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Subject: re: parabolic mirror on a meade ds-114 Sent: Monday, October 11, 2010 19:29:57 From: richard seymour (firstname.lastname@example.org) You can fairly easily -bend- the DS-114 mirror into a parabolic shape. In short, you glue a bolt to the back of the mirror (which gives you a threaded "handle"), and then rig something to allow you to "pull" on the bolt with a nut. Very little flexing is required. The focal length changes very little. Here are three Sky & Telescope articles describing the procedure (with photos): Nov 2000, p 131, Alan Alder "Flexing Spheres into High-Quality Telescope Mirrors" Feb 2001 "Flexing to Parabolize a Mirror" by Thomas Dobbins Nov 2003, p 138, "An Inexpensive Microflexed Newtonian Reflector" by Ernie Pfannenschmidt have fun --dick
Subject: parabolic mirror on a meade ds-114 Sent: Saturday, October 9, 2010 09:42:45 From: Maria Romo (email@example.com) I'm new to this hobby and am completely hooked. I know your time is limited so I'll be brief. My question is about the primary mirror on the meade ds-114EC. I was thinking about purchasing a parabolic primary to replace the spherical. I have already upgraded the eyepieces. Would this benefit this scope or am I wasting my time with this? I am aware that this is an entry level scope and would appreciate your knowledge in this matter. Also, would I have to change the secondary mirror if I was to change the primary? In a nutshell, is this scope set up for a mirror upgrade without doing a complete overhaul? Jason Goss & Maria RomoMike here: Swapping the primary mirror with a mirror of a different optical design and focal length will require more than just replacing the mirror. You will have to change the secondary mirror and likely its position as well to match the new mirror. Then you will need to re-collimate the telescope.
Thank you for replying. So it is possible then. The focal length part has me a little confused though. Are there more powerful mirrors than what comes standard on the ds 114? (parabolic) And will they collect more light?Mike here: Anything is possible. You may just have to cut new holes in the telescope tube, make your own mirror attachments, or perhaps even shorten or lengthen the telescope tube. Possibly lots of work. Have fun. A curved mirror focuses light at a certain distance from the mirror's surface. That's the focal length. How long that focal length is depends on the design of the mirror. It could be 400mm to several thousand millimeters. The eyepiece of the telescope then magnifies the focused image from the mirror, so the eyepiece has to be at the right distance. Larger mirrors will collect more light than smaller mirrors. The DS models come in different sizes. In fact, many telescope models come in difference sizes. Check the various telescope manufacturers web pages for more on their telescopes.
Thank you for the info. I think I understand the focal length now. If I got a mirror with a 400mm focal length I would have to shorten my tube being its set up now for 910mm(right?) I think that I'll just leave the existing mirror in there and start saving for an intermediate scope in the future. I would hate to ruin my first scope! Thanks again for your help, I believe you just saved me a lot of headaches!Mike here: Yep, the 400mm focal length mirror would have its focal plane well inside the telescope tube. Good decision to not try to swap the mirror.
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