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Just thinking out loud about how to capture the upcoming lunar eclipse on March 13/14 with a somewhat recently purchased ASI2600MC. The majority of my AP experience is with Deep Sky, but now have the the opportunity to use the 2600MC on an Esprit 100ED from a remote location. From an Astrobin search, DSLR cameras seem to be a favorite for this type of event but need to use the gear already in place. The moon should be framed nicely with this cam and scope combination but am looking for someone who can comment on OSC capture technique. So perhaps bracket some exposures lengths and go for longer subs during totality? Already using NINA but would might consider other apps as well. There should be some time to practice on the waxing gibbous moon in the days leading up. If anyone can advise or point to some good documentation on best practices I'd appreciate it. Would like to be somewhat prepared for doing this lunar event ahead of time  . Sure the moon is a common target, but just not for me with this gear.Thanks, John |
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The apparent motion of the Moon is around 0.5 arcsec per second so you would want to keep that in mind and compare it to your image scale. As a rule of thumb you'd want the duration of your shot not to be more that double the amount to cause differential motion between the Moon and the background stars by more than two pixels. At your native image scale there should be plenty of time. Depending on how dark the eclipse will be you'd want to expose to fill 80% of your dynamic range and no filters if you use an OSC camera. Keep on shooting from start to end of the totality.
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I tried my 2600 with a previous lunar eclipse here. 1. Set your mount tracking rate to lunar, not sidereal, this will stop the drift in RA. 2. Use a fast laptop with SSD to minimise the frame-to-frame delays storing each image. ASaiAir is too slow. 3. Over the duration of the eclipse it will drift a little so consider how to make a guide to re-centre when needed eg apps like SharpCap or ASIStudio that provide a crosshair or target. Or place markers directly on the laptop screen post it-notes or tape, your call) 4. Stability of your rig. The 2600 does not use a global shutter - the pixels are read as sequentially a raster. If you watch it in live view you’ll notice a “jello” effect occurs in response to slight movements in your rig - a passing vehicle, wind etc. 5. Exposure. Strongly suggest you get it out and practice on a full moon first because you might be disappointed, and have another choice as a backup plan eg a DSLR. |
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I've been mentally preparing for this event, which I plan to shoot with my 2400MC and EdgeHD 9.25. Definitely must set the mount to lunar rather than sidereal as noted by @MaksPower . I have taken some moon images in the past, and I went with the video capture method, in 16-bit SER video format, then using Autostakkert! to process perhaps 500-1000 of the best frames within each 1-2 minute video. On a fully illuminated moon, my frames were a nice, manageable 40ms or so. My final image is: https://www.astrobin.com/2y5eqq/ My concern will be the much dimmer illumination of the moon during totality. I am not sure whether i can shoot video at an exposure that will likely be on the order of 1". I still need to research if that is possible. If not, then I'll have to shoot a bunch of stills and stack them like DSOs. Important note if you are an Asiair user. If you go the video route - don't use the ASIAir with the camera. Asiair does not handle video beyond HD (1920 x 1200), so if you use it, you'll only get a small rectangle of the 6000x4000 resolution of your 2600MC. Here is what ASIAir gave me on my 2400MC at 6kx4k setting - even though the full disc of the moon was in my full-sensor preview screen:  That would be a disappointing result for this event. Here is my plan, assuming I can go the video route:
This general recipe is what I can do without expanding software. So I'll be awake and scopeside during the night... taking occasional test exposures between video runs and adjusting exposures. But due to the variable nature of a lunar eclipse, there's no knowing the best exposure so it will be trial and error with live corrections. As you mentioned in your subject post, @JohnAdastra , I'd also be interested in other takes on this subject! CS, Mark |
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I too was primarily a deep sky guy until I bought an EdgeHD 8" and decided to dabble in planetary. You treat the moon like you would a planet. Even at it's thinnest crescent and even during the total eclipse it's going to be enormously bright. So with astro-cams, it's usually easier treat it like a planet and take video. Use Sharpcap or Firecapture to get the video, then autostakkert to produce a single stacked image, then process the image in any number of ways from Pixinsight to Photoshop. There's a dozen different youtube guides on Sharpcap and firecapture. I just uploaded a bunch of pics to my gallery of the Moon I took with my 2600MC Pro throughout last December. I was planning on doing the same for the eclipse, using short videos then stacking them later... Adjusting settings to get proper exposure shouldn't be too difficult in Sharpcap as the eclipse is progressing, depending on how often I want to take pics for a time lapse... The 2600 isn't known for it's high frame rate, even cropping down a bit, using my EdgeHD 8" and a reducer, I think it'll be less than 20FPS, so doing a 1000 frame video is probably not a good idea. Then take into account that the shadow will be moving, I'd say keep it to ~100 frames or so per exposure.... Maybe someone with more experience could give more specific advice. @Mark Fox had some great advice for ASIAir users, I used nearly that exact method because I'm too lazy to learn NINA just yet. OP you'll have it a bit easier. I don't know what video options NINA has, but I'd recommend SharpCap Pro (I think it's worth the $30), but FireCapture is very good as well, and it's free. They both offer very direct control of the 2600 and easy on-the-fly adjustments. |
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Also note the diameter of the lunar image is close to 10mm per 1000mm focal length, so choose your scope accordingly.
