rickwayne

Wowsers. Great image. ABSURDLY great image for your first NB!

Something wrong there but I can't tease it out -- an object will move faster across the sensor when it's nearer the celestial equator. If you think about it, a star near Polaris might stay on the sensor all night.

There are FOV calculators online (e.g. astronomy.tools FOV calculator for eyepieces and CCD calculators) but I'm not sure how to set up for eyepiece projection.

7 hours ago, -Joe_ said:

Like Rick, I just use it on my mac. Comes as a download for kstars - everything included. Worked without any fiddling. There’s a link on the indilib downloads section. 

Got a raspi4 recently and going to have a play with that and see if I prefer it on a pi or just the laptop. I’m only in the backyard and it’s summer at the moment so no real need for a remote rig. That might change once it’s cold though ;o) and I also want to plan for getting the setup mobile so I can go out to darker skies and better views.

As you probably know there's an active effort going to port stuff to the 4. Back when I was first acquiring this stuff there were some solid reasons to use Ubuntu over Raspian, but maybe you could use the OS that come with the 4 and install packages now? It's so new that I'll actually be surprised if that works, but please keep us posted. Mmmm, USB3 and enough CPU to plate-solve conveniently...

12 hours ago, Starwiz said:

It looks very nice.  I guess the downside is the additional cost.

I suppose if you bought an ASiAir or a StellarMate gadget, there would be a cost, sure. Cheaper to buy your own Pi for $35, pick up a case for a couple dollars, get a microSD card for under $10, and get all the StellarMate software as a download for $49.

But if you don't need the battery-miser Pi, you could simply download and run KStars and Ekos on your laptop, for $0. It's all open-source, and the INDI community support is there whether or not you paid Jasem for StellarMate OS or the Gadget. It's exactly the same stuff. I run it on my Mac as an alternative to the Pi.

I would not wish to dissuade you from your software choices, but you might try KStars/Ekos. When you start the INDI server that talks to the devices, you will see right away whether or not the connections have been made properly. The guiding and capture modules both have camera-chooser widgets, so you can specify your 120 for the guider and 1600 for capture easily enough. In fact you can switch them if you want to test something. You get special bragging rights if you're imaging with a 120 and guiding with a 1600, you know.

Nice! I've tried that region in Ha but now you've got me wanting to point an OIII at it too.

Star color much there? :-0

Bravo!

You know, I just posted a smiley in another thread about getting banned if I plugged Ekos one more time...but hey, it'll do mosaics in addition to everything else.

Will I be banned if I plug Ekos yet again? 🙂

I started out with Sara Wager's very basic introductory videos. And, in fact, that's all I've needed so far. I haven't explored the settings much, since I've been remarkably content with the results from the "happy path" of default settings. I know Mabula just posted that they're working on simplifying the registration process, which I thought was pretty much "click and go" but what do I know. I actually wouldn't mind a discussion of the various settings on the "integration" tab and when you might want to use them, as well as more on the various image sliders in the right pane. Really I don't think the latter lack for explication, I just haven't internalized it yet.

I would recommend picking up a copy of Charles Bracken's The Deep-Sky Imaging Primer. In addition to a wealth of information that really helps bring your imaging up to snuff, he has a great list of targets in the back of the book grouped by size. Best forty bucks I've spent in astrophotography.

On 25/06/2019 at 12:40, PhotoGav said:

Thank you. Yes, processing is quite possibly the larger half of the story! I am a big fan of Astro Pixel Processor - it does all the donkey work, preparing everything ready for a lot less tweaking in PhotoShop than I used to do.

I'm only a month into my affair with APP but it's pretty torrid, let me tell you. Quite a lovely image, and your questions make it astronomy as well as art.

I think very few people are still using webcams for astro, hence the lack of response. Even for autoguiding, it may not be cheaper as such to buy a dedicated astro camera but it rapidly evens out if you don't have unlimited spare time. I know that $150 can still be a lot of money; ASI120s can be had on the Cloudy Nights classifieds for $100 or less.

"Something came out" is often a triumph for me! Plenty to like here.

Ooo, we're 183 Buddies! Although you've got total snobbery rights with a Baader Ha filter there, instead of my measly ZWO.

I hope you just enjoy the heck out of the thing. I really like the smaller pixels that let me crop more aggressively without making my images look like Minecraft screenshots.

Oh. My. Your maturity and restraint serve as a model to us all. EBay, nothing, I would have been more like "It's all going ON THE MOON" and started hurling things.

I can't say I haven't had KStars and Ekos roll over and die on me. But at least on the Mac it's uncommon. On the Pi...maybe once every other imaging session. If I'm checking it, no huhu, I just miss a bit of imaging time till I get it back up. If not...lunar astronomy. I am saying.

21 hours ago, carastro said:

Not sure where you formed that impression, but I don't/can't use Photoshop for registering. 

Oh, sorry Carole! I just formed an assumption based on your text and the screen shot. Never mind!

