BrendanC

So I was able to mitigate the spike(s) fortunately. Still, I need to sort this!

So, I've been through them and as far as I can tell the spikes (yes, you're right, there are two) track the stars exactly. I can even see where they move around a hot pixel, but stay aligned with the stars.

I'm wondering whether Merak could have been the culprit? I think I tested the image by moving away from that side, past the Owl Nebula, which would have been in the wrong direction. I guess I should have done a series of subs around the image to do a better test.

Tonight is another clear night (amazing), so I'm going to have another go. I've actually rotated the camera 180 degrees this time, so I can see any effects from that, while retaining the framing I want. If the spikes appear again, I might try and get some subs from nearer the surfboard side and see what happens.

In the meantime I'm going to process the image by stretching the sky a lot less, and superimpose the objects. It's a bit of a cheat I guess, but DSS won't reject the spikes because they're an intrinsic part of the image.

Good to know it's not a result of the sensor cleaning (which I didn't think it was, but these things always seem to happen whenever you change anything!)

Thanks for the suggestions, really appreciate the help. Let's see what happens tonight...

@tooth_dr Good idea, and it's what I was thinking too, but why wouldn't it appear with the other images I took?

@vlaiv I've looked to see if it moves and it doesn't seem to, but I can look VERY closely, almost pixel-peeking, and I'll let you know. BUT, I would still have expected it to have shifted by 180 degrees post meridian flip?

Hi all,

I need some help figuring this one out!

Imaging the Owl Nebula and Surfboard Galaxy last night, good conditions, no moon, seeing could have been better but everything was fine.

Then the subs started to come through and I noticed a weird spike cutting across them.

I went outside and looked around - no unusual lights anywhere. The only difference was that I'd cleaned the sensor beforehand.

I was also imaging the Sombrero Galaxy, so I waited for those subs to come through - no spikes.

The plan then went back to the Owl Nebula (I planned it so I caught the Sombrero as it appeared behind some trees). This time, it was after the meridian flip, so I figured that if it was the camera, the spike would still be in the same place but the image rotated 180 degrees. Blow me down wiv a fevver - the spike had rotated too! This implies to me it was a genuine artefact in the sky. 

I went out again, this time put the dew shield on and covered the base of the OTA with a hat, just in case any stray light was causing problems. Made no difference. It's a huge spike or trail or line, reminiscent of a satellite trail but really not. I notice that it's aligned with the diffraction spikes, but that's really all I can add. I took other subs, around the area, and some of stars, to see if I could replicate it, but it only seemed to happen in this fairly specific area of the sky.

Is it the 'zodiacal light' I've been reading about recently? Is it a VERY persistent contrail in the sky? Is it aliens?

Here's the stacked image, stretched in StarTools, just to show you it in extreme contrast:

It moves with the dithering, so it's not the camera or sensor.

So, I'm stumped. I'm going to try and lose the streak in pre-processing, but until anyone can give me a reason for this, I'm going to call it BrendanC's Streak.

Equipment was a Sky-Watcher 130PDS on an NEQ6 mount, astro-modded EOS1000D, guided 180s exposures, dithered by my usual value of 12 in APT.

Any ideas?

Thanks, Brendan

Hey, glad it worked!

I never came back to give my opinion of the Concenter...

So, what I found was, that it's good for getting the secondary in the centre, as the name suggests, but not initially for getting it round. This is because my secondary was a bit too far up the tube. That's where the phone method worked for me - I could move the Mire de Collimation circles so that they were over the secondary, and then get it nice and round. Then, I used the Concenter to get it centered.

I suppose I could have done this the other way around ie use the Concenter to get it centered, and then use it again to get it round. However, I also found that, when the secondary was ALMOST centered, I would get 'lost' when following the concentric rings in the Concenter. It was hard to tell whether they were crossing sometimes.

Anyway, the combination definitely did work - Mire de Collimation for roundness, Concenter for centrality and then precise roundness, and now for quick checks. Over the past three months I've used it twice to make sure the secondary is in position, and it's been fine. All I do now before each shoot is quickly check the primary with a Cheshire, and I'm good to go. I guess the cost of the Concenter was something ideally I wouldn't have paid for, but just for the peace of mind knowing it's sorted, it made a big difference.

Hang about though, something's wrong with the invite times.

8PM BST is actually 7PM in London, not 8PM!

Could someone confirm what time this will be please?

Brilliant, definitely will be there.

Just been reliably informed that it's just a known bug in the output message, and the software works as it should. Phew...! 

I've been using DSS for nearly two years now, but occasionally I decide to revisit the basics, just to make sure there's nothing I've forgotten or am doing wrong.

