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Northernlight

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About Northernlight

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  • Gender
    Male
  • Interests
    Ccd Imaging, Skiing, Diving, DIY Electronics, A nice cold beer on a hot day.
  • Location
    North
  1. Hi Pete, I have the 8" altair RC as well as a 102mm Doublet Refractor, so here's my take on it. 1) RC's do need a bit of patience to collimate, but as long as you take your time, it's not a particualry a hard process, but you will need to factor in the cost of some good colimation tools and I would recommend the addition of a focuser tilt Ring. 2) At F8, it's a slow optical design, so you're going to need longer Sub lengths if Imaging or possibly consider a reducer. I have a reducer, and have spaced mine to to give me a FL of around 1300mm @ F6, as it speeds it up a good bit whilst maintainging a fairly flat field and decent focal length. 3) Extra Focal Length = Harder to guide. So by the time you have purchased tilt rings, and possibly a reducer they start to get a bit more expensive. So if i could afford to replace my RC with someething else would i do it ? yes - probably , What would i get, Probably a larger refractor or maybe a high quality imaging newtonian at around the 1000mm FL mark. Rich.
  2. The hard bit now it trying to interprate what ccd inspector is showing me. Is that pink area due to primary or secondary, who knows. Guess I'll just have to try with trial and error.
  3. Still not 100% happy as there stars are now slightly elongated to the left side of the image, and looking at CCD inspector i can see that i'm slightly off, so i'll keep plugging away, but at least it show that the image is fairly flat.
  4. Well i managed to get a 15m break in the clouds so rushed to power up the obs and test RC again. I reduced the recommended 85mm spacing down to 75mm for the AP CCDT 667 reducer, which has added approx 100mm to the focal length. scope has went from approx 1050mm @ F5.3 to 1150mm f/l @ F5.75 so gained a bit of extra focal length and speed still acceptable, but now has now greatly improved the corners and reduced the vignetting significantly. Rich
  5. Hi Stu, 'not sure about the Tak, but I've read about other flourite doublets giving slightly red fringe to objects at higher magnifications, but on the plus side a good quality fluorite under most conditions will generally deliver a sharp image with slightly better contrast. i do agree about the larger aperture being handy. Rich
  6. Grumpy Martian, 'tell us your budget and your goals. Is it for visual, imaging or both ? Are you interested in wide, deep space or solar system ? If it was me, I would have to go with a scope around the 900-1000mm F/L, short enough to use a reducer for wide field, and long enough to use a Barlow for planetary / DSO work, so a good quality refractor fits the bill. dont have any experience of the Tak 100, but if it's a doublet, might be worth checking to make sure there aren't any colour aberrations when using visually and I'm certainly not qualified to discuss the merits of a fluorite doublet vs a triplet Apo. Rich.
  7. Hi Alan, on the MN190 focuser side of things, you can get a feather touch focuser with adapter that fits directly onto the Skywatcher base plate, no opening the tube or removing any base plates, literally swap out the Skywatcher focuser with the feather touch and the associated adapter and it's perfectly aligned, no faffing and no worries about positioning it correctly, just a direct swap. you can get them directly from FLO Rich.
  8. Thanks All, It's nice to make some progress with the RC as i was ready to throw it out of the window. One other factor that may have helped was that i completely stripped it down and rebuit it, which may have resolved issues like pinched optics etc. John, thanks for the heads up on the focal reducer spacing. I set it to exactly 85mm as that was the quoted spacing distance to use on the Teleskop Express website where i bought it from. On the next clear night, i'll reduce the spacing down maybe 5mm and see how i get on with that,whilst it would be slightly slower, i would welcome a little bit of extra focal length. I'll post another image after i reducing the spacing on the next clear night i get. Cheers, Rich.
  9. Well Olly, I gave the RC collimation one last bash last night whilst waiting for the clouds to clear. I gave my best effort with the Tak Scope, which when adding lots of extra lighting in the room was a lot easier to read. finally the clouds cleared enough at 2am to do some collimation testing. The conditoins were less than ideal as it was really murky, so i couldn't get the best focus. This was the best i could get with the Rc last night. it's not the best, but it's also not the worst and i'm attributing the slightly elongated stars at the edge being down to my AstroPhysics .667 Reducer. On the next clear night i'll try a test at the Native F8 and see if i still have the elongated stars or not, and if they still persist i'll pull the trigger on the MN190. Have a look and let me know your thoughts. Attached image was taken at F5.3 with the AstroPhysiscs .667 reducer and the FL was approx 1050mm. Please excuse the unprocessed single image taken through thick murky conditions, but at least it still gives an idea on the state of collimation. Rich.
  10. Grrrrrr, so sick of those BBC baboons, once again they forecast clear sky all night, and surprise surprise half way through collimating testing thick cloud cover rolls in. They couldn't get the weather right if their life depended upon it.
  11. Olly, a 12" newt is just too much of a big beast, the MN190 is the biggest wind sail I would want in my obs.
  12. Hi Ollly, It's funny you mention the F5 newt as I've I was just looking at the ONTC 8" F5 newt and whilst I'm sure it would be better mechanically, I just prefer the idea of the MN190 as it can be used visually and for imaging, and I love the idea of not having to use corrector. Teleskop Service ONTC 8" F5 Newt Rich.
  13. Hi Freddie, the feathertouch focuser bolts directly onto the Skywatcher base plate, so no need to open the tube :-) guess I'm just worried about mucking up the scope by opening it up.
  14. thanks Billy, you just made a very good point about the resolution and the fickle british weather, which i had never even considered. Which i guess renders the extra aperture almost irrelevant. This makes my decision a lot easier. Deep down in my heart i've always leaned towards to the MN190, as i like the idea of not needing any sort of corrector, which just means extra glass which can potentially fog up, which i have personally experienced. Going to Give my 8" RC one last try, and if i'm still not happy with it, i'll be dumping the RC and pulling the trriger on the MN190 with an upgraded feather touch focuser as it fit's directly into the skywatcher base plate without needing to open the scope up. Rich.
  15. Many Thanks olly, yet another facet to Imaging that I've learned today. So in simply terms, unless the object is filling your FOV you get diminishing returns when using a Reduer. So for i guess for me, If i'm happy with the Medium F/L of around 1m, then it's best going for a system that doesn't require a reducer, which ties in with me currently looking at MN190 or 10" Quattro, as both dont require reducers and are fast systems. Just can't make my mind up, plum for the larger apterture & Faster speed of the F4 Quattro, which is great for imaging, but not as good visually or go for the slightly slower & smaller aperture of the MN190 whichis good for both Imaging & visually. Who would think buying stuff could be so hard lol My heart is telling me the MN190 at the moment..... Rich.