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BrendanC

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Everything posted by BrendanC

  1. You're right - I'm not that bothered...
  2. I really, really, really, really, really, really, really, really, really, really, really, really, really, really, really, really, really want to see this: https://www.thehuntforplanetb.com/ If this other doc of his is anything to go by, it'll be great: https://www.youtube.com/watch?v=FLD9LKq0u9E However, despite there being several reviews of it online, and even asking about this on their Facebook page and on Twitter, I cannot find it anywhere online to stream/watch/download/buy/whatever. Does anyone know anything about availability or release date in the UK?
  3. Thanks, I'll give it another go if you think it'll work, but I've never been able to get anything decent out of it! I'm just wondering whether I'm correct about losing data if I use the Kappa Sigma stacking method. I think the maths is such that I would lose data, and I've seen people use layers and masks instead. If I'm wrong about losing data then I'll carry on as before. Thanks for responding.
  4. I know this question has been asked quite a lot, but as I say, I haven't seen anyone cover the issue of whether data would be LOST using this method!
  5. I've been thinking a lot about stacking in DSS recently. Here's one of those thoughts. Say I have 100 exposures of a galaxy at 60s, and another 100 at 240s. I know that I could stack them all in one go in DSS, assuming I correctly allocate the calibration frames etc. I also know that this would improve the SNR. But, in doing so, how would the maths work for the fainter stuff in the 240s exposures? I have a sneaking feeling it would average it out from what it can see in the 60s exposures. I tend use to use Media Kappa Sigma for my lights, and I know that there's an algorithm that's supposed to be ideal for this, called Entropy Weighted Average, but I've tried that without much success. The alternative approach is to stack them separately then combine in Photoshop using masks and layers. But then, I wouldn't benefit from the improvement in SNR that way. The noise would just be greater in each stack. So what's the best way to do this? Is it, as is always the case, 'it depends'? I've been through lots of posts about this, both here and elsewhere, and I don't see anyone addressing the issue of potentially losing data from the 240s exposures by stacking them with the 60s exposures. Thanks, Brendan
  6. It's a Präzisionsokularauszug with an Okularauszug included. £1,143 per syllable.
  7. Yep, you've got me bang to rights on that one. I know nothing about Takahashis. In fairness I did say very roughly, in the same semantic sense that an elephant is very roughly a hippopotamus. Anyway, as I said, I wasn't being entirely serious. But I do still think, even with all the fancypants optics and your hyperbolic wosnames and your correcting widgets, it's an eye-watering amount to pay for what really does amount to two mirrors.
  8. I was idly browsing just now and wondered to myself: "Does Takahashi do Newtonians?" As you do. They do. And the very rough equivalent of my trusty Sky-Watcher 130PDS, currently retailing at £229, is this. For £2,398: https://www.firstlightoptics.com/telescopes-in-stock/takahashi-epsilon-130-ed-f3-3-newtonian-astrograph-reflector.html Now that seems a lot of money to pay for what is essentially two mirrors! A bit of maths-related fun: it seems to me that the primary is the same size for each, while the 130PDS has a secondary of 47mm and the Tak's is 63mm. This means that the 130PDS has a total surface area of 60,033 square mm, and the Tak's has 65,562. So, with the PDS it costs about 0.38p per square mm of mirror real estate, but the Tak is 3.66p. I'm not being entirely serious here, but I am curious as to why/how what are essentially two mirrors could cost so very much more? I can understand that hi-tech or moving parts, or luxury items swathed in leather and Swarovsky command a premium. And yes, I'm sure the scope itself is made of better/more robust materials with more precise collimation and so on. But they're still just... mirrors?
  9. No worries, I have my answers now. Everyone's been very helpful, as usual.
  10. Great response, thanks Olly. Quick thought though: when you say that the luminance data would come through from the OSC, would that still be the case if the OSC image was blurred? Because that's what I've done in the examples above, precisely to get around that problem. I can still see that this idea might not work though. Thanks for the honest opinion!
  11. Thanks! I can see that it's definitely better with two scopes, but I'm unlikely to be doing that. Also, getting the same FOV and orientation would be tough (it took a while to align the examples I gave) but I daresay the colour shot doesn't have to be pixel-perfect. Hmmm, food for thought...
