M31 - 1st attempt

[LouisJB]

Well second attempt really, but 1st properly in prime focus, my very first shot through the 130P was through a x2 barlow.

Sorry about the coma, will be upgrading tube soon and then I'll get a CC

I have a question. I took a few images at 5 mins (resulting in the above) and some at lower length exposure. The longer 5 min ones looked a bit washed out on the camera screen so that's why for the rest I dropped the exposure time down to try and stop the gray/orange background.

When I processed them, I think there was more data in the longer exposures as they seem to produce better results after adjusting the levels etc.

So, is it ok to capture with quite a light background due to longer exposures and then process that out after, is that generally going to give better results? If so then I shouldn't worry too much about the lightness of the background on the camera preview screen? Also, how do you know when the light background is going to be too much?

I suppose the other question is the core, so bright - do I have to combine shorter exposures with layering to improve that, or am I basically overexposing the whole thing and should get more subs at a shorter exposure time?

Any advice much appreciated. I thought this would be an easy target, or maybe it is and I'm just not there yet.

[Leveye]

Excellent work! I would think about just making this into a b&w try red green and yellow filters to bring even more details out.

[Leveye]

Also take some of the highs out and recover the core a bit.

[LouisJB]

Hi, 

I've converted to greyscale and fiddled with the levels, I don't seem to be able to get the core much better (not really sure what I'm doing yet), but I may have a single shorter exposure so maybe I can layer blend the core in from that. I just learnt that technique yesterday on M42 core Trap so I can give it a go when I get a spare minute.

Also with the new levels, maybe I lost some of the wispy edges, but the black is blacker.

When you say Red, Green and Yellow filters - do you mean in photoshop or on the camera? I don't know how to do that in photoshop if that's what you mean, for the camera I don't have any filters or a filter wheel setup, this is just raw onto my DSLR.

I'll certainly give the filters a go if I can understand how. Here is the revised version.

Is it normal to spend as much time post-processing as capturing the data? It's not a fast hobby is it, but very satisfying when it works

[jambouk]

It looks good to me, but i'm not a deep sky imager.

If you'd rotated the camera to get te galaxy log axis landscape, would you still have captured the lower right galaxy too (is that m110 or m32, i never remember).

But looks smashing. It's the processing stuff which puts me off deep sky imaging.

James

[LouisJB]

thanks. I'm going to reprocess this data as I think I can get a better result from it. It's all good practice. The only good thing about the processing is you get to play around with what you saw and captured later, when it's cloudy (more often than not here it seems) and during the day too. Also I've discovered while imaging I can go indoors and warm up, line up say 5 or 10 long exposures then go put the kettle on.

Still, I could do with 2 scopes so I can use one visually while the other images... where will it end.

Unfortunately my current tube and camera setup is so primitive I can only get prime focus with the camera screwed directly to the focuser (minimum light path) - which means it's kind of at whatever angle it stops at when you tighten it up!

This problem + need for a coma correction is one of the main reasons for me wanting a new OTA - something with a decent 2" focuser and sufficient back focus for a coma corrector etc in the light path and I should be laughing. This is all a bit of practice until then.

I've just to decide what to get next, a newt F5, a refractor maybe, what size and focal length - almost impossible to decide but I'll have to get something better and then see how I like it.

[LouisJB]

I reprocessed the data to see if I could get a better result. I think it's a bit better. If it wasn't so cloudy all the tine I'd have got better data to play with already, but until then...

The core is a bit of a mess, still this was my 1st go at M31. Hopefully the next will be better.

[iksobarg]

I love when you guys say stuff like, "the core is a mess."

Brother, if it's a mess, it's a beautiful mess to me.

Next image please!! Chop, chop!! JK!

[ollypenrice]

The core of M31 is pretty difficult. Search the web and see how far in other imagers manage to get. You're doing OK in my view. My own best effort doesn't get much further in than yours. http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-3D2Hw7s/0/X3/M31%20Outer%20Halo-X3.jpg

Why the Barlow? It has reduced your field of view, so cropping the target. But maybe it is the only way you can get your scope to focus? If so, ignore me.

