner's Image
« Reply #4 on: Dec 17, 2019, 17:38:13 »
Thank you everybody.

I am using the deluxe counterweight, my lens is 75mm - 300 mm and so I am roughly at the midpoint. I would rather use a fixed focal length but I couldn't find one.

My idea is to use this as a learning tool until I can get a space to conveniently store, and then actually use, a larger telescope.

I have done a remix which (I think) does not clip the dark pixels. I am not sure if I have managed to improve it though.

John

Carole

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Re: M31 - Learner's Image
« Reply #5 on: Dec 17, 2019, 18:42:11 »
One more tip.  With images such at M42 and M31, it is always a good idea to take shorter exposures for the core which can get burnt out easily, though combining the subs of different lengths brings it's own processing challenge.

I have managed to get away with M31 in the past with careful stretching and latering to p[revent burn out of the core, but it's not easy.

Carole

JohnH

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Re: M31 - Learner's Image
« Reply #6 on: Dec 24, 2019, 14:36:37 »
I have reprocessed this as much as I know how, that almost certainly means massively over processed but that is what learning is all about.

I have got the stars smaller, rounder  and less luridly coloured. However, it does feel too contrasty to me.

All said and done I am happy with the result given my lack of knowledge and the lens I have used. Thanks to everyone for nice comments and tips.



Merry Xmas,

John

Carole

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Re: M31 - Learner's Image
« Reply #7 on: Dec 24, 2019, 18:06:05 »
The outer detail in the galaxy is now revealing itself more. 
I know nothing about Pixinsight so can't advise there.

I didn't dislike the coloured star in the first process.

You might find this on-line video tutorial I made on basic levels and curves useful.
https://www.youtube.com/watch?v=LWqI_T4zAgM&t=2s

Carole