  12. Thanks! I use StarTools which seems to bring out the colours nicely. Having said which, I never seemed able to get enough of the nebulosity towards the outer fringes of the Rosette which I see other people getting. You're right about the Andromeda shot - well spotted! It's a mosaic of four shots for the skies around it, plus a central pane which I captured much more time on. Here it is:
  13. Interesting idea! But I wonder how undoable that is?
  14. Here's another example, using a slightly better image of mine. Colour: Mono (from here: https://stargazerslounge.com/topic/326197-ngc-7000-hyperstar-c925/) Combined: It works better when I blur the colour image behind, and overlay the mono image. Now I look at this, I'm not sure it'll work. But I'd still be interested if anyone else has taken this route, and with what level of success. It would just be good to keep using existing equipment and upgrade one step at a time rather than wholesale change. I've come across some threads on Cloudy Nights where people say this works, but nothing here. Thanks, Brendan
  15. Hi all, I've been imaging with an EOS1000D with IR filter removed for the past couple of years. Had a whale of a time with it, and it works very nicely in my Bortle 4 skies. However, I may be moving to London soon, and I'd very much like to continue this hobby, even though it's probably the worst place in the world to do it! So, I've been considering narrow band imaging, cooled mono cameras, filters, filter wheels, all that gubbins. But I recently had a thought: instead of going straight from DSLR to mono with filters etc, and all the steep learning curve and cost that entails, could an intermediate step be to just get a cooled mono camera for the luminance, and combine that with shots from the DSLR for colour? I just tested this by combining my shot of the Horsehead - one of my first ever DSOs and I know there's a ton wrong with it, but it's just for the colour - and combined it with a shot taken from https://www.astrobin.com/full/397555/B/ for the luminance, using the Luminance layer blending mode in Photoshop. My colour version (over exposed, too much stretch, noisy, etc etc): Rick Wayne's mono version, which I've linked to above: Combined - just very roughly, just as very quick test: So in theory this is possible, even if the test image above is a little rough and ready. For example I can see that it's a bit noisier than I would like, but I don't know whether that's just me being a bit fast and loose with the overlaying etc. Is this a 'thing'? Do other people do this? Is it a valid intermediate step between OSC with a DSLR, and mono? Or should I just take the full step and go for filters too? I tend to shoot nebulae and galaxies, although I'm prepared to believe that one or the other (or maybe both) won't be possible from The Big Smoke. Thanks, Brendan
  16. Thanks! It depends. For clusters I can generally get away with a couple of hours. Galaxies about five. Nebulae about seven. More integration means less noise but also, oddly, I've noticed that the colours also definitely improve a lot with integration time too. I also use calibration frames - darks, dark flats, and flats, no bias. I take 25 flats on the night, have a 25-frame-based master dark flat that I re-use, and then a darks library for different temperatures. I know you're not supposed to use dark libraries with DSLRs, but what I've found through extensive testing is that they really do work, for me at any rate.
  17. Thanks! Yes it's a fabulous little performer.
  18. As we come to the end of another astro season, and the light nights mean no astro darkness from end of May until end of July (in the UK at least), I thought I'd post some of my shots taken over the past year since I got a second-hand NEQ6 and sold my 130P AZ. It was a huge step-up and I had to improve my technique because the improved accuracy of the mount really showed up all the things I was doing wrong. Anyway, now I've learned about guiding, calibrating, dithering, polar alignment and whatever else, I love my little 130PDS. The only thing I wish I could change is those iddy-biddy little bitemarks the focuser tube takes out of stars. All photos taken with an EOS1000D with IR filter removed, some are guided, others not, captured with APT, stacked in DSS, post-processed in Affinity and Topaz AI Denoise. They're all pretty much 'the usual suspects', they won't win awards, but I've really enjoyed taking them (as well as being very, very frustrated a lot of the time!). I hope it's OK to share so many in one post...
  19. There is such a thing as a dumb question btw. I was once asked by someone at work whether the Moon was bigger than the Earth.
  20. For some bizarre reason my mount refuses to slew to NGC 7822. No idea why.
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