Taking the first image I'd have a look at the colour balance and try to get the top left of the histogram peaks to line up in each channel, like this;

Olly

Edit; I made an unfortunate typo on the word focus! 

[Pete Presland]

a nice start, plenty of detail coming through

[Tommohawk]

What a great picture! Did you take that with a 130P? Looks fantastic.

I bought a Skywatcher 150p last weekend, and used it for the first time tonight. Good views of Jupiter + moons with standard 10mm EP and x2 Barlow.

But Orion neb and Andromeda both looked pretty poor. I notice you're also in Sussex - ! wonder if you had a look tonight. Was it just poor seeing maybe?

[LouisJB]

thanks for the feedback everyone.

It was with a 130P yes. I can't remember but I think it was not barlowed - but the crappy way the camera has to screw into the focuser thread it tightens up to some random angle, which meant the image wasn't central, was using the height not full width of the sensor and was cut off on one side (poor planing on my part really, was first go with this particular setup) - also I had no coma corrector either, so I've cropped it down so that it's cut off is about equal on each side so it looked more balanced, otherwise it just looked odd being off to the side of the frame and chopped off!

Oh well, live and learn

Olly, thanks for the advice, much appreciated. Is that RGB alignment something I should do in photoshop? I'm not really that familiar with how to best process, experimenting and learning as I go at the moment. I ended up turning this one to greyscale because there wasn't enough data to make colour worthwhile. Your picture is fantastic, love that the colours come through. Hopefully I'll get better, it's a bit of a learning curve isn't it, have to start by making lesser pictures and find the way to make decent ones over time.

I have a better tube setup now, but at 1000mm it's not going to be well suited to the size of M31, I have however have a 200mm and a 300mm camera lens - I might try sometime with those before I get an ED80 or maybe 130/150PDS - Looks like I'll be ending up with a few tubes, but the current 130P will have to go as although I got prime working by modifying the mirror the focuser arrangement just isn't any good, need at least the 2" focuser (something I'd not appreciated when I started out).

Also I have since got a coma corrector now too, but that can't be used with the 130P either. Think this means I'll definitely be needing a replacement widefield scope for imaging only at some stage soon. On next clear skies I'll be experimenting with the 200 for imaging some smaller galaxies, I'll see how that pans out before thinking about what else I might need.

thanks again, all advise and feedback is invaluable!

[Tommohawk]

OP - Louis (?) Would be grateful if you could look at a couple of questions re your M31 pic.

I've just got set up ad had a go at M31 last night but nothing like as good as yours! Today I cleaned the mirror (think I got away with it) later will collimate.

Also I had the Nikon noise reduction switch on - maybe better without this. Also shot in JPEG, cos dont have RAW editor. I think my polar alignment was a bit off too.

So, can you remember what time exposure that pic was at? From what you say < 5mins?

Also, what camera ? Was it RAW image?

Also, what mount/drive were you using?

I think I shot at 3 mins - but have just noticed the tag shows 30 secs. Bit odd - maybe the max it can show even when exposure was longer.

Thanks

Tom

[LouisJB]

Hi, no problem.

From what I remember the original was about 3 minutes, but it would have been several 3min subs, stacked (not that that made a huge difference but it might if you've much noise etc).

At ISO 1600 IIRC

Camera - Pentax K5 (APS-C) - all built-in NR etc turned off.

Yes RAW, only use RAW, especially if you plan to stack or post-process, which nearly all astro needs/requires!

Scope 130P (with moved primary so I can get focus) - no coma correct at the time

Mount - HEQ5 Pro

The last image I did is the same data, but I reprocesed and chucked in the 5min exposures I had too, which I think brought out some additional detail not in the original.

