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Smiller

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Everything posted by Smiller

  1. Sorry for the delayed response but I’ve been away for awhile. Yes, with so many exposures you can do more aggressive sorting to increase the spatial, resolution but the opportunity is limited to brighter objects where yiu can afford to “toss some photons” for the sake of resolution. It really works better for the brightest broadband targets like star clusters, binary stars, and the brightest galaxies and perhaps the cores of a few nebula. M27 is a borderline target in this regard.
  2. My exposure time limit is primarily tracking accuracy and smoothness. Much over 10 seconds and each sub gets a bit unreliable with respect to star quality. The main issues are that a big Dob is very sensitive to the slightest air movement and the tracking motion isn’t silky smooth but tends to wander a few pixels here and there over a 20-30 second timeframe. Field rotation doesn’t kick in until I’m shooting much over 60 degrees to the North or South. Then it can limit me to 8, then 6, and finally 4 seconds. For most targets this never happens. I can reduce field rotation a bit by angling the base of the scope 5-8 degrees North or South depending on target location, but that’s a new concept that I’m testing to ensure it doesn’t degrade scope tracking.
  3. Yes, absolutely it’s total integration time. Even with the Optolong L-Ultimate with its very narrow 3nm/3nm bandpass I’m still sky noise limited at 8 second exposures on the ASI2400MC at f3.7, although just barely with the smaller pixel ASI2600MC at f4.9. The miracle of these low read noise cameras, fast optics, and high QE.
  4. Got a few hours on M27 and tried for a combination of decent details with a larger FOV. So, I shot about 4 hours of data (3000 * 4 second exposures) with my ASI2600MC/Baader Coma corrector (F4.9) for details on the nebula with about 4 hours (1500 * 8 seconds) of exposures with my larger pixel ASI2400MC with my Nexus at F3.7 for a larger field of view (actually cropped to 70% of the frame, so the FOB wasn’t too large) and for more subtle nebulosity details. I have the full FOV along with a crop shown for your convenience. Stats: Telescope: Stock Orion XT12G 12" Goto Alt/Az Dobsonian Camera/Corrector combos: ASI2600MC with Baader Mark III CC (0.52"/pixel) and ASI2400MC with Nexus 0.75xReducer (1.08"/pixel) Capture: ~3000*4 second exposures (ASi2600MC) + ~1500 * 8 second exposures (ASI2400MC) Filter: Optolong L-Ultimate on both Processing: Stacking in SIRIL, processing in APP/PI/Affinity with the Xterminators Sky conditions: Bortle 6/7, Good clarity, little wind, above average seeing, nearly full moon
  5. Thanks for the kind words. I enjoyed doing it and learning over the last year. I will admit that it was fun doing what everyone was telling me was impossible… I kind of felt like an explorer seeing what’s possible and around the next corner. Meanwhile, I continue to improve my technique with it. I need to update the guide as I continue to learn, that’s on my ti do list. A few recent shots with this Dob:
  6. Yes, I gave a presentation on The Astro Imaging Channel on this and it is here:
  7. I processed it as a color image. I did boost the blue channel a tad but didn’t really do any attempt extracting OIII. Since the green channel of my cameras have 15% sensitivity to Ha so if the OIII signal is low it’s very difficult to extract the OIII without doing some fancy extraction based on the specific camera spectral absorption. I haven’t figured out how to do that yet.
  8. I looked at your astrobin and you have a very similar Crescent! Your Oiii filter allowed better Oiii, something I think my setup (dual narrowband) doesn’t do well as a lot of Ha leaks into the G and B channels and I think the software does a poor job of isolating it.
  9. For sure the massive number of subs is a substantial downside. If I could take 3 minute subs or even 30 second subs with my system I would in a heartbeat! I’ve spent many hours testing the various stacking programs (and testing various parameters) to find the ones that have the best combination of speed and quality. Thank goodness for SIRIL for its incredible speed, very high quality output, and the option for using RICE near lossless compression for the 32-bit intermediate results. That combination is incredible. Astro Pixel Processor is much slower but very high quality especially if I need to protect dim nebulosity near the edge of the rotated field with its “multiband blending” feature which is unmatched. DSS didn’t have quite the quality or robustness for me and PI was just too darn slow… way slow! And PI’s output in my testing was nearly identical in quality to APP and SIRIL. How fast is SIRIL? I stacked the veil with SIRIL in 1 hour and 40 minutes. For me that’s not really a problem. With APP, it would take about 8 hours and with PI, it probably wouldn’t ever complete (I often have PI’s WBPP crash), but if it did it would be 16-24 hours or so. If the world of AP only had PI, I wouldn’t be doing this. This is on my 2 year old 8 core laptop… the latest desktops are 2.5-3x faster BTW. For data storage, yeah, I have an internal 2TB SSD for active projects and two external 12TB disks to hold completed projects, one as a backup of the other. With lossless 7z compression in fast mode (which is really quite fast) I can compress 2:1 and 12TB is enough for about 300 projects. That will be years of projects at my rate.
