BrendanC

Hi all,

A first for me last night - 300s subs, which requires a lot of background work to build the darks library but worth it. Managed to test it by adding exposure time to my Elephant's Trunk Nebula.

It was also my first proper shoot since fitting a primary mirror baffle which I think may have made quite a big difference to the star definition. 🙂

Nerdy stats:
* 7:39 hours of integration at ISO800 from top 90% of 17x120s + 50x240s + 45x300s subs, over 4 nights 
* Bortle 4 sky, Moon average 53% phase, 33° height 
* Calibration: 25 flats, 25 dark flats, 50 darks 
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount with Rowan belt, Canon EOS1000D DSLR camera with IR filter removed, Sky-Watcher 0.9x coma corrector, Datyson T7C guide camera, Angel Eyes 50mm guide scope 
* Software: Polar alignment with SharpCap Pro, guiding with PHD2, capture with Astrophotography Tool (APT), stacking with Deep Sky Stacker (DSS), post-processing with StarTools and Topaz Denoise AI

I gave up on APT's focus on tools and now use the standalone Bahtinov Grabber tool which, although APT's version is based on it, is actually much easier to use and more reliable. 

Found these, which seems to confirm that flat darks do just get swapped out with biases: https://discuss.pixls.us/t/dark-flats-processing/23784 and https://discuss.pixls.us/t/how-to-process-and-incorporate-dark-flat-frames/19271/5

Part of the problem is phrasing: sometimes they're called flat-darks, other times dark-flats, other times darks for flats!

Right, now I need to figure out how to do a script that allocates the right darks to the right lights... 

@Ricker Is Sirilic (if that's what you mean) Linux only? I'm running Windows 10. POST-EDIT - I found the Windows download. Finding stuff about Siril is not easy!

@GalaxyGael I'll sound the folk out on the Siril forum, I just tend to use StarGazers as my goto resource!

Hmmm, looking at the script, there's this: preprocess flat -bias=bias_stacked

Then, later, there's this: preprocess light -dark=dark_stacked -flat=pp_flat_stacked -cfa -equalize_cfa -debayer

This implies to me that the flats have the bias removed before the main preprocess - which is exactly the same workflow as for flat darks, right? In which case, substituting the flat darks into the bias folder should have worked. In which case, maybe I'm doing this right.

I don't know. My head hurts. I'm going to leave this until tomorrow, but thanks for the help in getting me this far!

Nice. I'll have a go! This is literally my first time actually getting Siril to do anything so I'll have to scratch my head a bit. But I do see how that might work. Really appreciate the help, thanks.

You're right, I don't think the maths would work. Thanks for this.

I have tried it but the results weren't great. 

There's no mention at all of flat darks or dark flats in the user guide or anywhere else that I can see. The only mention I've found close to this is here, as 'flat-dark images': https://staging.siril.org/faq/  However, it doesn't explain how to script this, and the scripts page it links to doesn't have any scripts that handle flat darks either.

I'm starting to wonder whether Siril does in fact handle flat darks at all, in which case I'll stop using it with immediate effect! It seems rather an astonishing omission.

Any more takers?

Hi all,

I've finally managed to get some sort of result out of Siril. I have a feeling that I'm on the verge of actually understanding how its scripts work and how to adapt them.

However, one thing stumps me: I use flat darks instead of bias frames, so how do I get Siril to do this?

If I just put my flat darks into the bias folder and let it process them, will that work?

Thanks. Brendan

It's a Datyson T7C, which is an ASI120MC clone (uses the same drivers). The pattern I'm selecting in Registax is GR - the only option that yields colour in the preview. I'm assuming that corresponds with GRBG which is what I've been selecting in PIPP.

Wow, great response, thank you! I'll check out Autostakkert. 

 i all,

I bring my PNG images into Registax 6, which appear in mono because they need debayering.

I select Show Pre-filter and select the option that correctly converts the images into colour (GR). 

I set align points, align, and then limit. Still all OK.

I stack. The final image is mono.

What am I doing wrong here? I cannot figure this out. I'm having to use PIPP as an intermediate step to debayer before going into Registax, but I'd rather do it all in one go with Registax because it's quicker and frankly uses a ton less storage space.

Thanks, Brendan

Hi all,

I don't often 'do' planets, but given that Saturn's close to opposition I thought I'd give it a go.

