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Trentend

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About Trentend

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    Nebula

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    Edinburgh
  1. Enjoying some great views of the moon this week through the VX12 on low power (binoviewers and 24mm panoptics). But still not as clear as hoped for on middle and higher power. When observing the moon at mid and high I notice if I move my eyes towards the bottom of the eyepiece and look up (rather than central looking straight ahead) the view is sharper. Does this suggest the secondary isn’t centred in the viewer correctly? Current position in the photo below. Also unable to properly resolve stars in the middle and high setting (but fine low). When I try and focus the top part of any star almost resolves clearly but a tail appears towards the bottom. A bit like a badminton shuttlecock pointing upwards (if that makes sense)? Have an ocs45 fitted so not sure if this is coma related (I don’t think it should). Cavalry arriving in the next week or so from the local Astronomy club to take a look, but any thoughts before then appreciated.
  2. In previous posts I mentioned hearing a slight rattle when moving/rolling my OO VX12. Wondered if something was loose in the scope (the mirror or the cell or both). Preferred not to take the scope apart so had a feel around in the space between the back of the mirror and the cell and turns out that 2 of the 3 arms (see red arrow in photo below, the parts with 3 white circular pads) are not flush to the back of the mirror and are moving a little. Is this normal, something I should try and fix (not sure if it’s adding to collimating issues?). What I don’t understand is the parts can be moved sideways around 5-10mm rather than up/down, ie closer to the mirror, almost suggesting one of the screws attaching the cell (in the picture below in yellow) isn’t there. Probably not describing that very well! Any thoughts? If I have to remove the cell is it easy to get back in?
  3. Any advice on the battery? Will only be using for the fan. Prefer something lightweight that will last around 4 hours in any 1 viewing.
  4. Appreciate all the feedback. Next steps are a) buy a battery for the fan (any recommendations given the cables in the picture above?), b) learn about the “star test” c) remember not to tighten the locking screws and d) gently roll the scope whilst in a horizontal position to see if there is something loose Regarding the 8inch skywatcher, I’ve never collimation this properly (other than with a cheap laser) but it’s always shown crystal clear views at medium and high power in the binoviewer and panoptics.
  5. Hmm, interesting point jam1e1. I recall before I received the mount a month ago and had a go collimating with the scope horizontal, I sensed a faint amount of movement in the primary when slowly rolling the tube but had forgotten about that. Pretty sure this wasn’t the mirror itself rotating, but the cell. I’ll have another look tomorrow. If there is movement, is it an easy job removing the primary and a fix? Apart from not touching the mirror, any advice while doing this? There’s plenty of dust on the mirror but I’m not sure I want to tackle that.
  6. I let the scope cool down for 3 hours last night, so hopefully that’s one less parameter out the equation. The full moon was pretty crisp and bright with the power switch on low magnification and 24mm in the binoviewer. The middle and high power though were very average and much better in the 8 inch skywatcher side by side, which I kept going back to. Appreciate the higher aperture increases the magnification (and presumably weakens the clarity like using a higher power ep?), but I just couldn’t get an especially clear/focused view. Not sure if this is collimation (likely) or sensitivity to atmospherics in a larger scope? There was noticeable wobble in the 12 and nothing in the 8. I will give the fan a try. What battery would people recommend for the cable connector I have in the picture below?
  7. After what seemed like an eternity (in reality just a couple of months!) a new dobsonian mount finally arrived from Orion Optics for my VX12. Took just a few minutes to build and a pretty accurate fit (not NASA standards and might need a little fettling in places but fine). This coincided nicely with a fullish moon and clear night so decided to set the scope up in the back garden next to my (soon to go) skywatcher explorer 200p for some side by side comparisons. Used my denkmeier binoviewer, powerswitch, ocs45 and panoptic 24mm in both. What I liked: The VX12 was so easy to set up. Just 30 seconds carrying the mount outside first (very easy to lift unlike the eq5 mount and weights) and the scope fitted very nicely on to this with no fuss. It really is a great design, very small footprint and will take seconds to transport and set up at local dark sights which was the main reason for the purchase. I also liked being seated at the scope (new to me!) and the scope movement in the mount was very smooth. What I didn’t like: Views of the moon in lowest power were good, but there was a lot of atmospheric wobble right out the box. Didn’t get any of this at low, medium or high power in the skywatcher. Guess that’s the difference in aperture and I’ll have to get more patient allowing for cool down? Views at medium and high power weren’t crisp at all. Despite collimating beforehand, using a Hotech laser (red dot seemed to be in the right places) there was some blurring and I found myself switching back to the skywatcher for better views. I guess it’s back to the drawing board with collimation. Could do better but not a bad start...
  8. Removed the secondary and surprised not to see a spring, just the central screw going straight in to back of the stalk. Should I fit one? Don’t think I have to but will a spring make the adjustments smoother? Also some interesting burr marks - the outer ones align to the current adjustment screws (now replaced with Bobs knobs, soooo much better). There are also some marks from what appears to have been adjustment screws much closer together! Not a problem as I’m going to cover these with a plastic washer (milk carton lid too small) but still odd!
  9. Bobs knobs arrive tomorrow to replace the existing 3 secondary adjusting screws in VX12. Wanting to add the milk bottle top mod while I’m at it. Will hold on to the secondary mount (but not touching the mirror) as I carefully unscrew the centre screw keeping the scope horizontal. Presume it’s easy to get the centre screw back on afterwards, being spring loaded, without any special tools?
  10. Also, are both of these to adjust the tension of the focuser (if so why two?). Apologies these are rather amateur question!!
  11. While I eagerly wait for a Cheshire to arrive next week so I can continue my collimating journey, I’ve been having a closer look at the focuser. I will definitely upgrade this as some point as it’s a little worse for wear (needs to hold a heavy denkmeier binoviewer, powerswitch, filter and eyepieces!). Can anyone tell me what the adjustments screws in the photo below are for?
  12. Ok, had a further fiddle this evening including loosening the central screw on the secondary and also making a minor adjustment to the vanes. Looks more centred this time around (first image below) compared to yesterday (bottom). Had a quick peak at the primary also. I can see two clips, the third is visible but not in front of the mirror, more within the tube. Cheshire ordered today and the journey continues..
  13. It was the secondary adjustment screws. I’d been applying a lot of force. Good to know I should stop and clearly something else misaligned. Any recommended links for adjusting the spider vanes?
  14. Thanks Martin, posted my reply to John just as your on advice came through. I’ll be doing visual only but looks like I need to adjust this. A related question, how tight should I tighten the screws on the secondary once I get back to that? Had the scope on it’s side applying quite a bit of pressure to get some movement.
  15. Thanks John, must admit I’ve read this a few times and still unclear in my mind if I try and adjust or just move on.
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