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About almcl

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    Telford, Shropshire
  1. Depends how much you want to spend. I started guiding with a £14 webcam, spare finder scope (free) and PHD (also free). It worked but couldn't always find a guide star. So upgraded to a Skywatcher ST80 from Ebay (£70) and a QHY5L ii mono camera (£150, although they are sometimes cheaper at the Astro show at Stoneleigh). This camera is amazingly sensitive and always provides a choice of guide stars. I do occasionally use the finder scope with the QHY camera (it comes with an adapter which screws straight in) and the results from this are OK as well.
  2. I use an ST80 with a QHY5L ii M which gives a field of view of 0.69° x 0.48° and Sharpcap polar align solves this with no problem, so might be worth trying without a Barlow to start with? °8
  3. More advice, please.

    I have had a go at your .fits file, and it looks as though the sky glow has rather overwhelmed the signal. There's also quite an amount of vignetting and an odd artefact at the top right corner. If you are able to take flats these will help with the vignetting and any dust bunnies, but the sky glow might require a light pollution filter. I had a similar experience (living in a heavily light polluted suburban area) and the use of a clip filter certainly helped. Not sure what's available for your Nikon, perhaps someone else can advise? The other thing is that for large targets like the Heart & Soul, a long focus camera lens (as Happy-Kat mentions) may give you a better chance of getting the target in frame. Alternatively, go for some of the smaller faint fuzzies, where your long focal length will be more of an advantage?
  4. Guiding other than with ST4

    +1 for the Lynx EQDIR, cable linked above. It's even clever enough not to mind which USB port it gets plugged into and I use it all the time with my AltAZ EQ6 with Cartes du Ciel as the planetarium program, APT as the capture software and PHD2 as the guider and they all seem to work very happily together under the ASCOM EQMOD setup. There is a little bit of setting up at the beginning but after that I am usually guiding within 10 minute of being set up.
  5. ADU confusion

    14 bit RAW images, I believe, so 16,384 ? (as per Oddsocks' brilliant explanations above)
  6. how do I find ADU values?

    There was a thread (which I now can't find a trace of) in which someone showed a screenshot of FITS Liberator giving values for pixels on the different RGB frames. I couldn't get it to work with my setup for some reason (no input values displayed by FITS Lib) but as it's a free program might be worth a download?
  7. Sorry, Olly, didn't see this till just now... I do have a trial copy of Astroart, but cannot get on with it - the interface is just too baffling and the output (on the odd occasion when I've got it to load and align some lights) a monochrome grainy grey with almost no detail present. Would dearly like a stacking prgram that doesn't muck around with the white balance, but haven't yet found one my simple brain can understand.
  8. Thanks for that bobro. I wasn't able to get the stars down to quite that level but with your and tooth_dr's help, I found the source of the issue! Just in case anyone happens upon this thread in future, it was a problem of registration data and for some reason I originally stacked using the intersection option with far too many (>2000) stars detected. Once the median filter was applied and the detection threshold set to 85%, plus checking the 'Register already registered pictures' box which habitually I uncheck (can't bear waiting 5 minutes for it re-register files it has registered already) and deleting the previous registration data (.txt files) then rerunning the stack, produced a normal image. Below is the same area as the 1st image in the thread, after the re-run (no idea why the colour is so radically different...)
  9. Isn't that the truth, TD! Almost certainly it will turn out to be operator error... That's a most generous offer bobro. Thank you. I've put jpeg versions (the raws would be a bit large) of the files here: https://www.dropbox.com/sh/t6g6yu4pe2a2w3q/AABxfTHbqE26hf--LIODL9Vda?dl=0 At the moment DSS is my only stacking program although I am on the lookout for one that doesn't white balance the output which StarTools would rather prefer.
  10. Tried using the median filter for stacking and while it did greatly reduce the number of detected stars (thanks for pointing me in that direction, tooth_dr) this didn't solve the stacking problem :-(
  11. Deep sky imaging showcase 2017

    IC1369A M8 M17 M20 M94
  12. Thanks both. I'll have a go with a median filter and report back. In the meantime here are the full size subs:
  13. Had a bit of disaster the other night and I wonder if the community would care to suggest what's going on? 16 subs all have reasonably round stars (Canon 200mm lens on Canon 700d, guided by finderscope and mounted on EQ6 ALT/AZ Goto) but when stacked in DSS, some really strange shapes show up slightly right of center at the top of the frame. The bottom is not quite as bad. Now I had poblems with guiding - the normally ultra reliable QHY5Lii was causing PHD2 to trip out with the 'hadn't captured a frame in 17secs' message. The flats had weird bits of dust and squiggly stuff on them. The ever present vicious amp glow was as bad as ever, the guiding was all over the place when the camera would connect and, of course, cloud rolled in before the required subs had been acquired. But what's causing the mis-aligned stars in the DSS output at the top but not the bottom? I can't get the number of detected stars below about 900 (at 91% threshold) if I increase the threshold to 92%, no stars are detected, so I wonder if some of the 'stars' are actually noise and it is this that is causing the mis-alignment? Below are a top and bottom crop of the output from DSS, stretched to show the shapes as well as the first and last subs and the entire output from DSS.
  14. It isn't the ambient temperature so much as the sensor temperature that you want to match. The EXIF data for some of the Canon cameras records this and APT actually records it in the file name. While my tests with a remote IR thermometer suggest that the EXIF recorded values may not be exactly what the sensor is at, they are a much more reliable guide than the ambient air temperature. You can build a 'dark library' with the camera off the scope, lens cap on and some like to put it in a light proof box as well, although I am not sure how necessary that is. I find doing this that the temperatures increase steadily during a dark capture session, so several runs are necessary to get enough say 10°C darks to match my lights from a previous night. If you don't have software to read the EXIF data, Michael Covington has a small program here that makes a neat job of presenting the info.
  15. Dinoco Well done! You've done much better than I did on my first outings a few years back. Something I found greatly improved my constellation recognition was observing from a dark sky site with an unobstructed horizon. Constellations that can barely be made out from my back garden (heavy light pollution) become far more recognisable when standing on a windswept piece of moorland 25 miles away! I also found Sky and Telescope's Pocket Sky Atlas very useful, particularly in conjunction with a piece of card with a circle cut out the same size as my binos field of view,. Now I try and sort out a couple of new constellations each season.