The results are underwhelming - as in, they're alright, but I expected better:

Details are:

* Best 50% of 2,000 frames
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount with Rowan belt, Datyson T7C (which is essentially a ZWO ASI120MC, uses the same drivers, which I usually use as a guide cam), Bresser 5x Barlow
* Software: Capture with Sharpcap, tracking with Stellarium, stacking and post-processing with Registax, PIPP, Topaz AI Denoise and Photoshop CS2

My questions are:

* Why is it so pink? Is it because it's low in the sky (this is from SE England)? Is it something to do with Registax or PIPP? (I had to use PIPP to debayer the output from Sharpcap, Registax wouldn't do it for some reason).I have a Jupiter shot from last week that, while I'm much more pleased with, is similarly a sort of red hue. This was taken using the Live View on my astro-modded DSLR and a 3x Barlow, so the optical train is quite different:

* Why is it so blurry? I had real trouble getting it into focus. The only way I could find was to use the digital zoom in Sharpcap to get it as sharp as possible, as big as possible. However, it still looks quite fuzzy  and indistinct to me. Is it my 5x Barlow not being up to the job? It's the first time I used it and it's not a cheapo thing - a Bresser, about 50 quid, seems fairly good. Perhaps it just isn't suited to the rest of my setup, and I should continue with the 3x instead?

* Should I just accept that my setup isn't optimised for planetary? I usually do DSOs but as I say, I thought I'd give Saturn and Jupiter a blast with the T7C (which is usually my guide scope). Having said which, I've seen examples using a 130PDS and an ASI120MC (which the T7C is, effectively) that are much better.

Any/all feedback please?

Thanks, Brendan

A Goto EQ mount is pretty much essential for decent DSO astrophotography. You can do some work with an AZ mount but, from experience, having tried DSO astro with an AZ, I can tell you that EQ is the way to go.

It seems some people can't get enough backfocus with their DSLR and a 200P, but you seem able to, so that's a good start. I notice you refer to the 130P - be careful, if you mean 130PDS then that's ok (the 'DS' bit refers to the Dual Speed focus), but the 130P really doesn't have enough backfocus for prime focus with a DSLR. Believe me, I know: it's the reason I sold mine and got a 130PDS instead!

I would say that an EQ3 might not be stable enough for a 200P however. With astrophotography, it's almost totally the other way around from observing. Instead of a big aperture on an AZ mount, you need a smaller scope on a solid EQ mount, so everything is stable. This includes being able to withstand low breezes etc. So, I have my 130PDS on an NEQ6 mount which is most definitely overkill, but a 130PDS on an EQ3 mount would probably be ok. I wonder whether a big 200P might not be stable, and could suffer in light winds.

The 130PDS is also good because you can use it for both imaging and observing. 

So, if there's a good offer at FLO, you could either get that package and sell the 200P to go towards it, or keep it if you want to swap it out when observing, or you could even see how the EQ3 handles the 200P and if it works out, sell the 130PDS!

It was a real pain. I initially thought it would make sense to stitch the unstretched panels, then post-process them in StarTools. I planned to do this in Microsoft ICE, until I found out it had disappeared! I found a copy online, but then it either wouldn't recognise the overlaps, or if it did, I couldn't control which bits of which panel to use. In the end I found it was best to process the panels first, then stitch them together, using Affinity Photo. It has a nice panorama feature that allows control over masking, so I could tell it which bits of which panel I wanted 'on top' as it were, then it did a good job of colour-balancing everything and rendering it. So, now I know, but I wish I'd known before trying, over and over again, using different stacking algorithms, different software, different orders of doing things, starting again, trying again, etc etc etc. Basically there are 999,999,999,999 ways of doing this wrong, and I found all of them. On the 1,000,000,000,000th attempt, I got it right.

Hi all

Finally finished this one - a four-pane mosaic going from the North America Nebula across to the Pelican Nebula. Culmination of the eight clear nights we had during July in the UK, and literally hours and hours of trying to get it to work. I've never done a mosaic of a nebula before and it was a very steep learning curve (yes, another one).

* 17:39 hours of integration at ISO800 from 120x120s + 37x180s + 177x240s subs, over 8 nights (had to use different exposure times to cope with light pollution and varying Moon phases)
* Bortle 4 sky, Moon average 60% phase, 27° height
* Calibration: 25 flats, 25 dark flats, 50 darks
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount, Canon EOS1000D DSLR camera with IR filter removed, Sky-Watcher 0.9x coma corrector, Datyson T7C guide camera, Angel Eyes 50mm guide scope
* Software: Polar alignment with SharpCap Pro, guiding with PHD2, capture with Astrophotography Tool (APT), stacking with Deep Sky Stacker (DSS), post-processing with StarTools, Photoshop CS2, Affinity Photo and Topaz Denoise AI

Cheers, Brendan

Excellent answers! Thank you so much. I did look for a 130PDS manual but obviously there's nothing. Didn't occur to me to look at their Quattro range.

