M101 – Another attempt but somewhat disillusioned

[matthasboldlygone]

Here is another attempt at the Pinwheel galaxy. Not much better than my first attempt which I knew I had made mistakes with. Bit of a let-down really, but I have photographed something 21 million light-years away so maybe I shouldn’t be upset. Messier would have been very excited with my image.

I suspect spending too much time on forums looking at everyone else’s perfect images doesn’t help. You know the posts – this is my first dso, but that one pixel doesn’t look right, I look at it and think it’s amazing crystal clear image. Not enough noobs posting fuzzy dud images maybe. Show us your worse images.

Bresser AR 102/600 achromatic refractor (£250 from Amazon with EQ3 mount)
Bresser HD camera (£280, Sony IMX290 chip and same specs as ZWO ASI290 but I think only outputs 8 bit tiff or jpg, no raw?)
HEQ5 Pro mount with Rowan belt (£900)
Capture software – Mac OSX ToupLite
Processed in Siril and stretched to near infinity with Photoshop.

45 x 2 minute exposures, 5 darks, Gain 5 (on a scale of 0-50 in ToupLite)
80 x 1 minute exposures, 5 darks, Gain 14 (taken on the previous night)
2 good sessions, 3 failed sessions due to clouds coming over. Total playtime 14 hours over 5 nights.
Target was maybe 40 degrees above horizon.
Bortle 4 on outskirts of Bortle 7 city and shooting towards the city glow.

So now I’m thinking where do I go from here?

Gain – ramp it up to capture more detail, but the noise increases rapidly if I try that.

Focus – is probably slightly out but with the stiff rack and pinion focuser I’m not sure I can get any better. Maybe time for a Bahtinov mask and spend more than the scope cost buying the upgraded focuser?

Camera and scope matching – seems quite good, 1 arc second per pixel, nice size in frame. Maybe the ASI 290 would give better results?

Upgrade the scope - Sky-Watcher Evostar 80 DS-PRO ED maybe?

Or spend another £3k on my flexible friend and upgrade everything? Copy someone else’s setup so I know what to expect.

Where would you say my limitations are? Scope, camera, capture or processing? Or just general user error, keep with it all and the images will improve with experience?

🤔
 

[vlaiv]

3 minutes ago, matthasboldlygone said:

Gain – ramp it up to capture more detail, but the noise increases rapidly if I try that.

This will do almost nothing. Gain is just conversion factor between number of captured photons / electrons and numerical value that you get when reading image off camera.

There are somethings related to gain settings (like level of read noise and such) - but you are not there yet.

4 minutes ago, matthasboldlygone said:

Focus – is probably slightly out but with the stiff rack and pinion focuser I’m not sure I can get any better. Maybe time for a Bahtinov mask and spend more than the scope cost buying the upgraded focuser?

Your focus seems pretty good to me. Slight problem with star sizes that you see is due to telescope used - fast achromatic refractor.

5 minutes ago, matthasboldlygone said:

Camera and scope matching – seems quite good, 1 arc second per pixel, nice size in frame. Maybe the ASI 290 would give better results?

This is certainly something to consider. If you are currently at 1"/px - you are way high in resolution for the telescope that you are using. ASI290 will be the same camera (except for raw performance - and that is important).

If these are cameras without cooling (and I suspect they are) - just get second hand DSLR camera. It will be less expensive and will serve you better. You can keep the camera you have once you decide to guide.

8 minutes ago, matthasboldlygone said:

Upgrade the scope - Sky-Watcher Evostar 80 DS-PRO ED maybe?

Yes, that will be good if you want to do better images. That will reduce chromatic aberration. If you want to keep current setup / camera - getting 130PDS as imaging scope will produce nicer looking image.

9 minutes ago, matthasboldlygone said:

Or spend another £3k on my flexible friend and upgrade everything? Copy someone else’s setup so I know what to expect.

Not sure if that is necessary. Even £1370 will get you gear that will provide you with exceptional results:

https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html

~ £230

https://www.firstlightoptics.com/zwo-cameras/zwo-asi-294mc-pro-usb-30-cooled-colour-camera.html

~ £1010

https://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

~ £130

[teoria_del_big_bang]

I certainly have seen much worse images so try not to get disillusioned for too long, I really think it still is an achievement.

I am by no means expert in any of this having only been doing this for just over 2 years have also had bad sessions and issues at times I do not know how to overcome at the time and often have looked at my data and think why do I bother. And I am sure everyone on this forum has been there at some stage and it will happen again from time to time.  But with great advice ( also often from @vlaiv ) I have always overcome these issues. Nobody on this forum has ever told me this hobby was easy though, but that is part of the challenge and definitely makes it all the better when something goes just right.

 Some great advice above and I am sure after a rest you will be back with improvements and you will be glad you persevered 🙂.

I look forward to your next images.

