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endlessky

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About endlessky

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    Star Forming

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    Padova, Italy
  1. I use a Raspberry Pi 4, running Astroberry, attached to the mount. All the gear (DSLR, guide-camera, mount and USB 3.0 memory stick) is attached directly to the Pi. I use is as a hotspot and use VNC Viewer from my laptop to remote desktop in the Pi. KStars/EKOS are run directly on the Pi. The files from the D5300 (around 24 MB) take about 2.5s to download on the Pi and get transferred to the USB stick. The problem is not the stick, or the speed of the Pi, itself, because I tried saving directly on the Pi SD card, or on a hard-drive connected to the USB 3.0 port, and it always takes the same amount of time. The problem is the USB connection out of the camera: it's only USB 2.0, so it doesn't matter where I plug it in or what type of storage I use or how fast it is, the bottle-neck is the port of the camera.
  2. Maybe internal reflections due to the filter. The only way of knowing for sure would be to try some test shots without (just pick a field with very bright stars, for example - perfect for this period - the Pleiades).
  3. Hello, the filter that you want removed is not the IR filter, but the stock filter that comes with most DSLRs. This filter blocks most of one of the most important wavelengths when it comes to a lot of nebulae: the H-alpha. The stock cameras would block anywhere from 75 to 85% of the light, in this particular wavelength. When people astromodify their cameras, they actually put an IR cut filter back in, otherwise - if they left the camera full spectrum (without any filter at all) - the stars would be bloated / have halos around them. This is because lenses/refractors are not able to focus all wavelengths in the same focal plane and IR light would not be focused as well as the rest of the - useful for astrophotography - wavelengths. Modifying my Nikon D5300 was one of the first thing I did. After I "wasted" four hours on the Chrismas Tree Nebula without gathering any satisfactory amount of signal, I knew that if I wanted the results I was after, I needed to modify the camera. The difference is night and day and - if you use the camera only for astrophotography - it's entirely worth it. The next step would be to buy a dedicated astrocamera, but the price range for these is a lot higher than buying a used DSLR and modifying it yourself / having it modified by some store that offers the service.
  4. In this hobby, it seems we are always waiting for something. Waiting for equipment, or waiting for clear skies...
  5. If the sensor dimensions are indeed wrong, the computed field of view will be wrong as well. It could possibly be due to the fact that the camera wasn't connected, I don't know for sure, though. I have used APT a long while ago and now I use KStars/EKOS, because I am running my gear from a Raspberry Pi 4. I would try again with the camera connected. Also, about your workflow, it seems pretty much what I would do. But, as stated above by Ivor, I would add a step for fine focusing. Plate solving can work also if the focus isn't perfect, though. Another tip: you don't need to wait for precious clear sky nights to do some experiments with your gear. That's what the cloudy nights are for. Set up your mount inside the house, roughly pointing at Polaris general direction. Load an image of an object that you already took (better if a single frame, unstretched - as it would come out of the camera during a "live" session) and ask APT to plate solve it and to slew to it. Watch where the mount is pointing to at the end of the slew. Does it make sense as to where the object could really be at that time of the day in which you did this? Then you can immediately have a general idea if things are going in the right direction. If you haven't added one, yet, I would also add a planetarium software to your mix - it makes things a lot easier when it comes to find what objects are available, when, and where in the sky, from your particular location. They also integrate with the software you use for imaging and plate solving, so you can see on the planetarium where your telescope is pointing. There are a lot of free ones. One I particularly liked while I was using Windows and APT was Cartes du Ciel. Now I use KStars, with the Pi. Last thing: if you want a really nice online resource to check for objects availability from your location and also to check framing and field of view with different cameras/lenses combination, take a look here: - Telescopius.com - Telescopius.com - Telescope Simulator With the second link you can input your imaging focal length and your camera sensor size. Then you search for objects and you'll immediately be able to see how big - or how small - they will look in your image. If you register an account with the website, you can save all your cameras and lenses, your location and your preferences. I really find it invaluable, because I can also filter the target list by object type, magnitude, minimum altitude, degrees away from the Moon, etc. Once you install the planetarium, you can have it display your saved field of views and tour the sky and immediately see how the available objects will fit in your frames, as well.
  6. Once I learnt about the dark magic art of plate solving, the handcontroller has been safely resting inside a drawer and won't see the light - or rather, the night sky darkness - any time soon...
