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opticalpath

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Everything posted by opticalpath

  1. Great to see these wonderful images, and I'm looking forward to seeing your rendition, Olly! I didn't find much detail in the OIII when I did this a while back. This was 15 x 1800s OIII, binned 2x2. Using just the NB for nebula colour, I found it hard to get the balance of blue/ green and brown tones .... and concluded that a LOT of RGB would probably be a better starting point to get the right colour balance. Adrian
  2. That worked beautifully, Sara .... great result! You described the workflow as 'simple'. I think maybe what you mean is that you've mastered it and now it seems straightforward to you; the rest of us just wonder at it! Adrian
  3. Another beauty, Sara. Great to see it at this resolution. Well done! Adrian
  4. Another bit of bi-colour magic, Sara; how you get so much out of two filters I'll never know! It's very atmospheric with the dark shadow areas and contrasting 3D-like pillars - a great result! Adrian
  5. I echo everyone's comments, Chris: a beautifully detailed image and just amazing for the short exposure time. Adrian
  6. I'm sorry you had such a bad experience with your Moonlite, Olly. I must say I'm pretty happy with mine. It's carrying quite a heavy QSI camera package and gives repeatable, slip-free focusing with my DIY stepper motor belt drive. When I set it up at the beginning, it did need some adjustment of the tension screw - enough to lift the imaging train (plus a little extra weight for contingency) vertically without any slip, but not so much as to stall the motor drive. That was quite a long time ago and I haven't had to touch it since; it just seems to work every time and I don't have to think about it. The digital focus position moves a little as expected with temperature changes but otherwise seems rock solid. In fairness, with my (Mak-) Newtonian focus position, in practice the focuser is not often required do anything approaching a vertical lift, so it's not tested so severely in that respect as it would be in a refractor. I don't think anyone would ever go wrong by choosing a Feathertouch focuser, but I thought it was only fair to report one positive experience with a Moonlite. Adrian
  7. Whew ... this is a bit special, Sara! Wonderful just as it stands in mono ...... but I can't wait to see what you do with bi-/tri-colour too. Adrian
  8. GULP! Inspiring stuff, Ollie. Soo much to see .... and I really like the subtle colour treatment. Adrian
  9. It's a beautiful image, Sara! One of my favourite objects. Super job on the processing: the detail in the dust lane is wonderful and I especially like how you've controlled the sharpening: startling detail in the dust but a softer smooth glow surrounding it. This is nit-picking, but I would say your star colour is a tad warm. Some white stars look a bit yellow to me, and in this field to the right of the galaxy there is actually a very blue star (c. index -0.27), that is not really showing its colour. Adrian
  10. Just catching up and saw this. Whooo, that is something, Sara - so much detail at this scale! Beautifully done. Much as I love it in mono ..... can't wait to see the bi-colour version. Will you merge in some RGB for the stars or stay NB-synthetic? (6.5 hours per night in June . There's latitude for you!) Adrian
  11. That's a remarkable result with a modest set up and in such difficult conditions. Really well done! Adrian
  12. I might have confused things by referring to 'studs'; I didn't mean threaded-rod type studs. I just meant that the base plate of my mount has three integral very slightly (few mm) raised 'bumps' on the underside. They just ensure that the mount base makes positive 3-point contact with the pier top when the mount is bolted down. The idea of shimming was to completely eliminate any threaded support legs, relying only on the clamp-down mounting bolts and shimming the mounting feet, so keeping the gap between mount base and pier top to only a few mm. Adrian
  13. If you're concerned to get the mount level (and I quite agree it's not essential) the simplest way I found is to put fixed spacers between the base plate of the mount and the top plate of the pier. The flat underside of my mount has three slightly raised studs 120 degrees apart that are the only points of weight-bearing contact between mount and pier top plate - I suspect other mounts may be similar. My pier top-plate is not quite level (in fact it's not quite flat!) but it was dead easy to make up a few thin metal shims to place under the contact points to make the base of the mount level - permanently. Adrian
  14. Wow, what a field of view ..... great work! Adrian
  15. Really nice! You have avoided the contrasty and over-sharpened look that afflicts many images of globulars, without it looking soft. Stars are clean and colourful. Adrian
  16. Thanks for your kind comments, folks. Adrian
  17. One of the potential weaknesses was that the cable connecting panel to inverter was thin and rather inflexible - possibly solid-core copper conductors rather than flex - and didn't respond well to frequent handling/ bending. I wonder if that has been changed. Adrian
  18. Great news, Olly. From 'flat broke' to 'luxury flat'. Finally got that stone out of your shoe. Adrian
  19. Very true, especially so with such a wide FOV .... or is it just pixel scale that matters for sensitivity to field rotation? I can't work it out. Probably both. When I was starting the 'headphones' project, I considered doing 60 minute Ha subs. I might have got away with it but I chickened out! (Think of the darks ) This was a test shot - a single one-hour sub at 1.1 arcsec per px, calibrated and stretched a bit: http://universalconstant.com/PK-164-001H3600.jpg Adrian
  20. Wow, what an eyeful . Superb, Olly. Adrian (BTW, and this is really being hyper-critical .... is that just a wee bit of curvature or rotation creeping in to the left side of the image? Only visible when pixel-peeping the full res. version)
  21. Seeing several excellent images of the 'Needle' posted recently by members prompted me to go back and have another go at processing one of my own efforts from a while back. I think this is a worthwhile improvement with more detail extracted in the dust lane. It's 6.4 hours luminance (1x1) and 3.2 hours RGB (2x2), taken with a SW MN190 and QSI583 with OAG. This is a crop of the central area. A wider field view can be seen here: http://universalconstant.com/NGC4565_AP_crop2.jpg
  22. With the Lodestar and 3 sec. guide exposures I found that I got quite a few hot pixels that were occasionally troublesome. Dark calibration solved that, and probably improves the SNR enough to make fainter guide stars usable, so worth it I would say. Mind you, with 5 sec. guide exposures, I don't suppose there's any shortage of guide stars! Adrian
  23. A blob of hot-melt glue is useful for this kind of reinforcing at the cable exits. With a little practice you can use wet fingers to pull the setting glue along the cable and shape it into a tapering sort of strain-relief grommet that sticks securely to the panel or power supply box, and provides a semi-flexible support to the exiting cable. The tapering-off-to-nothing of the glue support on the cable is important so that the support reduces smoothly and you don't produce an abrupt hard edge where the support suddenly stops, creating a new stress point. Adrian
  24. Now that is my kind of DIY, Olly! I bet it works a treat. Function over form every time. Adrian
  25. Agreed, and for most of us sky background is the biggest source of noise in practice; in average UK conditions it tends to overwhelm every other source. What I meant was, in this special case of relatively very short exposures (and especially with narrow-band filters) sky background is much lower in each exposure, so read noise could become a more significant issue, especially if the object signal level is very low too. However I have to agree that the examples referred to in the posts above, taken using the newer very low noise CMOS cameras, speak for themselves: very impressive. Adrian
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