cucubits Posted February 2, 2022 Share Posted February 2, 2022 Since this came up in the hobbies thread, let's go into a bit more details here. Maybe there are others interested as well or just curious about what can be done with the current amateur technology. I'll do my best not to ramble on too long and I'll post pictures too. Intro: While I've been interested in this topic for a long time, I got somewhat more serious (as many others) at the beginning of the pandemic with Comet Neowise. I started devouring youtube videos, joined an astronomy forum and I fell head first into the rabbit hole. I couldn't stop reading and learning about this and it was completely mindblowing to me how much hidden detail can be extracted from even the most light polluted cities. There are many directions one can take in this hobby: - visual astronomy: sort of old school IMO, where you have eye pieces and just look through a telescope. This is not really doable unless under some really dark skies. From the city, everything is washed out and very hard to see even on the bigger telescopes. - astrophotography: this is my chosen path. It's incredible how much detail can be squeezed out by imaging for crazy long times. Essentially you expose the same spot of the sky for many hours by taking lots and lots of "sub-exposures" which are then combined in software, the noise is more or less discarded and only real signal is left. Deep sky objects like Nebulae, Galaxies, Clusters, Planetary Nebulae (supernova remnants) can be seen with great detail. Over many hours of exposure, you're essentially fishing for real data signal and even the faintest and rarest photons slowly add up and build the image. Gear: Gear is important but not critical at first. With the correct techniques, even a regular camera on a tripod can get unexpected results. On the other end of the mentioned rabbit hole, there's the more expensive telescopes with extremely precise glass, a mount which counters the rotation of the earth with incredible accuracy. Most often this mount is the most expensive piece of equipment out of everything else. The accuracy needed really is borderline unimaginable. For example, when imaging at an average "zoom" level, it needs to point the telescope in a fixed spot in the sky with an error of under 1 arcsecond. One arcsecond is 1/3600 of 1 degree. This is the equivalent of the width of a human hair at 10 meters away. Or the diameter of a coin at 2 miles. For now I won't go into too much details but things get complicated fast here. The choice of the telescope type is important according to desired targets, then there are specialized astronomy cameras which are much more sensitive than regular "earth" cameras 🙂 Power requirements, control software, cabling, specialized filters, optical correctors, spacers, focusers. Additionally, besides the main imaging telescope, most setups have a 2nd small telescope piggybacking on the main one with the sole purpose to guide it. What this means is that small telescope, with a separate camera looks at the star positions around the target and tracks the motion of the mount. Through dedicated software it sends very small correction pulses to the mount to have it track very precisely. This is how we reach that accuracy explained above. As expected, capturing the data is only part of the whole process. It can take many hours in all sorts of imaging software to bring out the details and stack the captured images. (big range from free to photoshop to dedicated astrophotograpy options) There are so many things that can and do go wrong so when starting out, inevitably there will be more troubleshooting nights than actual imaging time. It's part of the fun for me 🙂 But when things do work, and you find the target, start imaging and start seeing those invisible details, it all makes sense and the satisfaction is amazing. If you made it this far, let's go through some actual results. Currently I use 2 telescopes. One "smaller" 80mm refractor (385mm focal length) for deep sky objects and a big one (8 inch diameter) that I designed and 3D printed (1000mm focal length) to use on planets and the moon. This is the small one imaging away on a random night next to our apt complex: The big one, testing after I put it together. I still can't believe what details we're getting on the moon with it: The great conjunction, Jupiter and Saturn: The rest of the images are all with the smaller telescope. Total exposure times range from 1 - 7 hours per image. M13 The Great Globular Cluster in Hercules. Pretty amazing to see hundreds of thousands of stars clumped up so close: NGC2244 Rosette Nebula. Made up of clouds of Hydrogen Alfa and dust. The hydrogen Alfa particles emit this deep red light (around 656nm): M16 Eagle Nebula. This one should look familiar. The Pillars of Creation. It's the most famous Hubble image. I still can't believe I got to see it with my tiny telescope. M27 Dumbbell Nebula. This is a so called planetary nebula, created by the death of a star which pushes out incredible amounts of material. In the center there is a white dwarf. NGC7000 North America Nebula: Lastly, also incredible to me, I've actually captured some surface details on Mars. There are much better images out there but I did not expect to see something like this with my gear: 1 7 Link to comment Share on other sites More sharing options...
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