Siril is definitely worth a look. It has its quirks, and has misbehaved occasionally for me and for some friends, but it's my go-to among the free programs for stacking. Multiplatform, open source, reasonably performant. User interface takes a bit of getting used to and it does leave intermediate files on your disk with the gay abandon of a bunny fertilizing your yard. Calibration, registration, stacking, and (L)RGB composition are pretty straightforward (in addition to the registration it does among the subs in a stack, it also automatically registers your L, R, G, and B frames.)

Demosaicing Bayer-gridded frames is a bit nonobvious, easy enough once you get it.

Wow, is that a ringing endorsement or what?

And if you want a simpler life you can go with so-called "bicolor" imaging, with just the two brightest wavelengths (for emission nebulae, H-alpha and O-III). Some folks create a synthetic green channel by mixing the H-alpha and O-III, some just let its bicolor freak flag fly.

There is an excellent reference on Cloudy Nights on initial settings for the ASI 183: https://www.cloudynights.com/topic/616524-sub-exposure-tables-for-the-zwo-asi183mm-and-qhy183m-and-colour-versions/. If you're running with just a light-pollution filter, use the "Broadband" category. Don't sweat the sky-brightness criteria too much, you'll probably wind up changing from that initial exposure anyway. This is just a recommended starting point.

Oh, and flats: Unless you're some sort of luck genius, the filter sitting so close to the imaging sensor is just a haven for little dust motes. I never appreciated the ultrasonic cleaning feature of my DSLR so much until I had to live without it. The point about sensor proximity is that the shadows' circles of confusion are actually small enough to be visible when you stretch the image (unlike those of dust on the objective lens). You won't see it in an unstretched sub-exposure, but my stretched subs often look as if my imaging train has come down with measles.

So you want to shoot flats. Calibrates right out. 🙂

PS: Speaking of registering R/G/B  or H-a/O-III/whatever: Siril also does a pretty decent job there. I'm super-impressed that carastro can get Photoshop to work for that, in my experience it sucks at that task. Seriously, I will never even bother trying PS for that purpose ever again. Astro Pixel Processor is absolutely outstanding.

I don't think you'll be sorry. The 183 demands a slightly higher game than, say, the 1600, but I can't say enough good things about mine. You probably always already process with darks, but you will never process again without them, tell you that for free -- the amp glow on the thing is pretty stark. When you look at your first light and scream "AAAAA, WHO'S SHINING FLASHLIGHTS ON THE SIDE OF MY SENSOR?!!" just breathe and repeat The 183 Mantra:

  It calibrates out.

  It calibrates out.

  It calibrates out.

But you certainly do want darks at exactly that gain, temp, and exposure!

Well, that is annoying. Normally "they" say don't bother binning your main camera unless it's a CCD, it just cuts down the number of pixels without any improvement to signal/noise. But here cutting down the pixel count is exactly what we want!

Downsampling should produce a similar result, but offloading the binning to the camera (if that worked) would necessitate less CPU time downsampling, in addition to speeding up the image download.

That's a pretty annoying hit.

Note that the 183 comes with a filter holder -- at least mine did! -- that threads into the interior of the adapter rings, so that you can mount a 1.25" filter without going out and buying anything else. I didn't think I'd be very happy with black and white imaging but I've been pretty happy with some of the stuff I've been able to pull off in my (red zone) back yard with a 183MM and the ZWO Ha filter. (Yes, it's RIck's Horse again. What can I say, it's my favorite image so far. 🙂 ) 

 

I find that platesolving works quite well for my guide camera on the Pi, not so much for the main (20 MP) one. I have had it work, mind, but it's slow and doesn't always solve. Five things:

1. In some cases the lack of index files will only slow solving, rather than kill it, as the software has to search for its image within larger footprints rather than find it quickly within smaller ones.
2. Do ensure that the astrometry index files are actually in the correct place.
3. Try selecting your guide camera and solving with that. The smaller image should make it more palatable to the Pi, and will serve as a smoke-test. Depending on how well your guide and main scopes are collimated, it might even be all you really, truly need.
4. Check the command-line parameters that Ekos is passing to astrometry. In mine, I have it downsampling 16x.
5. Are you seeing reasonably focused stars in the images it's trying to solve? Poor focus can make it spin endlessly (go on, ask me how I know...)

I have to say that, having tried it with the Pi and with a 2018 Retina MacBook Pro, one of those things is a lot less frustrating than the other. But one of them will run all night on about seven electrons, and the other gives me maybe two hours of imaging and it's Tango Uniform Mode Time.

Re sub length: IIRC Sara is doing her (absolutely gorgeous, I go to your site every time my Envy Level drops and I need a refresh) imaging from very dark skies, so her narrowband subs will be much longer than we wee mortals'. ?

Y'know, sensor size is not in itself an advantage. You want to match your desired FOV to the sensor size, yes, but angular pixel size is also in play. I deliberately chose a smaller sensor for my first dedicated astro camera precisely so that smaller objects would more nearly fill the frame, while the smaller pixels helped address the undersampling that my DSLR rig gives me. Smaller-pixel sensors are often noisier than bigger-pixel ones, true, but between today's sensors and stacking, that's a lot less of a problem than it used to be.