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pook

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Everything posted by pook

  1. Probably a shorter one to start with.. around 6-10mm. I can cope with my current SW 25mm, but the 10mm SW is truly rubbish.
  2. I'm looking at Televue EPs and I'm confused as to what to get. Naglers look good and everyone raves about them, but the Radian EPs seem good also. Radian seems to have greater eye relief, but Nagler wider field. I'm seriously torn between the two kinds here.
  3. I've almost decided to remove the mirror clips entirely, but am worried about the security of just using silicone to hold the primary. Would it be possible to use brackets like this? That's a side on view.
  4. Although I'm a hard core Nikon user for everything else, I'm starting to feel the lack of support for Nikon so far as Astronomy goes. I'm on the look out for a used 500D body just for astro work. I agree with the others. Canon is the weapon of choice.
  5. Thanks. It's an option I'm considering, or as I said.. building my own from bought parts (I don't have the time or patience for grinding mirrors).
  6. I've found this a couple of time now. I just go straight up from Arcturus until I see it.
  7. Any update on availability yet? Nearly summer and no sign of new kit
  8. With my polarscope, once calibrated (and they do need calibrating before use) I can get over 1 minute exposures without even being particularly **** about polar alignment. I just use Polar Finder to give me transit times, and roughly set it to where it is on the screen. Before I got the polar scope, even 30 second exposures were a mess. [edit] I wasn't swearing, i used the word "a n a l" in a perfectly acceptable context.
  9. Is there any real advantage to paying thousands for an astrograph? If I was to steadily upgrade my 6" newt would I not end up in the same place? Upgrade the focuser, fit a 1/12 mirror set, use a decent coma corrector etc. What will be the difference? Even the OO CT series don't come with a coma corrector and recommend you use the Baader one. You can even buy carbon fibre tubes now. If I slowly rebuild the scope this way, will I end up with something as good for considerably less outlay? EDIT I could even build a scope from component parts rather than upgrade this one. 8" carbon tube, 9 point cell, 1/12 wave mirrors, decent focuser etc.. Seems to come out a LOT cheaper than buying one ready made. I started thinking about this after reading about teh SGL member who made a planetary newt from a 150PL and a OO mirror set.
  10. That was a good buy! Well done!
  11. That just means no lens.. just the body. If you only plan on using it for astro work, that's what you want. If you want it for general use, you need a lens as well. Remember though, that unless you choose a SLR with a full size chip (same size as 35mm film) the 50mm lens will have an effective focal length of 85mm or so. The "50" is touted as the first ideal lens because it's fast, and offers a natural field of view similar to the eye. However, unless you have a full size chip, a 35mm lens is actually the "standard" focal length. Lack of live view is an inconvenience certainly, but not essential.
  12. Series 2 was rubbish though! All monsters and US TV style pap! Series one was deep and thoughtful. Sorry to hijack the thread.. Carry on! I'm alsp pleased I read this thread as I was just about to buy some Bob's Knobs.. not so sure I will now.
  13. How's the mirror held into the cell of your AG12?
  14. You can turn it off on mine. High ISO Noise Reduction. Just turn it off.
  15. So what exactly did OO do to solve this? Baffle around the edge? I'm sure I've seen a OO scope mirror, and I don't recall seeing a baffle.
  16. I put two layers of acetate in it. It's just about right. If you defocus the beam to a really wide one, it's perfect, and you still have the option to close it up a little if you need a little more light.
  17. 1/1000th is fast enough to stop almost anything.. running athletes, speeding cars, running animals.. it would even begin to register a bullet (although it would be far from sharp). A bit of mirror vibration would have no visible effect at all.
  18. Hmm... not sure that's good advice. To avoid camera shake you want the fastest speed possible and when shooting the moon, and that's incredibly easy. When shooting the moon, you should be around 125th or so ( usually shoot at 250th to bring out more highlight headroom on the histogram) @ ISO100 using prime focus on most scopes, so if you up the ISO to 400 you're at 1/500th. That's easily enough to mitigate any camera shake cause by the mirror and still slow enough ISO speed to get excellent quality on most DSLRs these days, especially the D90. How were you managing to shoot at 1/30th for the moon at prime focus? and furthermore, I'm baffled how you got from 1/30th to 10 seconds by fitting a polariser, as that's an 11 stop difference! Even at full polarising angle most polarisers will only lose 4 stops, and that's an extreme case during the day with the sun at 45 degrees to lens axis. Something doesn't stack up there. See the attached screengrab of my RAW file capture (Lightroom) ... look bottom right. Ignore the focal length and aperture... that's just because there was no "lens" attached. As you can see... I shot this at 1/1000th sec at ISO400 with the camera at prime focus on a SW150P, so I've no idea how you're managing to shoot at 1/30th!!
  19. Best red light torch? A decent D cell Mag lite... then go to an art supply shop and get a sheet of red acetate. Unscrew the front cap of the maglite.. cut a circle of acetate the right size.. insert... screw the end back on and there you go. A red Mag Lite. You can do the same with a AA cell Mag Lite too for a smaller, lighter version. You just can't beat a mag lite.
  20. Maybe exit pupil diameter comes into play with larger scopes... someone who knows more than me will be along shortly no doubt
  21. You'll always be able to get the scope to foul the legs of the tripod at some point with a EQ mount. If you can't target the object without hitting the legs, do a meridian flip (rotate RA to get the weights on the opposite side) then slew the scope the other way through dec.
  22. I can see no reason why a 1.25" filter would not work in any scope, of any aperture that uses a 1.25" eyepiece.
  23. I've been through this myself. I was using a home made colli cap to centre and set the secondary, then a barlowed laser to set the primary, and I was having teh same problem. When the laser read set, the secondary appeared to be offset in the drawtube. I received a proper cheshire eyepiece today, and reset the secondary with that.. then set the primary with a barlowed laser, and now it appears perfect. Lasers are useless at setting the secondary, and a home made collicap doesn't allow a narrow enough border around the secondary to accurately adjust rotation to set it to a perfect circle. The cheshire gives a secondary view that has a really, really thin border around the secondary (due to long drawtube extention) and this allows for very accurate rotation alignment of the secondary. It will be your secondary rotation out. you can line up the secondary and primary with a barlowed laser, but that's no guarantee that the secondary is lined up with the focus draw tube. Get a decent cheshire to set secondary, and then use a barlowed laser.
  24. I hope it's not a turned down edge, as that's a quality killer! Is there a test to see if this is the case? If that mirror is has a bad edge I'm damned well returning the scope for a refund! Others have the same scope, and don't have this problem, which has made me think it's not the clips. If it was, everyone with a SW150P would be having the same issues as I am.
  25. Hmm.. looking at it again, it's as if the clips are just shadowing, or blocking out something being reflected from the edge of the mirror, so if I removed the clips somehow, then instead of getting rid of the problem, it would instead just produce a complete hazy ring around the stars instead. It's almost as if there's something about the edge of my mirror that's wrong, and the clips are just hiding this defect, not the cause of it.... if that makes sense. How likely is it that my mirror is faulty, or badly figured at the edge?
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