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Darth Takahashi

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Posts posted by Darth Takahashi

  1. a ridiculously good performance from a scope costing £349 (from FLO, who supply them as OTA only.)

    You're going to enjoy this one, Luis.


    Excellent image, well done. Buying the scope second hand makes it an even better bargain!!! :grin: :grin: :grin: I just picked up an WO FD72 mint condition for only 250Euros!!! (Guide scope for the Tak's) :eek:

  2. Thanks again for the comments, I agree that some targets are better suited to hubble pallette irespective of the amount of Ha they contain (I once tried the flaming star nebula in narrowband,was not good :D ) Though narrowband lends it self better to my location due to the light pollution and poor skies.

    Nice image, almost as good as mine!!! :grin: but my location is worse that your!!! :tongue: Nice to see you back here posting images.

  3. Great work Martin, the second one is better, since its less stretch and showing less noise! A dark site would really help out a lot here. I spent some time at Mick's where he has mag. 6 sky's and it make a big difference. The sub's are noticeably smoother with a lot less noise etc...

    Never mind, one day I'm going to retire to a mountain top (at least 1500m) with perfect sky's and no light pollution... :grin: I might move in with Prokyon if he'll have me!!! :Envy:

  4. As you know well Martin, imaging with a focal length greater than 1500mm becomes very challenging for lots of reasons, the weather included! The native focal length of the Mewlon is 3000mm which is ideal for planetary imaging but not much else. The original reducer didn't really improve matters either, since it only brought the focal length down to 2500mm. The new corrector baffle already brings the focal length down to 2600mm, a shade over F10 while eliminating off axis coma and give 2 micron stars!!! But the real benefit comes with the new reducer, this take the Mewlon down to F7 or 1750mm focal length, this gives me a much more manageable scope and a very nice image scale for the smaller galaxy's etc...

    Take the reducer out and put a barlow in and you have a planetary telescope again... the new system makes it much more versatile overall.

    For my part, I have learn't to be a little more patient and to drift align on the pole which is mandatory at these focal lengths... Its a lot easier using short focal length refractors...

  5. I manage to get a few more hours of H Alpha on the bubble last night before the mist rolled in here in Holland. The weather conditions are making the transparency destinctly average at the moment, so unless I get some clear nights with exceptional transparency I'm calling it quits for now with the bubble.

    This image is now approximately 8.5 hours worth of data with 4.5 coming from H Alpha.

    Unfortunately, on the second image run I had some rotation between session, therefore, I have had to blend the two successive images together to create the final image that you see here. Can't wait to get my obsy finished.

    No flats used, thats not intentional, I just have no way at present to flat field such a large telescope... something for my Christmas list I think! :grin:


    I hope you like this image as much as I do. I'm very happy in that I now feel that I have a new telescope. I would never have dreamed of using the Mewlon in this manner before the modification. Can't wait to feed it some gallaxies in the spring!!!

  6. Very nice result, I too like the first image; I can't help feeling that the noise has increased slightly in the second image but that could be down the the stretch thats been applied?

    That also might explain the star colours!!!

  7. Winsorzied sigma clip needs to be set during the image integration in PI. You can find it under the pixel rejection tab...

    The optics definitely need to be looked at since as you know the stars aren't right at all and its very distracting in the image. The galaxy looks great and you are getting some nice detail coming through to the core.

    This just goes to show that extended object are very tolerant of optical issues but your not going to have any success with open cluster and globular clusters any time soon, well not until you solve the optical issue. If the scopes under warranty I'd take it back to the point of sale and ask them to fix it for you? If not and your not comfortable performing the necessary surgery on it yourself, try taking it to an astronomy club I'm sure someone can help you.

    (Per is right, it sounds stupid that the clip tightness can cause this issue with a thick primary mirror but it can! I have experience a similar issues with my own newt)

    Good luck

  8. Thanks for all the great comments; from another forum I had the comment that there is a little green haze lurking in the center of the image so I have run the SCNR function in Pixinsight to remove it, here is the result, I think you will agree that it has improved the image? The weather looks to be terrible next week so I don't know when I'm going to be able to finish it?


  9. Thanks for the info that's good advise. I tried 1/15sec last night but Jupiter was jumping around a little too much, therefore, I havent bothered to post the results, its just too soft. Seeing was poor!!!

    The good news is that 1/30sec is do able at max gain, I'll just have to get more frames to keep the noise in check. So what the maximum length I can image for without being affected by surface rotation? I thought its 3-4mins?

  10. This is the first such image from my Mewlon. As most may know I have struggled to use the Mewlon from my location, since it need excellent skys to get the most from it. However, I have spent a lot on this telescope and definately want to get more use under my skys with it, therefore, back in October 2012 I modified it with the new corrector baffle system designed to eliminate coma.

    The Mewlon is a Dall-kirham cassegain telescope and these have the best on axis optical performance; however, they do have off-axis coma inherrent in their design. The corrector baffle solves this issue and lowers the effective focal length, which is what I was interested in! With the baffle in place the focal ratio drops from F12 to F10, not much change there? But with the new focal reducer it drops to F7, just a little below 2m focal length and thats the change that I was looking for.

    This image of the Bubble is taken a F7 using the Mewlon. The coditions were average (Seeing & Transparency) and yet I was able to use the Mewlon!!!

    Its not all be pain sailing, I have also had to learn to drift align on the pole. To do this I use Metaguide since its also used to confirm that the collimation of the Mewlon is spot on. Metaguide is actually able to measure the drift and report back the new value after your adjustments, so you know very quickly if you are going in the wrong direction, which is great.

    Anyway the image capture was as follows;

    Red 8x300sec

    Blue 8x300sec

    Green 8x300sec

    Lum 8x300sec

    HA 10x600sec

    So about 4.5hours in total, probably I need another night to get the most from the image?

    Another important point is at the moment I cannot flat field the Mewlon, I need to build a light box!!! This would also improve the image quality eventually.

    I hope you like it? I'm very pleased with the results.


  11. Thanks for all the nice comments, I'm certainly very happy with the Celestron 2x Barlow, it's more than enough for me with the Mewlon. I noticed that it has a little thumb screw on it so I can probable more the camera back a little to increase the magnification?

    Also, next time I can lower the frame rate to 15 f/s to improve the sensitivity.

    Well let wait and see what happens on the next clear night, most probably that's weeks away!!!

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