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I am selling my Takahashi Mewlon 108B as I made a serious mistake – I started Electronically Assisted Astronomy and now I am after a flat field refractor. This Mewlon, being the B series, comes with the 7x50 Takahashi illuminated finderscope, factory front cover, factory dovetail and a 2” JMI motorized focuser which works both with or without power (you need to loosen up a tool-less screw to gain manual control). I purchased this scope from Italy and you can see an actual review of this particular scope here (Google translate is your friend): http://www.dark-star.it/astronomia-articoli-e-test/test-strumentali/takahashi-mewlon-180-b/ The ad from Cloudynights is here: https://www.cloudynights.com/classifieds/item/130008-takahashi-mewlon-180b/ The scope will be shipped in the original box, properly packed and the original case will be placed in a bigger box, again, properly packed, via courier service, fully insured with tracking. I tested the scope myself and there is no loss of illumination or mirror damage which would warrant a recoating of this scope any time soon. The photos I attach I took when I mounted the scope. For more photos, just see the ad above. I would be happy to part with it for £ 1,240 including shipping and delivery.
Well I had a fairly productive night under the stars despite the almost full moon! Started out learning some new techniques for my DSO imaging, drift alignment with Metaguide etc... and gathering data on M57 until the unscheduled clouds rolled in for a laughs!!! Went to bed and set the alarm for 03:00 this morning when Jupiter would be in position for an image run... Got straight into it with the ExtQ, then I decided to try to see if I could increase the amplification of the ExtQ by adding a short extension tube and guess what it worked... This morning I calculate that I had about 1.9x instead of the 1.6 times magnification and you can clearly see the diference in the image set attached below. All image runs were 2000 frame @ 30 frame / sec using Firecapture and the DMK21 USB camera. Also, I now have a Celestron Ultima 2x barlow on its way to me from the UK, so when I return from my business trip, weather gods permitting I can push the Mewlon harder. I hope yo like the set, everything has been processed in the normal manner. However, I'm going to have a play with A2!S this afternoon to see if I can make any improvement. Your tips / suggestions are welcome? PS it great imaging the planets, I can post the result the next day, with DSO I have to wait sometimes a month to complete the image!!!
Last time was the first usable, fairly clear night since my return from my business trip. I had the telescope out imaging 2x planetary DSO (M57 & NGC7662) and left everything running into the night waiting for Jupiter to clear my next door neighbours house. Everything was ready, the DMK21, IR_filter and my new, well second hand Celestron 2x Ultima barlow. I was a little worried about this test, since in the past I have been using my ExtQ 1.6x with the Mewlon which is of course a very high quality piece of kit from Takahashi. So what could I expect from a Celestron Ultima 2x barlow??? I'm very very impressed by the results so far, see for yourself! The image scale has benefited greatly, the brightness has decreased and I'm now at my camera's maximum sensitivity. Also, I have increased the frame capture to 5000 from 2000 previously. Transparency was average to poor but the seeing was excellent all night. I managed to get 3x runs in before the image faded away as the clouds rolled in. I'm very happy with the result and see it as another step forward in my planetary imaging. Right now I probably don't have the optimum setting that will change with more time and experience with this setup. I more sensitive camera maybe needed, perhaps for Christmas!!! I still can't quite believe the quality of this rather small compact barlow package, its excellent and I must thank "Neil Phillips" for the recommendation. My WO Barlow was sold long ago and despite its size 2" and 3xED optic element claims couldn't compete with this package from Celestron. I have never used a Televue barlow or powermate but if I were them I'd be buying these Celestron Ultima up and crushing them, since from a Price v Performance point of view I cannot see a Televue barlow / powermate being that much better, its just not possible!!!
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.
Last night I set everything up ready and expecting a full nights imaging. Unfortunately the weather gods intervened and in the end limited my testing to just 30mins of which I managed to gather 12mins of good data...! The weather conditions were horrible, intermittent clouds with the thin wispy stuff in between etc... Normally I wouldn't have set everything up but it was promising to be clear??? In the end it ever happend. So here is the first successful test at F10 with the new Mewlon (with corrector baffle assembly) I still have some minor guiding issues but I'm very pleased with the results above; the stars are greatly improved with no sign of coma at all. The coma was never that bad but it was noticeable at the corners even on the ST10 chip. I would say that these stars are as perfect as they can be, give the weather conditions. I now have a telescope that I can guide at 2500mm fl, 3000mm fl was impossible!!! Or too frustrating? It can image the smaller DSO with no coma and hence has become most versatile. (Not just a specialised planetary scope). The next test will be M1 the crab at F7 with the new reducer fitted, most probably after I return from my net business trip.
A big thank you to everyone who commented on my Onion ringing problem because its now solved , great! I think the decisive fact was the Gamma needed to be at 100 or greater. At approximately 02:30 I managed to get this set of Jupiter images using the modified Mewlon M250S (CR Baffle added) and the DMK21 with the correct settings!!! They are only mono, taken using and IR-Pass filter; one day I will invest in a manual filter wheel and the necessary RGB filters but for now I'm very happy with the results. Still need some advise; As anyone used Metaguide? I'm trying to use this for collimation of the scope? I have read the manual and I think collimation is bang-on but want to push to get that last bit of perfection!!! Problem was that the "red dot" was moving around too much. Very close to the centre of the star and not too far away but perhaps I could have got a better result with a better technique??? Anyway, I hope that you like the images Most probably seeing conditions were the limiting factor