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AndyUK

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AndyUK last won the day on May 19 2013

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About AndyUK

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  1. For focusing, I know many simply open the lens up, ISO 25,600, zoom in 10x, centre a nice bright star and then bring it in and out of focus until happy that it's as good (small) as they can get it. However, I'm a great fan of bahtinov masks... There are 2 main types - Those that clip into the lens filter thread, and etched filters that slide into square filter holders. The clip in masks are a lot cheaper, but when I tried one I found the view using a 24mm lens (even f1.4 / ISO 25,600, live view 10x zoom) was too dim for me. There are also Y masks which might be brighter (but I've not tried one of those with a lens - Maybe someone else can comment?). I use an etched filter - There are two I know of - Lonely speck and Kase. Not cheap, and I have to admit I do struggle seeing the "whiskers" at 24mm, but it works pretty well at 70mm . (For framing I also have a hot-shoe mounted red-dot finder, but I've not used mine yet as I've only used 24mm and 70mm lenses so far...)
  2. AndyUK

    Moravian 8300

  3. Very nice indeed... and very good considering it was virtually full moon - You've got to love Astrodon NB filters for cutting through it! (I'm not sure what process you used for the Hubble Palette process, but I've always found this link quite a useful starting point...)
  4. The ED72 certainly does indeed seem to be an excellent little scope, and I'm sure it'll be perfect for its originally intended use (visual / solar on the SW Adventurer) but I've only managed to get it on the mount once since I've had it (just to give it a basic test - The intra / extra focus airey disks looked very good ). Unfortunately my skies aren't that great at all (my SQM reading is c. 17.9 ) and when I had a modded 40D I definitely had to use an LP filter, but I'm still encouraged to give it a go...
  5. Very nice indeed Mick . (I personally wouldn't have spotted the vignetting though....) I recently bought an ED72 myself for a "mobile" / SW adventurer setup, and am also getting a DSLR modded for milky way/night landscapes etc, but the more I see images like this the more I think it might be interesting to combine the OTA and the camera, put it on my AZ/EQ6 at home and see what comes out... . Do you use any kind of LP filter?
  6. I agree - These are seriously impressive results!
  7. It should do... 1. Select the imaging mode tab 2. Select a target [ie Messier - M31] 3. Select your telescope from the drop-down list (or custom scope and manually enter it - Focal length / aperture) 4. Select your camera from the drop-down list (or custom camera and manually enter it - Resolution / pixel size) 5. If you want to add a barlow or reducer, put that in the barlow option [Binning I usually leave at 1x1, ditto angle] 6. Click "add to view"... and M31 should be displayed (and you get all the calculations for focal ratio, resolution, field of view and Dawes limit) If you then go back and enter different values for step 3-5 and add that to view, you get 2 boxes showing the difference in field (and you can add more if you want :)) Here's an example of what you get:
  8. I had a similar problem... I first tried connecting my powered USB hub into a different laptop port (my laptop has 3 ports, although 2 share the same bus) but when that didn't work I plugged the camera directly into the laptop... and the images then completed downloading. (Unfortunately that wasn't the final solution for me as my USB hub was connected to my laptop inside the house via a 3m long active USB cable - I eventually bought a new powered hub, and that resolved the problem... Hopefully you won't have that problem!)
  9. Very informative indeed, Steve - I've learnt a lot from that (I'd better go and lie down now!). And a stunning image too - Thanks for the inspiration .
  10. I'll let you know... I can't say I can recall ever having seen a value of 0.00 when using Bahtinov Grabber (maybe it happened but I wasn't looking?!). I used to be very happy if I could achieve a focus error of +/- 10 microns (I'm not sure how that calculates but that would definitely be sub-pixel). It'll obviously be much easier with better transparency, and admittedly it's a little more difficult with narrowband filters. (I now have 3nm filters - that was the reason I decided to go for an auto-focuser!). If you wanted to practice with Bahtinov Grabber (to see if you like it), maybe try Luminance filter instead - The "whiskers" are MUCH easier to see and you can use shorter exposures .
  11. (Ah... If only I'd had a pound for every night I've had like that...!) The focus point with Bahtinov Grabber does shift between focus frames, but with careful tweaks you can usually get it fluctuating within the +/- critical focus point. You're right that tightening the focuser does have an impact though - It's a bit of a trial and error thing, but once you know roughly what the shift is, and which way, you can then then compensate. I know some people are very happy to focus on FWHM values and everyone has their own preference, but I just found Bahtinov grabber satisfied my OCD's when seeing the concentric rings appear on the screen
  12. I 100% agree with this! I always set myself a couple of aims for each testing session - If I achieve the first, it's a result. If I achieve both... (well, I'll let you know!). You might get a bit of a gradient, but for testing, any night without clouds will do . Silly question (and I don't want to teach you to suck eggs) but as you've mentioned focusing issues, can I ask how you focus? I used to use a Bahtinov mask with Bahtinov grabber (I think there's now something similar in APT?). If using a 7nm Ha filter, I used bin 3x3 and looped 10s exposures on a nice fat star (say Altair in your screenshot?). That usually pegged the focus down to within a few microns... (but then of course there were other potential gremlins to watch out for, namely guiding, spacing/tilt and drift/rotation - I could probably write a book on spacing/tilt and the evils of tilt adjusters!)
  13. Wow - What an incredible image... and so beautifully processed. Congratulations on such a superb result .
  14. Losmandy Plate now sold... I'm temporarily withdrawning the MN190 and I'll repost the Barlow separately
  15. As Olly said this is a really unusual image... and for me quite surprising - I can't recall seeing an image of a globular cluster surrounded by dust before. A superb image (and excellently processed ).
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