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Carl M

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About Carl M

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    Star Forming
  • Birthday 12/04/94

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    Ramsey, Cambridge, England
  1. That's really helpful thanks! I wish I'd also collimated the primary with my laser when I was out there now to see if I got the same result as these two horsehead images show. All my other images have these same two additional spikes on bright stars when I was using the laser for collimation. Then it would have pretty much confirmed it to be the focuser intruding into the light path. It may also explain why the shadow of the secondary shifted when I collimated the primary using a defocused star while outward focusing, then when I defocused the star again using inward focusing it was out of collimation again. I don't think the angle means much. If you rotate the camera in the focuser the spider vane spikes will move position, but the additional spikes stay static. I diagnosed this while I was out there. Also, when I took the image with the spider spikes intersecting the additional spikes the additional ones were coming from the same axis as where the focuser was. I remember meddling with the vanes while I was out there because I thought it might have been them! Seems as though all aspects point to the focuser
  2. Hmm you are correct, not the secondary mirror itself. I pointed it down just the open end of the tube to the primary and still saw the pattern. If anything it seemed like the primary was too far up the tube as the mirror wasn't touching all of the locking screws, I'm not sure if having the primary too far up the tube would cause issues? I'm fairly positive that the focuser hasn't obstructed the light path before but will check again on next clear night. I've also had two additional star spikes like this before, I wonder if these issues are connected to the same problem? Close up it looks like there may be more than two additional spikes, they just happen to be closer together unlike the first image. Quite hard to tell. Spider vanes are measured and all the same length, last thing to check is for the bent spider vanes. Can't do much to check any changes until the some clear skies come along! