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About Demonperformer

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    51-ish N; 1-ish W
  1. I've been reading-up a little on resolution and airy rings. With an f/6 scope the formula I have found gives: 2.44 * 0.520 * 6 = 7.613μm as my optimal pixel size. My camera has 3.8μm pixels, which is almost exactly half the optimum , which would seem to imply that I would get better pictures by binning 2*2. Indeed, if I use the SCT @f/10, it appears I should be binning 3*3 to get as close to the optimum as possible. This would be great for exposure length (1/4 and 1/9 respectively), but it seems extremely counter-intuitive to me that my images would be any better. Is it right, or am I missing something? [Please don't suggest I need to buy another new camera with different pixels!] Thanks.
  2. Is QE linear in relation to exposure time?

    Probably expressed myself badly in the title of the thread. The point I am trying to get at is that, for a waveband with a lower QE (for a particular chip/camera) I would need to increase the exposure to end up with an image of similar brightness. If the QE is half does the exposure simply have to be doubled, or is it a more complicated formula (and if that is the case, what is it)?
  3. wifi telescope control

    This isn't quite the thread I remembered - a lot shorter than I thought and it seemed to stall half way through, but this is the thread that spawned it - much longer but contains some invaluable info. HTH
  4. wifi telescope control

    Will look it out for you when I am on my home computer.
  5. ngc 457

    Definitely my favourite of the Cassie-clusters. Nice one.
  6. wifi telescope control

    Gina has a thread detailing the process step by step.
  7. An object emits light in two wavelengths, x & y, of equal intensity (same number of photons per second). I have a camera that has a QE of 70 in wavelength x and 35 in wavelength y. I also have two filters, one for each wavelength (assume all other criteria for the filters are identical). To get images of equal brightness, would I simply need to double the exposure time for the image taken with the y filter, or is there some more complicated relationship between exposure time and QE? Thanks.
  8. Alan Gee Mark II Telecompressor

    Yes, I understand the general principle, but it is something specific to this model to which I need an answer. I tried posting on a different forum and got a string of answers to questions I wasn't asking and when I pushed for specific answers to my questions got a "Don't know, never used it" response! So I'm trying to find someone who actually has used one before I go into it in detail again.
  9. Alan Gee Mark II Telecompressor

    Does anyone on here have any experience of imaging with this device? Thanks.
  10. just saying hello

    "Hello" to you, Alan, and welcome. To take pictures of the night sky is a noble aim and when you start buying, I would agree that a good mount is all-important. But it is possible to take widefield shots with just your camera and a normal tripod. Go somewhere away from the streetlights, keep your exposures down to 15-20 seconds with a fairly short lens and you will get some lovely shots showing much more than you can see with the naked-eye. Have a look at this thread. Don't be misled into how much you can see, though. I don't think anyone has ever actually "seen" the squid nebula. It is incredibly faint and requires very long exposures with specialized filters to capture it at all. But enjoy what you can see. I suspect you meant to say that you have an 80 mm scope, not 80 cm? Thanks.
  11. After ages of failing miserably in my attempts to polar align I found polemaster to be invaluable. But I would agree that you should try sharpcap first - it's free after all. Don't spend money on things you can do without. BUT if you have problems, then polemaster should sort them.
  12. First attempt at the Horsehead & Flame Nebs

  13. Robotic recommendations?

    Thanks for all that, Ronin. I will chase down some of those leads (if they are still extant).
  14. first image post (very nervous)

    If my first image had been a fraction as good as yours, I'd have been ecstatic. Come to think of it, if my current images were a fraction as good as yours, I'd be ecstatic!