  7. The first few times I used plate solving I considered it sort of miraculous as well. Then you get used to it and actually get mad when it doesn't work, but that's another story... You can actually link plate solving directly to AstroPhotography Tool, so that it can plate solve immediately and help you figure out by how much you are off your target. Another beautiful feature is that it will keep solving and slewing repeatedly until it's pretty much centered dead on your target RA/DEC coordinates. Take a look here on how to integrate plate solving into APT, if you are interested: Point Craft and Plate-Solving
  8. Glad I could be of help and glad that it worked!
  9. It might be the shadow caused by the shutter. How long are your exposures for flats? I read somewhere the advice when using a DSLR: to avoid shadows caused by the shutter, you should avoid short exposures. I use a DSLR as well, and I double the layers of cloth, to make sure my exposures are at least higher than 1 second. They seem to work fine, not causing any shadow issue (that then would translate in lighter parts on the calibrated images).
  10. So, I took the rig out last night (October, 7th) for another session. I removed the L-Pro filter, to have less variables in the mix. I also took four pictures of the same star field and same exposure time, rotating the camera (D5300) - using the telescope built in camera rotator. I started with the camera at 0°, then 90°, then 180° and finally 270°. I even tried doing the same tests with the D90, and got pretty much the same results. So, it seems camera independent. I feel I can rule out tilting, since the star shape stays pretty much the same in the corners, independently of camera rotation (for example, same top left corner for all for images present same star shape, and so forth for the other corners). The star shape is also more consistent, and they all look elongated in an orientation perpendicular to radial. To me it's quite possible that the camera sensor is a little too far from the flattener/reducer, meaning I should somehow shorten the distance. I also don't think the filter had any fault in the way the first pictures turned out, since the star shapes in the pictures without filter and in the pictures with filter are pretty much identical. I emailed the store where I bought it describing my concerns. I will see what they suggest to do. I tried calling, but my call got redirected to another Tecnosky store and I spoke with somebody else that wasn't the person that have been following me for all these months. He suggested to try adding distance, first, and see if that works - since at the moment I have no way of removing distance, other than buying a low profile T2 Nikon ring. We'll see how things develop from here onward.
  11. So, I took the rig out last night (October, 7th) for another session. I removed the L-Pro filter, to have less variables in the mix. I also took four pictures of the same star field and same exposure time, rotating the camera (D5300) - using the telescope built in camera rotator. I started with the camera at 0°, then 90°, then 180° and finally 270°. I even tried doing the same tests with the D90, and got pretty much the same results. So, it seems camera independent. I feel I can rule out tilting, since the star shape stays pretty much the same in the corners, independently of camera rotation (for example, same top left corner for all for images present same star shape, and so forth for the other corners). The star shape is also more consistent, and they all look elongated in an orientation perpendicular to radial. To me it's quite possible that the camera sensor is a little too far from the flattener/reducer, meaning I should somehow shorten the distance. I also don't think the filter had any fault in the way the first pictures turned out, since the star shapes in the pictures without filter and in the pictures with filter are pretty much identical. I emailed the store where I bought it describing my concerns. I will see what they suggest to do. I tried calling, but my call got redirected to another Tecnosky store and I spoke with somebody else that wasn't the person that have been following me for all these months. He suggested to try adding distance, first, and see if that works - since at the moment I have no way of removing distance, other than buying a low profile T2 Nikon ring. As for guiding, I run Guiding Assistant and optimized the settings, with its suggestions. It also gave me a polar alignment error of 3.4 arc-min, after I let it run for 5 minutes. I must admit polar aligning was very easy last night, since by the time I was ready to polar align, the app showed me that Polaris needed to be almost exactly at the 9 o'clock position as seen from the polar scope. I did a 2 hour session on the Heart Nebula, and guiding stayed well below 1" RMS for the whole duration (excluding the dithering peaks, the RMS was between 0.65" and 0.85"). After a while I wondered if I could make it even better, so I remembered the "east heavy" rule. I stopped the imaging session, slid the counterweight a few centimeters down from where it was, and sure enough, after I resumed guiding and imaging, the RMS was now between 0.45" and 0.65" - more than a good 25% less, just by moving a counterweight. Amazing! I'll post it after I finish some processing. If in the next couple of nights it's clear, I would like to add more data to it, as well.