  10. For my second test, I caught the Crescent Nebula with about 4 hours of 8 second exposures. I’m limited to about 8 seconds since I’m just using my unguideD Alt/Az Goto Dobsonian sitting on a piece of plywood on the lawn. This filter is a keeper, even with my super short exposures. Capture stats: Stats: Scope: Orion XT12G 12" Alt/Az Goto Dob with Nexus 0.75x Reducer/Corrector (1125mm/f3.7) Camera: ASI2400MC Filter: Optolong L-Ultimate Capture Stats: about 1723 * 8 second exposures (about 4 hours of exposures over a 5 hour imaging window). Software: Astro Pixel Processor + Affinity Photo + Xterminators Sky conditions: Bortle 6/7, partial moon
  11. Since I shoot very short exposures with my basic Alt/Az Goto Dob, I wasn’t sure I’d see a big advantage with the Optolong-L Ultimate over my less aggressive IDAS NBZ. But my first outing capturing about 3.5 hours of the Veil was a good sign that it’ll be a great addition. Amazing using 6 second exposures with a 3nm bandpass filter. Stats: Scope: Orion XT12G 12" Alt/Az Goto Dob with Nexus 0.75x Reducer/Corrector (1125mm/f3.7) Camera: ASI2400MC Filter: Optolong L-Ultimate Capture Stats: about 1800 * 6 second exposures (3 hours of exposures captured over about 3.5 hours) Software: SIRIL + Affinity Photo + Xterminators Sky conditions: Bortle 6/7, partial moon
  12. Not bad for a first attempt…. 😉 JK. Fantastic image, one I can only dream about getting!
  13. I’ll have to reprocess my images focusing on that galaxy to see if I can extract a tad more resolution from it. The owl nebula as my main target at the time… lol. Also I’ll image again in the future when the supernova cools down for my “before and after” compare.
  14. Awesome! I happened to be imaging that and the owl nebula on the 16th with my 12” Alt/Az Goto Dobsonian, did I happen to get it?
  15. Got another clear night, second one in a week. Decided to spend it on the Owl Nebula and I tried to frame it to sweep up that Surfboard Galaxy too. About 3 hours of 4 second exposures using my Goto 12" Dobsonian (Orion XT12G) and the ASi2400MC camera. Bortle 6/7 skies. Normally I try for 8 second exposures but tracking wasn’t so good so I just cut it back knowing stacking would take longer. No filters. I had trouble rescuing most of the data from doing a dumb thing: I had my radiating heater hanging on a ladder to keep dew and frost away, and the scope eventually slewed enough for the heater to shine into the front of the scope dew shield creating a big orange circle in the middle of about 2/3rds of the lights. Careful background removal was needed to resuscitate the data. Cheers, Steven
  16. Great tips, I’ll have to play with some of these techniques.
  17. Yes, SIRIL is indeed much faster. In fact, I recently did a “chili cook off” between Deep Sky Stacker, SIRIL, PixInsight, and Astro Pixel Processor, all of which I have and have used. DSS and SIRIL were a full 10x faster than APP, and 15x faster than PI. Now SIRIL, APP, and PI all have huge intermediate disk requirements that are 5-15x larger than the original data size (For SIRIL this is especially true if you use the new “-framing=max” setting in 1.2beta that increase the frame size to accommodate my rotating subs). So that is often the limit. Only DSS doesn’t. Did you notice that on your big 3000 sub job you put through SIRIL? Is there a way to avoid that? So why did I stick with APP? Well, as it turns out for some types of jobs, APP has the highest quality results, especially for my system that has a lot of field rotation. APP does a superb job blending the rotated frames. SIRIL and PI do good, but a bit less so, and DSS not so good. SIRIL and DSS do have the highest real time disk speed requirements though. So you do need to have your data on a fast SSD to get that speed. So in this case, in hindsight, I should have probably used SIRIL. My field rotation on this task wasn’t too bad and so I didn’t really need APP’s features. One last thing I need from SIRIL that I haven’t spent the time to figure out is how to align the color planes when I have atmospheric dispersion in my color captures. The align plane feature doesn’t work for me and I’ve asked around for help, but to no avail… I’ve tried several suggestions to no affect. Perhaps you know the solution. I was using the 1.2beta version of SIRIL.
