The "No EQ" DSO Challenge!

[happy-kat]

Thanks Steve. I am going to do a new process tomorrow and try a deconvolution trick that can sometimes help kill the CA.

[Nigel G]

Hey guys.

Star tools is coming along good, with quite a few new tools.

Has anyone tried the new 3D module in Star tools. It works very well with nebula, still trying to work out settings for galaxies atm.

It's great for FB posts, also 3D glasses or viewing on web browser.

Nige.

[happy-kat]

No I hadn't yet but I did download the latest beta today that Ivo just released. So fresh I wore my oven gloves to download.

I'll give the 3d a try on this reprocess I'm doing.

Edited February 14, 2020 by happy-kat

[happy-kat]

This is a reprocess of 2018 data taken with the ED50 and super heavy crop as I don't have a field flattener.

I don't think there is much left to wring out of these 51 lights, mainly 30 seconds and no calibration files. Need more data for the HDR module to work with for the central area.

[happy-kat]

There's some pretty strong algorithms on this Samsung phone that when viewing the above it eats the image so it looks pretty dark with a few stars, I process for my monitor and home viewing.

[happy-kat]

Having read more about autodev by Ivo on the startools forum I've used it more and really it is anything but auto dev, I've also watched Richard Konrad youtube and seen a few more approaches to take in general. Time to step out of the familiar and keep progressing. It must be cloudy!

Edited February 21, 2020 by happy-kat

[happy-kat]

It must be cloudy!!

Further reprocess of the same data. The best overall management of the CA and star bloat was achieved by using the Compose module but I could not get the colour into M42 though I used the same star mask with the colour module and processed as OSC. Basically create a mask on everything bar the effected CA stars and their bloat halo and invert it before going into the colour module. I used various masks through to suit what I was doing. The data does have a very strong weird light intrusion blemish as the LED street light reflected down my flocked lenses snood. Interesting the stars looks a bit artifact like in M42 but that is not present like that in the tiff, this is a png for upload.

 

On 12/02/2020 at 21:36, happy-kat said:

Whilst waiting for the cloud to go thought I would follow Steve and revisit old data to reprocess.

This was the version of the data only 18 minutes 54 lights a mix of 30 seconds 20 seconds 10 and 5, bias, flats and dark flats. Virtuoso mount, Q200mm lens f4 Canon 1100d

A restack of the same file list in DSS selecting no white balance, setting a reference frame and making sure other settings were correct.

New process using bleeding edge StarTools 1.6.386, I decided to leave the stars quite neutral and omitted them from my colour process. Both images binned 50% though I chose a different crop position.

Original process in Feb 2016

 

 

[Bishkek]

If anyone is still active here, I'm just moving from static tripod astrophotohraphy to piggyback astrophotohraphy using a Canon 600D attached to my nexstar 130slt mount. (I'm not going prime focus as I am not keen on fiddling with the mirror and bolts, and a Barlow restricts what little light can be seen through the intense light pollution.) As I live in Singapore, an extremely light polluted city ranking at bortle class 9, I have a question regarding my exposure and ISO. I can take 30s exposures without field rotation becoming prevalent. However I am unsure what ISO setting to be using. I am afraid that setting the ISO too low will cause me to lose details in the data I capture, and likewise if I set the ISO too high the pictures become almost completely red. For reference, an ISO of 400 at 30s will already start giving me a pretty strong red tinge in my photos. I am aware that nothing can be done to fix the absolutely abysmal sky conditions, so I guess it boils down to which is will cause less detail loss. Should I stick to the lower ISO and lose some fainter detail and get less red skies, or crank up the ISO to try and maximise the detail captured at the cost of having very red skies and attempt to fix it in post?  

[happy-kat]

Your light histogram should drive your Iso selection and not colour, you want the peak completely clear of the left edge.

[rotatux]

On 22/02/2020 at 23:01, Bishkek said:

I am aware that nothing can be done to fix the absolutely abysmal sky conditions

Only partly true: did you try a light pollution filter ? I think of the so-called moon & skyglow kind, aka didymium / neodymium; It is cheap, and filters out enough that color balance is a bit better; And you can mount a astro-2" one on a lens with an adapter. For mounting directly on-lens, search for a used or new redhancer / red enhancer model (same filter material, usually for capturing autumn colors).

Just a detail about "histogram clearing the left edge" technique, it works but you need to account for the fact that on many cameras the histogram is an average of 3 channels, so you need to make enough space on the left that all 3 channels are (heuristically) cleared at the same time.

Edit: and of course the most efficient against LP is Narrow Band imaging but you have to deal with much longer exposures (and hardware setup to achieve it).

Edited February 25, 2020 by rotatux

[BrendanC]

There are things wrong with this image - overexposed and non-round stars for example - but I thought I'd post it all the same.

