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Olsin

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About Olsin

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    Nebula

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    Jutland, Denmark
  1. I've often wondered why telescope manufacturers don't install these as standard. It would be such a small expense for them.
  2. Simply put, you won't see colour in any DSO's if you're just looking in the eyepiece. They will for the most appear as a greyish smudge mark against a dark background, if you can see them at all. Faint nebula and suchlike only really become apparent through astrophotography. Images like your profile picture are achieved by long exposure photography. This is NOT how they appear to a naked eye looking through a telescope eyepiece. Astrophotography can be a rather demanding discipline. I suggest you read through AP posts here and elsewhere to get an overview of the kit, techniques and the myriad problems/challenges you're likely to encounter.
  3. No, i got that. I was mainly referring to the potential difference in coordinates between center in finder=enter, center in EP=align. Centering a star in a 1x telrad could still leave it out of FOV in a 20mm EP at FL 2350mm. My thought was a wondering if large inconsistent discrepancies in a stars position between pressing enter and align on the handset, could mess up goto accuracy..
  4. I'm not that experienced yet and have only recently ironed out the quirks in my own setup routine. What does strike though is you using a telrad with an Evo 9.25 scope. You give no reference to a reducer so that's a long focal length you're working with. I've never used a telrad but i understand they are just 1x. Maybe i'm wrong but i don't really see how that combination of FL and finder could be anywhere near precise. I spent a lot of time aligning my 6x30 finder with my C8 and i can usually put a star about halfway from the middle to the edge of FOV in a 20mm EP. Never get it spot on though despite the apparent sync between finder and OTA....there's to much focal length. You have more FL with a finder that's only 1x. A miniscule variance in head/eye/telrad position could give you wildly varying error margins when you align first with finder then EP..........or not. i don't know. Just my thoughts. I'm sure i've read a rule of thumb that said telrads and red dot finders are fine for shorter FL scopes, not so much so for the longer. Alternatively, and again not that i have a huge understanding of it, but have you ruled out cone error?
  5. Plate solving

    Ah i see. So you plate solve to acquire a solid reference point in the sky that you can refer back to for imaging purposes. Point taken Geoff. Thanks guys..
  6. I keep seeing this expression written and talked about without really understanding what it is. So can anyone explain to me what plate solving is and how it increases imaging accuracy?
  7. Polar scope on AVX?

    Sorry Alan, i've only just noticed this. Yes you're absolutely correct. That badly thought through design bears all the hallmarks of a design team that didn't really give a toss. That amongst other things, is one of the reasons i'm reluctant to consider buying anything from Celestron again.. Why do you need to get new bolts made. Can't you simply swap them around as i mentioned to John? I can only say that even an "almost" aligned PA scope on my avx + c8 doesn't give me a satisfactory PA. ASPA always gets it tighter. I can now get 30 sec subs without star trails. With a f6.3 reducer attached i can push it a little higher. I was lucky if i could get 5 sec subs when i first started using ASPA. But that was before i understood the routine and didn't know to pick calibration stars as close to the area i wanted to image as possible. It's not really that bad once you've gotten used to it..
  8. Random imaging question..

    I've used an asi120mm on my C8 and i wasn't overly impressed although that could very well have been because of bad to middle of the road seeing.The incredily small FOV makes good seeing conditions critical if you want to get a good focus. It's always seems to be jumping all over the place everytime i look at it. You can use this FOV Calculator to check out any combination of scope/ep/camera FOV. Click on "visual" if you want scope/ep FOV and "image" if you want scope/camera FOV. https://astronomy.tools/calculators/field_of_view/
  9. Thanks a lot Michael, that's what i was hoping to hear
  10. Thanks Pete .. I've seen those types of finder bases but without ever actually seeing one in the flesh, it's hard to decided how solid and substantial they are. A 60mm finder/guider weighing in at around a kilo would only be supported by 2 screws. To my mind that seems to little and even though i'm not initially guiding with this scope, i may want to try it in the near future. I'd want the finder/guider to be planted solid on the OTA.
  11. I couldn't really imagine it being any other way Here's the latest offering i've come across..This scope gets good reviews too. http://www.365astronomy.com/365Astronomy-60mm-Compact-Deluxe-Finder-and-Guidescope-Kit-with-1.25-Non-Rotating-Helical-Focuser.html But i still don't really know how i'd mount it on my C8. Am i right in thinking that i need another bar similar to the one already mounted onto my OTA, that is fastened both at the front and rear OTA housing ... and then a finder base screwed onto that for mounting the finder/guider? As in another of these bars..
  12. Ok thanks for that. The Altair looks like a fine scope. If i could ignore the mismatch in colour coordination (my mount and OTA is black/orange), what type of finder base would i need to mount that onto my C8........although again looking closer, it appears that some kind of universal base is provided with the scope! I'm not sure it looks very stable though. Do you experience any flexure with yours?
  13. Thanks Michael..isn't that usually the case
  14. Thanks ... As i mentioned, AP and guiding isn't really my main concern atm. I happened on that 50mm finder/guider as i was looking for something that would give me as wide a FOV as possible when used with an asi120...although reading through the reviews on that finder guider page i linked to, i see someone mentions that because of the short focal range, he need to use a barlow with his asi120 ... not really sure what that means!
  15. Yes it does have a long focal length but i use a 0.63x reducer with it so that brings me down to 1250mm. It also sits on a AVX mount that i'm lead to believe can do sub pixel guiding. The link above mentions sub pixel guiding up to 1500mm so with the reducer i should be covered. Although to be fair, i'm not really so interested in AP/guiding. I'd just like to be able to use my asi120mm to try out Sharp Cap's polar align feature. I brought it a year ago and haven't really used it. The long focal length makes using that camera very challenging.
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