  18. It’s been an especially cloudy Winter in the already cloudy Pacific NW, only 5 clear nights in 4 months…. So after 6 weeks of twiddling my thumbs, I had one clear night between storms. So I ”dolly’ed” my Orion Goto 12” Dobsonian (Orion XT12G) out onto the lawn and pointed it to the Leo Triplet. Seeing was predicted to be horrible given the Jetstream screams overhead in the winter, but it was actually OK, so I got greedy and took shorter than normal exposures hoping for some details on those pesky little galaxies: 3300 (he’s, three thousand three hundred) 4 second exposures from my Bortle 7 skies…. took a full day to stack in APP. Here’s the results of initial post processing: I also like the little galaxy smudges that show up… like little easter eggs.
  19. Good effort. Getting a lot of details in a faint object is so hard. You’re fighting several beasts at the same time: seeing, tracking, and signal to noise. Certainly more detail than I’ve ever captured in that target.
  20. A few people have asked how I do it and I was always typing these long replies. So I decided to write it down and it’s in this document on how I learned to do Deep Sky with my Dob: https://drive.google.com/file/d/1IrL9-wdy6783PtPPElcP5u4r0IP6PbxA/view Cheers, Steven
  21. Well, it is a reasonably fast computer (An ASUS ROG gaming laptop with the 8 core Ryzen 5900HX, 64 Gigs RAM, and a 2 TB NVMe SSD). But patience is the main element: Get it stacking in the morning and come back later in the day when it’s done. So stacking time, storage space, and data management are the big challenges to what I’m doing. But I see the latest laptops using the latest processors are 16 core with twice the speed, storage, etc…. So Moore’s law isn’t quite dead yet and this will get easier over time. Plus I’m using a slow stacking program (Astro Pixel Processor), SIRIL and Deep Sky Stacker are both about 10x faster. I use APP is I’m used to it, like its features, and don’t care so much that it takes the computer time… I just let it do it’s thing.
  22. Oops, slow on the responses, sorry. Yes, I bought the Dob for visual use and it was great for that, but then starting doing planetary and lunar with a planetary camera, then I tried my daughter’s full frame Nikon Z6 in it and took a quick shot of Orion nebula. Then I pointed my planetary camera to M 51 and pretty soon I realized you could do deep sky too… the big breakthroughs were these modern low read noise cameras, fast computers, and using Nina to control everything.
  23. Yes, that is a new appendix I’m adding to try to address some of these other Goto Alt/Az systems. I’m working with folks that have got them to work to see how they’ve done it to provide a few pointers, but it’s still early and I’m not sure what all is possible at this time. I do know this: People have used both the Wifi connection and a USB-to-Serial cable to connect physically to the scope and have used programs like sharpcap and Stellarium through ASCOM drivers. I use NINA and NINA has a “Celestron Alt/Az” ASCOM driver I use but I’m unfamiliar with what drivers and settings these folks are using. Celestron is owned by the same company that makes the Synscan systems so they are the same. There is a current and very active tread on “cloudynights.com” in the Electronic Assisted Astronomy on using the Virtuoso for EAA. That would be a great place to reach out to folks that are doing what you are attempting to do.
  24. Thanks for the kind words and, yes, I guess it did turn into a book. I kept wanting to capture every question asked and get it down in writing and pretty soon it’s 125 pages! I guess it does show the general nature of the complexity. With respect to field rotation, it’s an interesting factor. Clearly short exposures freezes the rotation for each sub well enough, but the good news is the more capable stacking programs can easily stack all the rotated frames into a much larger frame and blend the edges well so it’s just a larger image… a bit of an “auto-mosaic” if you will. Some cropping is required of course. I cover that in the guide also.
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