I've very easy to lose M31 into the background, especially at the edges. Still that's probably true of any DSO. Probably next time I'll try to collect at least twice the data and hopefully really bring out some details.

All a bit of a learning curve, including the processing side.

I'd suggest, shoot many exposures, as long as you can until you get trails or light pollution kills the background. 

Shoot in RAW, turn all NR off. If you can take some darks too.

Stack in Deep Sky Stacker

Then adjust the result in something like photoshop, tweak the RGB levels and maybe the curves.

Very few of my images start with a very dark background, processing helps recover it. Maybe if you live in a darker sky area you'll get better results from the start, but I'm tending to pick up light pollution when I up the exposure over 3-4 mins, about 6 mins is the most I've attempted so far, then it was something nice and high in the sky.

Hope that helps! Good luck.

[russp]

I got 30 2 minute subs (ISO 800) on M31 last night (I don't have guiding set up yet so wanted to restrict length) on my Nikon 5200. (My very first attempt at deep sky)  I set DSS going last night about midnight and this morning it was on 15 out of 30 and I'd exported images as tiffs as it wouldn't recognise my RAW format - I guess thats what happens with 24Mp 16 bit images! Looking forward to seeing what I get when I get home later and playing with it but if I can get something approaching what you've managed I'll be a very happy bunny.

[Russe]

Hi,

I've converted to greyscale and fiddled with the levels, I don't seem to be able to get the core much better (not really sure what I'm doing yet), but I may have a single shorter exposure so maybe I can layer blend the core in from that. I just learnt that technique yesterday on M42 core Trap so I can give it a go when I get a spare minute.

Also with the new levels, maybe I lost some of the wispy edges, but the black is blacker.

When you say Red, Green and Yellow filters - do you mean in photoshop or on the camera? I don't know how to do that in photoshop if that's what you mean, for the camera I don't have any filters or a filter wheel setup, this is just raw onto my DSLR.

I'll certainly give the filters a go if I can understand how. Here is the revised version.

Is it normal to spend as much time post-processing as capturing the data? It's not a fast hobby is it, but very satisfying when it works

You spend more time processing than on capturing...

Sometimes many more attempts until you get it right...

[Tommohawk]

Hi, no problem.

From what I remember the original was about 3 minutes, but it would have been several 3min subs, stacked (not that that made a huge difference but it might if you've much noise etc).

At ISO 1600 IIRC

Camera - Pentax K5 (APS-C) - all built-in NR etc turned off.

Yes RAW, only use RAW, especially if you plan to stack or post-process, which nearly all astro needs/requires!

Scope 130P (with moved primary so I can get focus) - no coma correct at the time

Mount - HEQ5 Pro

The last image I did is the same data, but I reprocesed and chucked in the 5min exposures I had too, which I think brought out some additional detail not in the original.

I've very easy to lose M31 into the background, especially at the edges. Still that's probably true of any DSO. Probably next time I'll try to collect at least twice the data and hopefully really bring out some details.

All a bit of a learning curve, including the processing side.

I'd suggest, shoot many exposures, as long as you can until you get trails or light pollution kills the background. 

Shoot in RAW, turn all NR off. If you can take some darks too.

Stack in Deep Sky Stacker

Then adjust the result in something like photoshop, tweak the RGB levels and maybe the curves.

Very few of my images start with a very dark background, processing helps recover it. Maybe if you live in a darker sky area you'll get better results from the start, but I'm tending to pick up light pollution when I up the exposure over 3-4 mins, about 6 mins is the most I've attempted so far, then it was something nice and high in the sky.

Hope that helps! Good luck.

Brilliant. Thanks for taking the time to give such a detailed reply. I don't think I can be getting too much LP here, so should be able to do OK. I played around with Avistack a bit, but found it slow - completely stopped sometimes. So will get DSS, and try that with RAW.

Not sure when the next clear sky will be though! I'lll post my effort, so long as it isnt too embarrasing!!

Cheers, Tom