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Pompey Monkey

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Everything posted by Pompey Monkey

  1. I have an "identical" no branded guide scope. It works fine, BUT... I needed to add two extra locking screws to the sliding part of the focuser as it was flexing like mad! I believe that the holes are already drilled and tapped in the tube - M4 or M5 I think. Once focused, I "carefully" nipped up the three screws and now it is solid. I'd be interested to hear if a similar problem exists with the branded versions...
  2. Bias: Yes Flats: Yes For a non-cooled DSLR, darks and dark flats are pretty much the proverbial "urinating into the prevailing airflow" for reducing noise. and can actually make things worse. If you are guiding, then implement an aggressive dithering plan (min 12 pixels between subs) and use sigma pixel rejection in the stacking process. If you are not dithering, then you really should. This is the most effective noise reduction method for DSLR imaging.
  3. Yes you did I agree that subtracting the uncalibrated darks also removes the bias from the lights. I just prefer to remove the bias from all my files so I know that I have "a level playing field" from the start.
  4. Wow! that's a lot of explanation. Thanks. The way my, rather limited, interpretation is if you subtract the bias (and dark if necessary on long exposures), then: Flats (Vignetting/dust bunnies) are a multiplicative correction factor, Gradients are subtractive. Yes/no?
  5. It's the little things that count...
  6. They do indeed add a constant value to the image to avoid negative numbers. However, this is a constant and is called the pedestal. It is not the bias signal. The bias is electronic noise generated by the sensor and camera electronics as the image is read off the chip. Fortunately, this noise is fairly consistent for every image read and, by averaging many bias files, a model can be built ("master bias") that can be subtracted from every image to dramatically reduce the read noise from the camera/sensor. Bias should be subtracted from every image read from the camera i.e. lights, flats and darks. Except bias frames, of course
  7. The ftdi chipsets assign themselves a com number on first plugin. After that, it matters not which usb socket you connect to, it will retain the port number (unless you want to change it). The improved reliability over the prolific chips is like night and day!
  8. Ad-blocker is your friend Although I may have a go at making a Pi-hole soon: https://pi-hole.net/
  9. You could always lend it to another local astronomer who would benefit from it.
  10. Your scope is a reflector = no chromatic aberration (CA). The (cheap) barlow has at least one refracting lens = possibility of CA. 99.5% it's the barlow.
  11. East-West is almost Up-Down in you image. As the (very wiggly) star trails in your image are neither vertical or horizontal, I'd say it was a balance/weight/gear slipping/bearing issue. So it is not the RA tracking. The movement is largely in the East-West direction, so my guess is that the DEC axis was continually slipping in little increments, and then these movements were enough to also upset the RA tracking somewhat. This also fits in with the Pleiades tracking OK, as the more vertical the scope gets, the lower the turning moment it produces on the DEC axis. Balance again and make sure that the clutch is done up a wee bit tighter next time, and see what happens.
  12. Great idea, I will borrow it. Of course the total eclipses will take priority!
  13. I do believe that you have imaged the Solarians mass transit system! Seriously, that is absolutely brilliant!
  14. If it doesn't cost you anything/much to try - why not have a go? I think your limitation might be with your mount - what one is it? Also, I think that @Stub Mandrel has probably done what you are suggesting - and he will know everywhere it could go wrong!
  15. Super! What's all that black tape doing? I hope it's just a low voltage cable!!
  16. Agreed! There is so much negativity and hate going on online. This is a smashing haven for the sane and well-meaning.
  17. Are you using the correct bahtinov mask for the new focal ratio? It can make a difference.
  18. I have an Esprit ed80 too. I'm afraid that there is no way to get the oag and the fw behind the flattener without exceeing the back-focus distance of 55 mm. As for tuning the spacing, some imagers luck out with the exact recommended 55 mm, but i didn't! Two years on and i stil haven't got it perfect, but it is "good enough"
  19. Star registration will do a <ahem> stellar job of this.
  20. I stretched the astrobin image out over nearly three monitors! It's a brilliant image. When you get it printed, make sure to find someone who will help you get the best results.
  21. Marvelous! You should put that wall on your wall!
  22. That's great. I'd better get up to speed with my processing. I've got no more excuses!
  23. I tried the tsred279 on my Esprit 80ed, which was "supposed" to work with the matching adaptor. However, by the time I had the backfocus getting to the right place, it wasn't possible to wind the draw tube far enough in to get focus! Shame, because the additional fov it was giving me made a heck of a difference!
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