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Another +1 for short exposures, especially video. Even though you set the RA tracking to lunar, there will still be appreciable DEC drift due to moon's tilted orbital motion, maybe an order of magnitude less than RA, but not negligible... probably a couple of arcsec per minute. On the 2400MC with 3.8um pixels (approx), that's definitely a few pixels drift fairly quickly for those of us thinking video capture. Going through this exercise has been helpful, and I recall my experience with my moon shots has been that I didn't care about tracking sidereal vs lunar, nor with any DEC drift. Autostakkert! automatically took care of the drifting between frames. I have shot as much as 9 minutes in a single video, and at the RA drift figure courtesy of @andrea tasselli , i would have seen a drift of 540 sec (9 min) exp x 0.5 arcsec / sec = 4.5 arcMIN over my exposure. On my fatpixel 2400MC, that would have been a drift of over 500 pixels. No problem for Autostakkert! . The key will be shortest possible subframe exposures. No doubt about that. I may consider going with some combo of a darker histogram, 0.7x reducer, and stretching in processing. I dunno....I'll figure it out and if I totally blow it, I always have March 3, 2026 in my back pocket. And will likely dwell on my failure for a year. |
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Thanks everyone for their replies. The Esprit 100 is mounted on top of a GSO 16" RC and uses a Paramount ME mount. Tracking is very good even without guiding, though lunar rate has not been tried yet. The moon is framed nicely but won't tolerate much drift as the margins are not overly large. Video capture is something else not tried so I'm wondering how much storage that would consume on the mini PC. Downloads are usually pretty quick through a Pegasus Power Box v3 but video mode would need to be tested. I was hoping for some automated exposures as the end of the event will be in the wee hours (~5AM?) and I probably won't last that long. The partial phases I might be able to anticipate with exposures of the gibbous moon in the days before, the dim reddish totality phase will need to be trial and error during the event. During special events like this is when you regret not doing lunar on a regular basis to gain the experiences. Moving forward. Hope to hear more on this thread .CS, John |
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Video capture is something else not tried so I'm wondering how much storage that would consume on the mini PC Unfortunately, it will take quite a bit. Video in this case is just the FPS of single images... So without cropping each picture is about 50 megabytes, if you take 100 frames of video that's about 5 gigs each... I have a 4tb external hard drive... I was planning 100 frames every 5 minutes over the ~4 hours of the eclipse, so that's what... 200gb? Hmm... maybe I should go every 2 minutes... |
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It will be a lot. Unfortunately I haven't tried video from the ASI2600MC but I did with the ASI533 - and I measured a sustained 9GB per minute at its max frame rate for the full 9 megapixels, using ASIStudio. Not sure whether the limit was USB3, the CPU or the SSD storage. Using stills from the ASI2600 at 100/minute: 53MB x 100 frames/min x say 120 minutes = 636 GB The snag is, at 100 frames/minute = 5.3GB/minute which will tax a lot of PC's; they keep up for a bit by buffering in RAM, then that has to be flushed to disk and they freeze for a few seconds while that happens. Try it and see what I mean. |
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Yes. Thanks guys. There is a 2TB on the mini PC, which amazingly has started to reach capacity not including image files. There is also another 4TB SSD drive connected by USB 3.0 which has the capacity but also seems to fail at temperatures approaching freezing or lower. I've yet to find any external drive that's rated for low temperature to sub in either. But trying to see how things will function will only be achieved by a test run as you stated. I don't think I need to video the entire eclipse, just run it at various stages and which I think NINA can do with Smart Exposure. Now the moon is coming up late just before new moon, and there will be time between that and full moon to give all these ideas a test. All tips appreciated. CS, John |
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Strongly suggest you test the performance of the miniPC. Connect the camera to it, power up and see what the sustained frame rate is over several minutes. |
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You don't need all this stuff. Like at all. Ever. 1 shot and you're good to go. OK, let's say 1 shot a minute for the totality phase, that will allow for enough fall back and some limited stacking (to preserve stars).
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andrea tasselli: Thanks Andrea. Simplicity is probably the best approach. |
