Guest Steve Posted May 5, 2012 Share Posted May 5, 2012 Hi, Why an off-axis end-cap DIY filter rather than a whole-aperture cover for an SCT? Any difference in what you see? Does the off-axis opening need to be circular? Or could you do, say, 2 openings??? Or an irregular shape? (Reason for question is that I have ordered an A4 piece of Baader solar film foe C9.25, which is obviously smaller than the aperture. But I have found details for making an off-axis assembly, but I was wondering what the options might be). Thanks Steve (n.b anyone actually seen the sun?) Link to comment Share on other sites More sharing options...
red dwalf Posted May 5, 2012 Share Posted May 5, 2012 not a diy solution Steve, but i bought one of these second hand for my 8" sct. http://www.365astronomy.com/celestron-solar-filter-cpc-925-cge-925-p-160.html they just screw onto the front of the scope the same as the Celestron covers do. my version works well, allowing me to see sun spots and so on. you won`t see any flares though with them as they only allow white light through, but you can see some gradients around sun spots. Link to comment Share on other sites More sharing options...
Guest Steve Posted May 5, 2012 Share Posted May 5, 2012 Found this: - it's the sort of thing I was thinking of: So although I can't cover the entire 9.25" aperture with A4, I can make 4 off-axis apertures to gather more light than a single off-axis device. Anyone tried this? I do like a bit of cutting-and-sticking! Now where did I put that sticky-back plastic? Link to comment Share on other sites More sharing options...
BAZ Posted May 6, 2012 Share Posted May 6, 2012 You don't need to have a large aperture, as the amount of light is great, compared to normal night time objects not counting the Moon. But you also benefit from the smaller aperture to focal length ratio, which increases contrast, and can help to sharpen your view. I made a white light filter for the 127 refractor, but stopped the aperture down to 70mm, this works fine. When you make the holes, just make sure that they clear the spider vanes, or it will interfere with the view. Try it with just one 3" or 4" hole, I think you will get a good result. Link to comment Share on other sites More sharing options...
Guest Steve Posted May 6, 2012 Share Posted May 6, 2012 OK, cool thanks - I'll try one and see how I get on. Assuming FLO ever get my order processed. I mean, they have had a WHOLE working day to process it, but it's not here yet. Waaaaaaaaaaah Link to comment Share on other sites More sharing options...
Guest Steve Posted May 14, 2012 Share Posted May 14, 2012 Decided to over-engineer a solar filter with my Baadar film. Nice thick cardboard, 2 pieces sandwiched with off-axis aperture cut in both, film inserted, and all glued. The edge is thick corrugated cardboard cut into a strip and creased along each corrugation to form ring. Duck tape to give durability and snug fit onto the OTA. I used a length of electrical flex duck-taped around the inside of the ring to form a ledge the sndwich section buts into. Now the over-engineering. For protection I have cut 2 thinner pieces of cardboard, again with a, slightly larger, aperture. These go top and bottom, and the idea is they can be rotated to protect the solar film when not in use. The final touch will be to go into the roof and dismantle one of the many clocks that my kids came home with from school over the years, so I can use the little brass dooflap that holds the hands in place to hold the protecting cardboard in place and make rotation easier! Bob is my uncle. Was away at the weekend, left the blleping thing at home by the front door, so didn't get chance to test it - just waiting for a sunny day! Link to comment Share on other sites More sharing options...
Guest Steve Posted May 14, 2012 Share Posted May 14, 2012 I will definitely want to do some images, and I guess solar could be first place to begin as I'll be able to see what I'm doing! Link to comment Share on other sites More sharing options...
Daz Type-R Posted May 14, 2012 Share Posted May 14, 2012 Cracking bit if D.i.y there - looks like a proper job! Nice one! Link to comment Share on other sites More sharing options...
Tweedledee Posted May 14, 2012 Share Posted May 14, 2012 Steve, The extra cardboard to twist round and protect the film both sides is an absolutely brilliant idea. Wish I'd thought of it! I have made cardboard/baader filters for various scopes and even binoculars, and always worried that the film might have got damaged between sessions. It only takes the tiniest pin prick and you won't be observing or even seeing anything more through that eye. Always worth holding the filter up towards the sun or bright sky and checking with the naked eye for pin pricks anyway, prior to putting it on the scope. Next time I make one, I will definitely incorporate the "Healey" safety feature. Nice scope and smart sun filter. Cheers, Pete. Link to comment Share on other sites More sharing options...
BAZ Posted May 14, 2012 Share Posted May 14, 2012 Very ingenious, excellent job Steve. Link to comment Share on other sites More sharing options...
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