Steve

Edited August 10, 2020 by teoria_del_big_bang

[alacant]

5 hours ago, matthasboldlygone said:

spend another £3k

Hi

That would enable you to move closer to your expectations.

Add a heavy mount and guide telescope to that which @vlaiv lists and you'd not be much over your 3k budget. If you have sufficient clear sky opportunities then I'd go for it.

Your image is however very good given the limitations of your telescope.

Cheers

[matthasboldlygone]

@vlaiv Thanks for your suggestions, lots to think about while I'm sitting in the dark garden. I did think about a reflector but thought it may introduce more hassles, mirrors, dew magnet and collimation. But I'll certainly consider it now. Maybe a good stepping stone on my way somewhere.

Trying again now, increased the gain and adjusted the focus, but may not have that much difference after reading your post. We'll see what I get out of it later.

👍

[matthasboldlygone]

4 hours ago, teoria_del_big_bang said:

I am sure after a rest you will be back with improvements and you will be glad you persevered 🙂.

I think the sleep deprivation may have something to do with it, but I'm out here again in the dark. Good time to catch up with some podcasts. 😁

[matthasboldlygone]

1 hour ago, alacant said:

Add a heavy mount and guide telescope to that which @vlaiv lists and you'd not be much over your 3k budget. If you have sufficient clear sky opportunities then I'd go for it.

Damn, I almost got the neq6, but thought nah I'll never need that. Surprising how quickly you can rack up the weight of kit. Had a good run of clear sky lately, but expecting that to end soon. We'll see 👍

[michael8554]

Hi Matt

Lots of suggestions so far - different scope, camera, mount etc

What do YOU think is lacking in your images ?

That will help determine what needs upgrading, if anything.

M101 is a dim object to start with, try something brighter like M81/M82 before beating yourself up.

Michael

[Hallingskies]

M101 is not an easy target and I think your image is pretty good.  It nearly always comes out a bit fuzzy, even in all but the very best shots taken with large aperture high resolution kit.   Only thing I would suggest based on your write-up is to go for longer subs, your HEQ5 should be capable of 5min subs or longer and is a very good mount.  Sky conditions need to be pretty good as well, the slightest bit of haze blows out details in the core and arms.  You probably need to wait until M101 is overhead to give yourself the best chance of getting the most out of it.

Try your imaging rig out on a few less demanding targets (e.g. M81/82, M42, M27, M13) and see what your results are like before spiralling into the never-ending cycle of kit upgrades...

[matthasboldlygone]

1 hour ago, michael8554 said:

What do YOU think is lacking in your images ?

I felt it was a little hazy and fuzzy. I'd like a bit more detail / contrast in the cloudy stuff, and a few more of the bright stars in the structure to pop out. But after looking at some other examples I can see they all suffer a bit from those issues. 

Maybe I'll give M81 a go next time, or find another target a bit higher in the sky. Choosing the right target at the right time is something I need to think more about. 

[matthasboldlygone]

1 hour ago, Hallingskies said:

Try your imaging rig out on a few less demanding targets (e.g. M81/82, M42, M27, M13) and see what your results are like before spiralling into the never-ending cycle of kit upgrades...

Good advice, I'd like to max out what's possible with what I have before going further. 

I've been trying a few 5 minute exposures but getting stretched stars, periodic error maybe? I was thinking a good upgrade would be a guide scope / camera to get those nice long exposures.

[michael8554]

You may not have realised that many of the M101 images you've seen all started out looking like your image.

Then the Image Processing magic happened.

Agreed on guiding as a good next step.

An OAG will be less expensive than a guidescope, rings, mounting plates etc, and will be suitable for almost every future setup you get.

Michael

Edited August 11, 2020 by michael8554

[dannybgoode]

19 hours ago, matthasboldlygone said:

but I have photographed something 21 million light-years away so maybe I shouldn’t be upset.

This is key.  How many people do you know that have done something similar?  AP isn't easy, it isn't easy a bit tricky - it is very hard, especially to get a really good image.  I have been trying for well over a year (and nearer two) and am only just starting to get results I am pleased with and even then there is a long way for me to go.  

Just keep at it, keep practicing and you will get better.  The things that helped me get better images were guiding, focusing and processing with processing being the area that has made most difference.  I bit the bullet, bought PixInsight and have been trying to learn it ever since.  I can do the basics and it has improved what I can drag out of the mediocre data I have.  Whether you want to go the PixInsight route or not is up to you but definitely spend some time trying to learn better processing techniques and keep revisiting old data to see what you can tease out.

As to next kit I would definitely look at guiding and personally, having looked at an OAG solution think a standalone guide scope and camera is the better way forward.  I got this kit and it's excellent although you may be able to use your current camera as the guide camera and just get the scope:

https://www.altairastro.com/altair-60mm-guide-scope--gpcam2-mono-camera-combo-with-polar-alignment-assist-75-p.asp 

The 150PDS that has been suggested to you is a solid scope - I have the short tube P version which is very similar and a nice scope to use.  Big enough to be useful, small enough to be manageable and I will bow to other people's better knowledge of suitable cameras .