I just noticed something that bothers me.

I just added my flats and my flat darks to the Main Group, so that they're used across all the other groups. Right so far?

Then I added my lights at 10 degrees C, 11C and 12C into Groups 1, 2 and 3, so that they're all processed separately. Then I also added my master darks into those groups - again, the 10C master dark into Group 1, 11C into group 2, and 12C into group 3. Again, so far so good?

Then I decided to play around with the DSS recommendations to see what it suggests (Settings menu, Recommended option)

Scroll down, and it says: 'You are creating a master dark from 3 dark frame(s)'

Whaaaaaaaaat? My understanding for quite some time has been that the master darks go with the lights, in separate groups. That way the correct master dark is used for the relevant lights, whether grouping them by ISO, temperature or exposure. But this message very strongly implies to me that somehow, for some reason, DSS is going to create ONE master dark from the three I've provided, and apply that across ALL the groups. 

This is crazy. Isn't it? 

I'm hoping that this is a badly-worded message, and that DSS really does behave as I understood it to behave...

Any takers?

No reply=no benefits, I guess!

Hi all,

I recently signed up for a free Astrobin account. I have some photos uploaded, not reached the free limit of ten yet. It's been sort of nice to get people liking my images, but apart from that, I can't really see much benefit to using it. Also there are other sites such as Telescopius that host images for free, although the community doesn't seem quite as large.

However, I'm always on the lookout for interesting new things to explore. So, I'm just wondering, on an idle Sunday, whether there are huge benefits to using it that I've overlooked? Anyone use it and really like it? If so, why?

Thanks, Brendan

Do you mind if I recommend two things for backup? I'd consider that as important as the spec!

I've been using OneDrive's 1TB plan for the past year and it's invaluable. It allows me to work on images across machines, and it's really great knowing that it's working in the background to back everything up.

However, given the golden rule of three of backups - ie you should have three copies, in three different formats - I also use a very neat little utility called Bvckup, which you have to pay for, but that also works in the background to copy things to a local drive: see https://bvckup2.com/

I've recovered files from both - quick, easy, and reliable. The other golden rule of data: it has no value unless it's backed up!

Super-quick question: what are the Description.txt files that accompany master files in Deep Sky Stacker? More importantly, do I need to keep them?

The reason I ask is that I have all my individual dark files still stored, and I really don't need them: I just need to keep the master files.

However, I don't know whether I also need to keep the master Description.txt files too.

From what I gather on looking at them, they're just descriptions of the individual dark files that are used to make them. So, I probably don't need to keep them. However, before I do this, can anyone confirm please?

Thanks!

Just took another look and planned the mosaic in Telescopius.

How would this look? Does it include all the essential elements, do you think?

Hi all,

So, given we have a few clear nights coming up but they're going to be full moons or near enough, I've decided this is the ideal time to embark on a project I've wanted to do for a while: a matrix of the Hyades.

However, I'm having difficulty establishing exactly what such a shot should include. I'd ideally like it to include Aldebaran, even though that's not officially part of the cluster. However, every photo I look at seems to include different extents of the sky.

Does anyone know: what should a shot of the Hyades include? And if you could also provide a photo that would be great.

It would just be very disheartening to spend all the time doing this only to realise I've missed a bit!

Thanks, Brendan

Thank you. Pretty much my feelings too. I might stick with clusters, but just give M51 a quick try at low exposures and see if it's worth pursuing. 

Hi all,

Given a rare full clear night, obviously it's going to be a full moon!

I'm considering clusters for photography, but also M51.

If I do M51, would anyone happen to have any recommendations regarding exposure times at ISO800 (which I shoot everything at)? 

This will be with a 130PDS, a modded EOS1000D, on an NEQ6, guided, under Bortle 4 skies.

I mean, I'll be checking the histogram and possibly taking varied exposure times - I expect 120s, 180s and 240s - but if anyone has any recommendations that would be great.

Thanks, Brendan

On 22/02/2021 at 16:55, groberts said:

That looks really good on the wall Brendan, would be interesting to know the imaging details 

Sure, here you go:
• 16.25 hours of integration time, made up of 29x120s, 152x180s and 115x240s - simply because I've just started guiding and am increasing exposure times each session to see what my kit can do, and what works given my skies
• Bortle 4 sky, moon average 49% phase
• Calibration: 25 flats, 25 dark flats, 50 darks
• Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount, Canon EOS1000D astro-modded camera with Sky-Watcher 0.9x coma corrector, T7C guidescope (ASI120MC clone), Angel Eyes 50mm guidescope
• 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

Just thought I'd pop up again and say I didn't give up.