[SteveNickolls]

On 22/02/2020 at 22:01, Bishkek said:

If anyone is still active here, I'm just moving from static tripod astrophotohraphy to piggyback astrophotohraphy using a Canon 600D attached to my nexstar 130slt mount. (I'm not going prime focus as I am not keen on fiddling with the mirror and bolts, and a Barlow restricts what little light can be seen through the intense light pollution.) As I live in Singapore, an extremely light polluted city ranking at bortle class 9, I have a question regarding my exposure and ISO. I can take 30s exposures without field rotation becoming prevalent. However I am unsure what ISO setting to be using. I am afraid that setting the ISO too low will cause me to lose details in the data I capture, and likewise if I set the ISO too high the pictures become almost completely red. For reference, an ISO of 400 at 30s will already start giving me a pretty strong red tinge in my photos. I am aware that nothing can be done to fix the absolutely abysmal sky conditions, so I guess it boils down to which is will cause less detail loss. Should I stick to the lower ISO and lose some fainter detail and get less red skies, or crank up the ISO to try and maximise the detail captured at the cost of having very red skies and attempt to fix it in post?  

Hi, thanks for posting. Yes it is frustrating imaging where light pollution dominates whatever you do to such an extent. As rotatux says a filter will help somewhat. You are also constrained by tbe alt-az mount field rotation and the build of your mount as to what duration of exposures you can achieve. 

The question of optimal exposure time is discussed in a video by Robin Glover (SharpCap) which I will send you a link when I'm on my main pc. You can work out the optimum exposure time if you know a few things, the SQM-L of your imaging location, the read noise of your camera, the f-ratio you want to image at and using Sharpcaps online tool (I will send you the link). It might offer you a means of optimising what you can image with using what you have and what might help you in the future.

As regards ISO a higher ISO just brightens the image you see (on live view), it does not collect anymore incoming light or make the sensor more sensitive. It is important to get the image away from the left hand side of the histogram on your cameras live view but overdoing ISO will  merely move tbe histogram more to tbe right giving  you less room to later stretch tbe stacked images. I tend to use an ISO of 400. I would advise testing different ISOs to see if you actually see much difference in the exposure time allowed and resulting image.

Perhaps the best you can do is to take plenty of short 30 second  images to improve the SNR of the stack as best you can within all tbe limitations you have. In the end light pollution is placing a very restrictive glass ceiling on your imaging.  I have a link to an article about short exposure imaging that may prove interesting to you which again I will send to you.

Cheers,

Steve

[SteveNickolls]

Hi, here's the video-

And the online ShsrpCap tool- http://tools.sharpcap.co.uk/

Finally Samir Kharusi's article- http://www.samirkharusi.net/sub-exposures.html

Look forward to seeing your future  images. 🙂

Cheers,

Steve

[Bishkek]

On 26/02/2020 at 15:45, SteveNickolls said:

Hi, here's the video-

And the online ShsrpCap tool- http://tools.sharpcap.co.uk/

Finally Samir Kharusi's article- http://www.samirkharusi.net/sub-exposures.html

Look forward to seeing your future  images. 🙂

Cheers,

Steve

Thanks so much for these resources! 

Some incredibly useful information in there. I think I will have to limit myself to 30s exposures given my situation. As some others have suggested, I might look into getting a LP filter, however as I am going to move abroad for university soon, I think I will hold off until after university starts to see if I have the time or funds to continue with AP. No point investing a lot now when I have to leave everything behind in a few months. 

I'm just a little confused as I have multiple targets on which I have taken up to 500 subs at 30s, However the signal and fuzziness does not seem to be getting any better than it was at 200 subs. Maybe I'm just terrible at processing (I use photoshop). Any advice or tips would be greatly appreciated. 

Heres some info if it would help: 

Im using a Canon 600D with a 70-200mm Telephoto lens piggybacked on my Nexstar 130SLT, all subs are of 30s (the most I can manage without any streaks). 

I stack using Sequator (more lenient than DSS and it rejects less subs) and post process in photoshop.

 

Btw loving some of the pictures on here, this thread is an absolute lifesaver

[The Admiral]

4 hours ago, Bishkek said:

however as I am going to move abroad for university soon, I think I will hold off until after university starts to see if I have the time or funds to continue with AP. No point investing a lot now when I have to leave everything behind in a few months.

That's a very sensible approach Bishkek, university life demands a lot in all sorts of ways. Good luck with your studies!

4 hours ago, Bishkek said:

I stack using Sequator (more lenient than DSS and it rejects less subs) and post process in photoshop.

Well, in a way that doesn't necessarily help. I tend to go through my subs and only stack those where I think there is minimal streaking, although I did use DSS originally. I found that there is quite a variation in sub quality with my Nexstar mount. You can only get out what you put in!

Also, I'm not sure how you are using PS, but you ought to be stretching linear data and certainly not JPEGs. In other words, you should be stacking the RAWs. Is that what Sequator does? Photoshop can be successfully used (as can the free GIMP program), although I've not done so. I use Startools, a very powerful program but not expensive. However, you might not like its modus operandum.