Hi all,

I've just realised how to correct something that's been bugging me for a while - I have a small amount of tilt on my focuser tube. I can see it when using my Cheshire, and fix it by inserting a sheet of paper on one side between the Cheshire and the drawtube.

So my question is: how do I correct this? I've heard tell that 'the grub screws at the base of the focuser' are for this, but then that raises two more questions: there are some at the base of the focuser, and some on the part of the focuser attached to the tube, so which grubs do this (A or B in the photo)?

And if it's the ones on the base, then given that at least one of them is totally obscured by the focuser knob, how on earth would I access it (arrow and question mark)?

Thanks, Brendan

Thank you.

Hi all,

I fitted one of these recently. It's a baffle, for hiding the primary mirror clips and hopefully improving the clarity of my stars. 

However, on testing it by taking shots before and after of Vega, I'm underwhelmed.

Also, in my latest shot of M11, there's clearly something wrong with the two stars to the right (the blue and yellow one - the only ones bright enough to display diffraction spikes). They seem to be bleeding/bloating out bottom right.

Here they are unstretched - odd shapes.

So, have I overtightened the screws on the primary mirror when fitting the baffle? They were pretty tight to begin with (never removed them before). I've since loosened them by checking a card fits under them as per this video: https://www.youtube.com/watch?v=EOFYyhkwG_Y

However, given that even a half decent night is quite some way away for checking whether this is fixed, could anyone who knows about this sort of thing give me their take on what's going on here?

Thanks, Brendan

Thank you! Of course you can - it's great to think it's being used in this way.

Finally finished this - a four-pane mosaic going from the North America Nebula across to the Pelican Nebula. Culmination of the past 8 clear nights, and literally hours and hours of trying to  get it to work. I've never done a mosaic of a nebula before and it was a very steep learning curve (yes, another one).
* 17:39 hours of integration at ISO800 from 120x120s + 37x180s + 177x240s subs, over 8 nights
* Bortle 4 sky, Moon average 60% phase, 27° height
* Calibration: 25 flats, 25 dark flats, 50 darks
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount, Canon EOS1000D DSLR camera with IR filter removed, Sky-Watcher 0.9x coma corrector, Datyson T7C guide camera, Angel Eyes 50mm guide scope
* Software: Polar alignment with SharpCap Pro, guiding with PHD2, capture with Astrophotography Tool (APT), stacking with Deep Sky Stacker (DSS), post-processing with StarTools, Photoshop CS2, Affinity Photo and Topaz Denoise AI

Affinity Photo's panorama feature did the trick in the end. 

Just to tie this one off, I discovered that Affinity Pro has a great panorama feature and that did the job nicely - much more control over which bits of which images to include.

So, finally finished - a four-pane mosaic going from the North America Nebula across to the Pelican Nebula. Culmination of the past 8 clear nights, and literally hours and hours of trying to  get it to work. I've never done a mosaic of a nebula before and it was a very steep learning curve (yes, another one).

* 17:39 hours of integration at ISO800 from 120x120s + 37x180s + 177x240s subs, over 8 nights
* Bortle 4 sky, Moon average 60% phase, 27° height
* Calibration: 25 flats, 25 dark flats, 50 darks
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount, Canon EOS1000D DSLR camera with IR filter removed, Sky-Watcher 0.9x coma corrector, Datyson T7C guide camera, Angel Eyes 50mm guide scope
* Software: Polar alignment with SharpCap Pro, guiding with PHD2, capture with Astrophotography Tool (APT), stacking with Deep Sky Stacker (DSS), post-processing with StarTools, Photoshop CS2, Affinity Photo and Topaz Denoise AI, mangling with Facebook

Hmmm, just realised I can copy all the files into a separate folder (for safety!), drag and drop them into the Main Group of a DSS session, then order the lot by their score. Then, figure out what 40% of the total number of subs would be, and remove them. It's a workaround I guess.

Hi all,

I have a fairly complex DSS job, made up of over 20 groups.

I've decided the image I like best is when stacking the top 60%. Which means that, when all this is done, I won't be needing the other 40% of subs.

So my question is: how can I quickly/easily determine which of the subs to lose?

The only way I can see is to make a note of the quality score for each sub - across all the groups - put them into a spreadsheet, and calculate the top 60%. This will take ages ie not quick.

I've looked in the .txt info files and the information's in there too, so in theory I could write a macro or something to pull it from them. But again, quite complex ie not easy.

Any ideas?

Thanks, Brendan