Thanks! So, you think the DSLR approach will work better than the T7C approach?

I agree a mono camera with an IR pass filter would work well, but then, as the saying goes, if I had eggs, and I had ham, I could have ham and eggs!

Hi all,

I've done a fair amount of DSO work, but not much lunar. I'm going to change that tomorrow night hopefully, with some experiments to see what works best with my kit.

I have a 130PDS on an NEQ6 mount, and two cameras: a modded Canon EOS1000D DSLR, and a T7C which is essentially identical to the ZWO ASI120MC, which I usually use for guiding but doubles as a solar system camera. I also have a 3x Barlow and a 5x Barlow.

My capture software is usually APT, but I also have Sharpcap Pro which I usually use for polar alignment, but I've also used it for solar system video capture.

I want to get close and personal so I'll be using the 5x Barlow, and taking lots of shots while manually slewing around the Moon's surface, then bringing them together as a mosaic in Microsoft ICE. I'll also be driving the scope with Stellarium so that it tracks the Moon.

However, I'm not sure about the best use of the other equipment:

• APT with DSLR - I wouldn't be using the Live View settings because they're so low-res, so I'd be wanting to take lots of fast, single shots. Would this work? If so, any recommendations on exposure time if I use ISO800, which is what my darks library is based around?
• APT with T7C - I know that APT takes lots of JPGs rather than recording a video file. Is this a problem? I get the feeling APT is more about DSOs than solar system stuff, but I could be wrong.
• Sharpcap with T7C - seems a more natural combination for this kind of work. But, again, I could be wrong.

(Oh, and Sharpcap with DSLR is excluded because I just use the open source ASCOM drivers with the DSLR and I really don't think I'd get much joy using it for anything else other than polar alignment.)

I'll probably experiment with those three combinations, but does anyone know if any of them are likely to work really well, or work really badly?

Thanks, Brendan

Thanks. The middle is fine, it's mainly the stuff for example top right of the shot, all that nice nebula structure that just seems to fall flat to me, when other shots with similar equipment handle it better. 

A month ago, I got some subs of the Rosette Nebula. There was a ton of light pollution from the Moon, which really bleached out the surrounding nebulosity, although the core was ok. Over the past week I've had another go at this, in perfect conditions - but still, I feel this is lacking something. When I look at other versions on Astrobin, using the same camera (examples here), they seem to capture more of the outlying areas which I thought my camera would do well, being Ha modded. So, does anyone have any recommendations here? Is there a particular module in StarTools that might help (I've had a few stabs at this)? Any cool tweaks in Photoshop or Affinity? Or is this really a case of needing more exposure time to get the outer nebulosity? Perhaps I should just try stacking the Moon-free subs and not try to incorporate everything? Any/all comments appreciated!

Other details:
• 5.8 hours of integration at ISO 800 (29*120s + 152*180s + 87*240s - different times because I'm still finding out how long I can guide for)
• Bortle 4 sky, moon 85% illumination for about half the exposure time, 0% for the other half
• Calibration: 25 flats, 25 dark flats, 50 darks
• Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount, Canon EOS1000D astro-modded camera with Sky-Watcher 0.9x coma corrector, T7C guidescope (ASI120MC clone), Angel Eyes 50mm guidescope
• 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

Thanks all. I'll consult the chaps at the DSS forum.

Right, so, I've been using this method recently and one thing I'm noticing is that it's a right old pain in the Bottom. It works, but it's hard work.

The only files common to all the sessions are the dark flats - in fact, that's just one file, because it's the master.

Everything else - flats, darks and lights - have to be very carefully arranged and copied according to temperature and, in the case of darks, exposure time.

It takes ages and creates a lot of duplication which is always to be avoided for many, many reasons.

For example, I'm trying to bring together three nights' worth of work on the Rosette Nebula. I had to work around some cloud and moon issues, which means I have 60s, 180s and 240s exposures. As a result, right now, I'm stacking them all in a DSS session that comprises 16 groups, with flats and dark flats copied many times throughout. It's a nightmare, and very wasteful on disc space (I know I could remove the duplicated calibration files and just keep the masters but even so...)

So I'm wondering whether, instead of throwing ALL the files into the mix in one go, it's as effective to do them in batches, so I stack for example all my 60 second exposures, then 180 second, then 240 second - and then, in the next step, stack the resulting three images? Rather than stacking absolutely everything in one go?

Before I spend ages confirming this either way, does anyone happen to know? Shout out to @tooth_dr who seems to like answering my questions...!