[vlaiv]

here is comparison image:

I took this one when I was at the beginning, but somewhat different gear was involved. Conditions are different as well.

Differences to your image would be:

- Sampling rate. Small scopes simply can't resolve 1"/px. With 100mm scope you need to aim to about 1.7"/px at best

- Maybe slightly larger sensor  - above image was taken with ASI178

- Scope without chromatic aberration - TS80 photoline F/6 apo

- Same mount, but I think I guided mine.

This is 8h worth of data from bortle 7-8 skies (SQM around 18.5), but I used cooled camera. Processing is not the best and there is gradient evident due to LP.

 

[ollypenrice]

1 hour ago, matthasboldlygone said:

I felt it was a little hazy and fuzzy. I'd like a bit more detail / contrast in the cloudy stuff, and a few more of the bright stars in the structure to pop out. But after looking at some other examples I can see they all suffer a bit from those issues. 

Maybe I'll give M81 a go next time, or find another target a bit higher in the sky. Choosing the right target at the right time is something I need to think more about. 

The results below give an insight into the imaging process. The final image had about 30 hours total exposure in Ha LRGB. If we start with the luminance only, this is what a simple log stretch on its own delivered. (This is a crop of just the central region since you're interested in sharp detail.)

As you can see, it is quite soft and fuzzy. However, the final image ended up with a core like this:

 

It's a lot sharper and more contrasty. So, as others have said, a great deal of the final detail is teased out in post-processing. It's not 'invented' in post processing. We can be sure of this because the same features are revealed time and again in high resolution images of this target. The aperture used for this was larger than yours at 140mm but was still a modest aperture. But here's the rub: you can only sharpen, stretch and otherwise aggressively process deep data with a good signal to noise ratio. If you over-process a weak data set it soon breaks down into noise.  If you simply had a lot more of what you have already you could take it much further. 

HEQ5, small apo or imaging Newt, cooled CMOS astro camera. This could come in on budget. (On SGL being 'on budget' always means about 25% over the stated budget.🤣But we mean well...)

Olly

Edited August 11, 2020 by ollypenrice
Typo

[matthasboldlygone]

On 11/08/2020 at 12:39, vlaiv said:

here is comparison image:

 

I'd be happy with that one. I can see my expectations of 1-2 hours are too high, tried stacking everything I've collected so far, maybe 3 hours and it's getting there in a way. 

[matthasboldlygone]

On 11/08/2020 at 13:51, ollypenrice said:

The final image had about 30 hours total exposure in Ha LRGB. 

Great images, 2 hours vs 30 hours, I can see I definitely need to increase the total time somewhat. A couple of hours isn't going to get what I want. 👍

[Chris33benoit]

Wow love those images of the Pinwheel.  Makes me want to do the same.  Good job!

[Viktiste]

Can you post the stacked image, but before doing anything else with it? 

[happy-kat]

What are you using to control your bresser hd camera, I don't see the capture software mentioned. 

[rnobleeddy]

I've not tried this target, but I've noticed a massive improvement when moving from no filter to a CLS filter (and for nebulae, a dual band filter).  I presume it's improving the SNR by removing some of the glow from the city lights.

 

 

[matthasboldlygone]

12 hours ago, Viktiste said:

Can you post the stacked image, but before doing anything else with it? 

I think I've deleted that one now, short on space... I'll look in the backup later and post if I can find it.

[matthasboldlygone]

5 hours ago, happy-kat said:

What are you using to control your bresser hd camera, I don't see the capture software mentioned. 

It was ToupLite on a Mac, but I wouldn't use it again, I think it compressed everything. Got better results with OACapture, but have now got a ZWO camera and asiair.

[matthasboldlygone]

4 hours ago, rnobleeddy said:

I've not tried this target, but I've noticed a massive improvement when moving from no filter to a CLS filter (and for nebulae, a dual band filter).  I presume it's improving the SNR by removing some of the glow from the city lights.

 

 

I'll be giving some filters a go soon, this was quite low in the sky towards big orange city lights. Not the best conditions.

[old_eyes]

As an early image, that's pretty good. I have an M51 image from my early experiments that looks similar, so don't give up.

As others have said, M101 is quite a difficult subject as it has a low surface brightness. I have never got an image of it from my own backyard with my own equipment that satifies me. However, I have got results that really please me (and wow friends and family!) on the Orion, Rosette, North America, Flaming Star, and Horsehead Nebulae. As well as targets like M31, M81 & M82, the Leo triplet and the Pleiades. Get the best out of your equipment on the easier targets and then work your way up.

It takes time. It really takes some time!

Good luck!