  12. I have already posted my first astrophotographic session report in the telescope review thread: Tecnosky 80/480 APO FPL53 Triplet OWL Series - Review. But since that is more of a general review/diary of my experience with the new telescope, I feel some of the issues I am having are being buried and they will probably get more visibility if I post them - in a more synthetic version - in a dedicated thread. So, a few nights ago (October, the 5th) I took out my new telescope for its first light. All the photos have been taken with the 0.8x flattener/reducer and the Optolong L-Pro 2" filter attached to the reducer. The camera is an astromodified Nikon D5300. The only processing the following pictures have consists in this: - AutomaticBackgroundExtractor - ColorCalibration - Stretch Here we have a 90s shot of M31. And here's a mosaic generated with the AberrationInspector script. What I do like: - tightest, smallest, roundest stars I have gotten since I started doing astrophotography at the end of January. Obviously comparing it to what I have been achieving with a kit 70-300mm zoom lens, these can't be anything else but better by orders of magnitude What I don't like: - star shape not consistent in all areas of the image - residual chromatic aberration, especially on stars that are not round: there's clearly some red and blue edges visible I didn't expect this from an apochromatic refractor, but maybe it's just because the stars are kinda "smeared", so not all light is focused at the same spot? I don't see this around the center of the image (or, at least, the problem is less pronounced). Maybe I have some tilting in my imaging train/sensor? I have been doing some reasoning about it and it seems like a combination of tilting and/or backfocus spacing. According to the following image about backfocus spacing: if the stars are elongated radially, the sensor is too close, if they are elongated tangentially, the sensor is too far. But to me it seems I have a little bit of both: in the top right corner, for example, the stars look radially elongated, in the bottom right, they look tangentially elongated. Top left they look tangentially elongated, bottom left also, but a little less. Seems like there has to be some tilting as well, otherwise they would all have a symmetric shape on all corners, correct? How do I determine - is there even a way - if the issue is due to tilting only, backfocus only, or the combination of the two? Is there a sure proof way of checking for tilting? Like, rotating the camera and taking pictures with, say, the camera at 0°, 90°, 270° and 360°? If there's tilting, the pattern of the star shapes should follow the camera, correct? I also tried splitting the channels in R, G, and B components, doing a star alignment of the blue and red channels with the green as a reference, and recombining the channels. The blue and red edges become a lot less evident, which is good, but obviously the star shapes remain the same. In my Telescopius gallery you can also find two other images, Capella and Capella Mosaic showing pretty much the same issues. Also, one issue with the guide camera: ZWO ASI 224MC. When attached to the guide scope (Artesky UltraGuide 60mm f/4), I can't seem to get a "sharp" focus, I even tried on the Moon, and the best I got was a soft lunar disc, with some major features visible, mainly by change of color/brightness (the maria, for example), but no details. The image still seemed blurred/bloated. Is it because of lack of IR blocking filter? I tried the same camera attached to the main refractor, with the L-Pro filter (which blocks UV and IR, as well) and I could focus perfectly. Do I need an IR block filter for guiding or even if the stars appear a little soft, the camera guides just fine? Matteo
  13. Thanks for the tips. I must say I pondered the idea of the "lack of focusing" being due to the fact that I have no filter in front of the 224MC and that it's a camera very sensitive to IR. I guess I'll try the 224MC paired with the APO and see how it goes. It should give me better focusing and also prove if the star shape is due to the spacing of the DSLR, as you suggested. I know star shape depends on how close to the correct backfocus you are, and if I need to go further than where I am now, I see no problem (I can always add). But if I needed to go closer, I don't know how I will be able to achieve this. The Nikon T2 ring plus the distance between the front of the camera and the sensor already give me 55mm, and I don't see how I could reduce that distance...