Ian

Edited March 1, 2020 by The Admiral

[SteveNickolls]

5 hours ago, Bishkek said:

as I am going to move abroad for university soon, I think I will hold off until after university starts to see if I have the time or funds to continue with AP.

Hi Bishtek, I'm pleased the links were of value. When you have to image under light pollution you have this imposed ceiling of skyfog as the limiting factor in all the work. However not all is lost as developments in filters, camera's with higher quantum efficiencies and fast optics can bring reasonable results within your grasp on modest equipment. As you are off to university you might find opportunity to image especially if the local conditions are better than at home. There may well be an astronomy club at the university or a local town or a nearby dark site. It's amazing to realise the advances made in the past 3-4 years in the hobby so who knows what position you will be in after your studies to buy equipment not conceived of yet?

Best of luck with your studies.

Cheers,
Steve

[happy-kat]

I've used sequator and don't find the output as good as DSS, it's great when the image includes foreground like a starry landscape. You can use DSS score and FHMW after registering to help you decide the images to exclude from the stack.

[BrendanC]

25 minutes of M44, 60 frames, 50 bias, 50 darks, no flats.

 

[happy-kat]

You've got nice star colours in there, it's a lovely visual target as well.

[BrendanC]

Thanks! It's a nice cluster isn't it? Although I was confused when I realised there are two Beehive Clusters, M44 and M48! I thought I'd find stars and clusters a bit dull compared to planets, galaxies and nebulae, but they're strangely satisfying with those colours. The colour was brought out when I post-processed in StarTools and Photoshop.

Edited March 6, 2020 by BrendanC

[Bishkek]

Well, after literally reading every single page of this thread for inspiration, motivation and pointers, I began fiddling with some settings in DSS, and I finally have some photos that I believe are worth sharing. These are still projects I would like to add more data to with more clear nights, but this is the season of eternal clouds here in Singapore. Although I'm not completely satisfied with these photos quite yet, I thought I would share my progress with this incredibly wise and helpful community. These pictures are all taken over multiple (at least 3-4) nights, as there is practically no such thing as a house with a backyard in Singapore unless you are a multi-millionaire. So, I have a narrow window to photograph each target through my apartment window every night in the city lights, so all things considered, I'm pretty stoked I managed to capture anything at all. All subs are 30s, with darks and flats taken too, through my Canon 600D with a 75-200mm lens. I had to upload as jpeg as the tiff files were too large.

The crab nebula is 1.2 hours of data taken through my telephoto lens piggybacked on my 130SLT Alt Az, processed in PS. I think I need to add more data to this one to get some more of that detail and colour out of it. 

The Orion Nebula is 1.5 hours of data, same setup, processed in Pixinsight. The obvious go-to for any beginner. 

The third is NGC2903 in Leo, 3.5 hours of data, processed in PS. I think this one is limited more by the focal length of my lens than anything else, as I began to notice very little increase in SNR after about 2.5 hours of data, but I was glad to see that galaxies can be photographed with this humble setup. Most of them are bigger than I thought they would be.

Finally the Pleiades Cluster. This one was a big struggle for some reason. I was trying to get the nebulosity out of it for quite some time, and I was very pleased that I was finally able to bring out some of the glow from the nebulosity not just around Merope, but Alcyone and Maia too. I dont know if adding more data to this one would help too much, as this is already around 3.5 hours of integration processed in PS. I added my 30s subs to my existing fixed tripod subs (1102 x 2.5s) to get a total of 3.5 hours of exposure. 

Pretty much none of these objects apart from the stars of the Pleiades and the core of M42 are visible visually from where I live, so this was pretty much the first time I was seeing any of these objects for myself without looking them up online. I have a few more projects that I'm still acquiring data for, just have to wait for those rare clear nights. 

Sorry for the long post. 

Edited March 8, 2020 by Bishkek

[BrendanC]

Given I spent several hours in the cold the other night getting 2 hours' worth of exposures of M81, M82 and the Garland Galaxy, I thought I'd share it. 50 darks, 50 biases, no flats, taken with a Sky-Watcher 130PDS, on a Sky-Watcher AZ Goto mount, with a modded Canon EOS1000D and coma corrector, stacked in DSS, post-processing in StarTools and Photoshop.

[happy-kat]

Great to see the recent posts above and that we can image in challenging environments be it light pollution or cold, the mount is not a barrier to this.

[The Admiral]

1 hour ago, BrendanC said:

Given I spent several hours in the cold the other night getting 2 hours' worth of exposures of M81, M82 and the Garland Galaxy, I thought I'd share it.

Very nice too Brendan. You should be pleased with that. What sub length did you use?

Ian

[BrendanC]

Ah yes, sorry, should have said, subs were 30 seconds each, ISO1600.

This is the other story of the night: