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About Ouroboros

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    Sub Dwarf

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    South Oxfordshire & North Cornwall Coast
  1. We're going back... it's official!

    Rumours have it that Donald will head the mission and that there are no plans to provide a return spacecraft. But he hasn't been told that bit.
  2. Doa! look what ive done

    Oooooher! Hopefully no serious damage to equipment. At least it's not your eyes.
  3. Bubble Nebula 25 Hours exposure in Sho and Hoo

    I guess you probably know this already but to my eye your images are those of a professional. Personally I think this is a fascinating object. Unfortunately I don't at present have the equipment to do it justice, let alone the skill. I prefer the second one, but both your images are exceptional. 25 hours. Phew! I doubt I've managed 25 hours of astrophotography in the last few years let alone on one object. But that's what's good about this activity - it can be enjoyed at all levels of equipment, time available and abilities.
  4. OK. So the same size sensor as mine. You'll get a slightly larger image size than I get with my 450D attached to my Evostar ED80 which has a focal length of 600mm. So the full moon will look something like the lunar eclipse image I took below. M31 is about 3 times the apparent diameter of the moon and will be nicely framed if you place it on the diagonal of the frame. That should give you an idea of the image size you'll get.
  5. Maybe you've said but what sort of DSLR have you got?
  6. One way to think about it I suppose is that a telescope is really a modified microscope for looking at distant objects. An eyepiece is really a microscope. The purpose of the primary lens or mirror is to collect as much light as possible from the distant object and to focus and project an image of it at (or near) the focal plane for close inspection by the eyepiece (microscope). The size of the image formed by the primary lens or mirror is proportional to its focal length. The longer the focal length, the larger the image. With my Canon 450D DSLR attached to my 1000mm Newtonian telescope the full moon almost fills the short side of a full image. The same camera attached to 700mm telescope would provide an image in which the full moon was 0.7 times smaller. Just over half the size in other words. Of course the actual size of the full moon on the OP's DSLR will depend on the size of the sensor. But in approximate terms, even if it's a full frame DSLR, I would expect the OP's telescope to give an image of the moon about half (or slightly more) the size of the full image.
  7. Ah! Problem solved it seems. On closing Pixinsight it installed further updates which when I ran Pixinsight again the missing icon reappeared. Sorted!
  8. I've just updated my PixInsight to the latest version. My PI desktop is missing the luminance extraction icon in the toolbar. It normally sits next to the little icon to "Split the RGB Channels" in the centre of the screen shot below. I can't see how to recover it. Anyone know?
  9. Quantum Physics tonight

    Jim A is pretty good and programmes like this were made as primers for the Open University I think so they're a bit above the Brian Cox level. I sometimes wonder whether it is more confusing to use analogies to try and explain things like quantum mechanics than it would be to actually teach people some physics. I discussed the programme afterwards with my OH, who is not daft by any means, but she doesn't have a scientific background. She found the analogies too muddled and convoluted. So I explained about photons and polarisation and the supposition of states and the creation of entanglement in simple terms and she said yes I get all that, why didn't Jim A say that instead of muddling it up with coins and gloves and whatnot.
  10. The cosmetic correction in DSS for the removal of hot pixels works well IMO. I tried it recently on some data for which I didn't have darks and it was very effective. I'm wondering what the best parameters are. I used Filter Size 1 pixel and Detection Threshold 33%. I'm not sure what detection threshold actually means. The help file is not exactly helpful on this. It describes it as the threshold under which no correction is done. But threshold of what? Apparently the lower the threshold value the more corrections are done. So better start high and work down I guess.
  11. The River Kent in Cumbria

    Interesting! With a wide angle lens you've got to put the horizon, if there is one, on the central line haven't you otherwise it's always curved? I have a fixed 8mm Samyang fisheye lens which is fun to use and can produce some very interesting wide angle shots. Great for sea scapes where the tide is receding and you get the sky reflected in the wet sand.
  12. The River Kent in Cumbria

    Great picture. I like the mud! "Mud, mud, glorious mud!" I loved your account of taking the picture too. Not enough people do that. There's more than one picture in this picture isn't there. For example zooming in one can put the horizon line at the lower 1/3rd point and hence see proportionally more sky. I'm wondering why you had to take this photo in panels. You've got a very wide angle zoom lens there. Unless it's to enhance resolution of course, or maybe it helps remove the distortion seen in very wide angle photos. Sorry if I'm displaying my ignorance of this sort of photography.
  13. Thanks. PI is a fantastic application. I'm very impressed with it. But frankly it's a bit like walking into the flight deck of a jumbo jet and trying to work out what all the buttons are for let alone how to use them. My picture was produced by a bit of cheat really. I found a promising tutorial on YouTube and simply followed the work flow. I just tweaked each stage to suit my data.
  14. Yes, I suppose it's not like the latest canon SLR or Apple phone is it which are produced in bulk and initially marketed at a premium and then gradually reduced over time.