  14. Last night, October, 5th, I took out my rig for the first "real" testing of the OWL in its astrophotographic configuration. Here's a picture of the whole setup, taken just a few moments after setting everything up. I started setting up around 7:30 PM and was ready a while before astronomical darkness, around 8:00. I started tearing down and bringing back inside my gear at around 1:00 AM, so I spent a good 5 hours out there testing things. First thing I did was a rough polar alignment, using an app on my phone and eyeballing Polaris in my polar scope. Clouds were constantly rolling in, so I had to "chase" the clear sky patches, never settling on one particular zone for more than 5-15 minutes. I used the Bahtinov mask for focusing and was extremely surprised on how easy it was to judge and adjust focusing, even if I couldn't do it "live" with the DSLR, but I had to take a picture, adjust, take another one, adjust again, and so forth. After a few minutes, I decided the focus was pretty spot on, removed the mask, and took a 10s test shot. I was immediately amazed by how small, tight and round the stars were - to my standards, of course, coming from a 70-300mm kit zoom lens that is more useful as a paper weight than for taking astro pictures... I took a few short pictures here and there, with the focal reducer/flattener and the L-Pro light pollution filter installed. I even tried guiding, first with PHD2, then with EKOS internal guider. I was glad that the calibration procedure worked and successfully completed, in both cases. With my first PHD2 guiding, using the default settings and algorithms, I was able to go under 1" RMS (0.75-0.85") and was quite happy. Can be better, but nothing to complain about for my first automated guiding ever. I later tried with EKOS, using multi-star guiding and predictive PEC, but the guiding actually got worse (around 1.25-1.5"). My mount period is around 480s, and I never managed to guide for longer than 5 minutes, before having to move to a different spot in the sky and restarting the guiding process all over, so I hope it's just a case of not giving the guider enough time to "learn" the periodic error and adjust for it. Definitely have to try this again with more stable weather. Another thing that baffled me was focusing the ASI 224MC through the 60mm f/4 guide-scope. The focus always appeared "soft", even when the light source was a small as possible. What I didn't try was using my smaller Bahtinov mask and try to focus with it. I did, however, try to focus directly on the Moon. No matter what kind of gain and exposure time I used, the "best" focusing I could achieve was the Moon disc, with hints of its surface different areas, the maria definitely visible (with a different color than the rest, so the exposure was fine), but nothing crispy, no detail whatsoever. It didn't even matter what type of bit settings I chose. Is this expected behavior with a guide-scope? I don't think there's a backfocus distance to be respected when using a guide-camera / guide-scope combination, since there's no flattener/reducer attached. Right? Other problems encountered: with a guide-camera I thought I could finally take advantage of better polar alignment tools, since with a single-shot DSLR is pretty much impossible. So I did both EKOS and PHD2 static polar alignment routines. They work pretty much the same. For both, you point the telescope at Polaris, in the home position. With EKOS, it takes three static pictures, one in the home position, one after rotating the AR 30°, and another one at 60°. With PHD2 it uses the guide-camera and does this "live" by rotating the AR axis and monitoring the movement of a chosen reference star (I chose Polaris just to make sure I didn't input the wrong star) in the guide window. At the end they both give you an error and a vector for where Polaris is supposed to be. With EKOS I got around 9', with PHD2, 80'... So, I don't know how much I can trust these. What I didn't try was drift polar alignment, which I am sure will work much better and reliably. I will definitely do that next session. What else to say... Time for some first lights. The only processing the following pictures have consists in this: - AutomaticBackgroundExtractor - ColorCalibration - Stretch Here we have a 90s shot of M31, with L-Pro filter and 0.8x flattener/reducer. What I do like, as I said above: - tightest, smallest, roundest stars I have gotten since I started doing astrophotography at the end of January What I don't like: - star shape not consistent in all areas of the image - residual chromatic aberration, especially on stars that are not round: there's clearly some red and blue edges visible I didn't expect this from an apochromatic refractor, but maybe it's just because the stars are kinda "smeared", so not all light is focused at the same spot? I don't see this around the center of the image. Maybe I have some tilting in my imaging train/sensor? Here's a mosaic generated with the AberrationInspector script. Here we have a 95s shot of Capella and surrounding star field, with L-Pro filter and 0.8x flattener/reducer. What I like and don't like - same as above. And here's the mosaic.
  15. Thank you, Steve! I can't wait for some clear skies to start testing it properly. I'll post some pictures here as soon as I'll be able to get first light. The Whisky sure was a necessity. I like Scotch, especially those with a smoky taste. The beer was also very good, if you like sour beers. If you haven't ever tried one, definitely worth the experience. I'd suggest to start with the fruity ones, since the plain ones tend to be very sour and tart, and if you don't expect it, they could ruin the experience.
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