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I'm considering the 250PDS. The main use is visual, and the second is EAA (I currently use a zwo183mm).
What I'm hesitant about is the primary focus. since It's mostly for visual, I'm wondering on how much back focus it has compared to the standard Skywatcher 10" dobsonians? with the standard dobsonias with the same optics and focuser you already need an extension tube for most eyepieces...
Also, there's probably a "bigger" obstruction (bigger shadow on primary)?
Just wondering if anyone out there had upgraded their secondary spider to use one of these CNC secondary cells ? just looking for some feedback to see how much of a difference they make - primarily interested from a collimation perspective, but also interested to see how much it impacts your diffraction spikes.
Due to an unfortunate accident my SN10 primary mirror is broken. While it was an unwieldy beast and pretty much required a complete rebuild when I got it from the previous owner I really loved it.
My understanding, thanks to discussions between owners of this OTA, is that the SN10 used a spherical mirror. However Meade's representative did not wish to confirm this "proprietary information" after stating that they could not sell me a replacement.
So, I'm stuck with a bit of a quandary: do I roll the dice and attempt to get a spherical mirror constructed? (I doubt that non-parabolic mirrors are routinely manufactured and would probably come at a price-premium). I have read anecdotal discussions that the primaries are somehow "matched" to the schmitt correctors which, I must admit, makes no sense to me as I thought that a spherical mirror was manufactured with a uniform curvature. Thus, without more information, I'm thinking that this could be an expensive and ultimately unworkable solution.
Alternatively, do I cut my losses and replace it with something like a Skywatcher 250P?
Any other suggestions?
Many thanks for taking the time to read this and for any advice you can render.
Hi, I got a skywatcher skyliner 200p dobisonian a few days ago, my first observing session was out in the cold and the telescope dewed up when I bought it back in. I then noticed that the glass on the base of the telescope(not the primary mirror inside) was smudged and had a little ring shaped scratch on it. I tried cleaning with a lense cloth but it is still slightly dcratched and smudged. Does anyone know if this makes a difference to the inside primary mirror?
I'm collimating my Skywatcher 150p reflector and have got so far with aligning the secondary according to AstroBaby's guide, however I seem to be at a conflict with the positioning in the focuser tube. It looks to be aligned up/down the main tube, but not left/right (looking into the main tube from the open end) or up/down when looking down the focuser tube with a collimating cap on.
i was told to align the secondary to the middle using the spider vane adjustments, but I can't see any other way to move the mirror than to adjust the spider vanes, which would result in the secondary no longer being precisely central in the main tube. Am I missing something? I hope these photos explain it better. To my eyes there seems to be clearly a larger gap at the bottom than at the top.