Jump to content

sgl_imaging_challenge_banner_31.thumb.jpg.b7a41d6a0fa4e315f57ea3e240acf140.jpg

Recommended Posts

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.

post-3011-0-69800100-1353157580_thumb.jp

Edited by Darth Takahashi
Link to post
Share on other sites

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?

post-3011-0-91686300-1353229754_thumb.jp

Link to post
Share on other sites

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:

post-3011-0-64924600-1353354262_thumb.jp

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!!!

Link to post
Share on other sites

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...

Link to post
Share on other sites

A little more saturation with "Match Colour" and "Reduce Noise" with PhotoShop to smooth out the background a little more.

post-3011-0-62687300-1353438708_thumb.jp

Corrected the slight orange colour cast that I brought into the final image by accident...

Edited by Darth Takahashi
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Gerr
      The 6th January was clear and still and so at last a good night for imaging (not perfect as Moon was still waning).
      My 8" SW 200P Reflector was wanting to be used and so it was carefully mounted onto the HEQ5 and payload maxed out with the imaging train.
      Yeah I know - this combination is a big ask for the job (but an EQ6 is beyond me at the moment!). Anyway with careful balancing and hardly any wind it was worth trying!
      Nebula were best targets and again new ones for me.
      These were the Bubble Nebula, Cave Nebula and Monkey Head Nebula. The Optolong L-eNhance Dual Narrowband Filter was used for all images.
      Usual calibration frames and dithered instead of Dark's. Other 'Astro Stuff' is in my signature. 
      Any constructive criticism's welcome.
      Gerr
      Images:
      Bubble Nebula (Sharpless 162) 15x240secs (1 hour of data).
      Cave Nebula (Sh2-155) 7x240secs & 23x300secs (2hrs 23 mins).
      Monkey Head Nebula (NGC 2174) 44x240secs (just under 3hrs).
       
       
       



    • By cwinstone
      Hello, does anyone know if my imaging train looks correct, and if it does, why am i still getting these coma errors?
      Could it be incorrect backfocus? Searching the internet makes me think my dslr is 44mm, adding the t ring (even tried a 1mm spacer too) gets me to the required 55mm (assuming that's correct)
      I have no idea how to solve this and i feel like I'm just throwing money down the drain fighting this in vien. Help would be much appreciated.
      Skywacher Evostar 72ed
      Reducer rotator for 72ed (needs this for extra distance to achieve focus, the reducer and adapter alone doesn't allow for enough outwards travel)
      Reducer/corrector for ed72
      Canon eos 650d


    • By AstroM1
      Nikon D5100 + WO ZS73 II Star Adventurer Pro 150 x 30 sec + DOF
    • By SStanford
      Hi all,
      With the ongoing stock shortage it's going to be sometime before I get my hands on my desired scope for my ideal setup.
      I'd like to make the most of my current scope until stocks replenish and so I have a few questions about Flatteners and Reducers.
      I currently have a Celestron Inspire 100az (details here), a Canon 450D and a EQ3 Pro (synscan).
      As I understand, the 660mm focal length makes the scopes FOV too narrow for a mount such as the EQ3. Am I able to add a reducer to bring the focal length down to a level that would be suitable for this mount?
      If so, can someone provide some guidance as to which reducer would be the right choice?
      This brings me onto my next problem; I can achieve focus with my Canon 450D DSLR in the Celestron 100AZ but by only using the supplied diagonal (here) and my 2x Barlow (here).        
      I have tried using the 68mm extension tube that came with the T-ring and adaptor (here), inserting this directly into the scope but cannot achieve focus at all. In addition to a reducer, what else do i need to add to the OTA to get focussed?
      S.
    • By Gwil
      Hi Everyone,
      I've just bought a Skywatcher Evostar 72ed but can't get hold of the sky-watcher .85x reducer/flattener or the OVL versions in these current times.
      Can anyone suggest any alternatives to the above?
      Many thanks 
      John (UK)
       
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.