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Showing results for tags 'f7'.
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Hi SLG gentlefolk, About 4 months ago I got into the process of ordering a custom made refractor - still an ongoing project and I thought I would share the experience with you Why a custom refractor? There is a certain kind of pleasure in getting something custom made for you, be it -I don't know - say cufflinks or a refractor. I certainly did not seriously plan to order one but randomness coalesced into a weird coincidence and that is exactly where I am now. This will be a rather long thread with a little bit posted every day as I am going through a lot of email exchanges (117 emails so far) to gather the pertinent parts and will document the built of a custom built refractor by Moonraker Telescopes UK . In retrospect, I can only say that it is truly my fault. How did I end up meeting Mark? Mark Turner is the man behind Moonraker Telescopes. The only "contact" I had with Moonraker was through Astrobuysell UK classifieds when once I clicked on the advertising banner link for Moonraker, checked the scopes really quick and said to myself "cracking scopes, not for me, let's move on". Moving on a few months down the line and specifically mid-July, I had a spare red Moonlite refractor focuser which I listed for sale on Astrobuysell UK classifieds and Mark needed said red focuser for a refractor built. I called him to discuss the focuser and we ended up chatting refractors, refractors and even more refractors. And that's when I decided I needed a custom refractor and to see how far down the proverbial rabbit hole I would go. Talking to Mark about scopes in general, I realized that I never actually fulfilled this unknown need of mine for something unique, despite trying refractors from 120mm down to 60mm (in 10mm increments), from Achro to ED and APO and never being fully satisfied. In the end, his insights transformed my initial vision to what I am happily sharing here. This is truly a labor of love and the sum total of significant effort to bring about this fine instrument, giving ultimate joy of looking through and also looking at the telescope. -
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.
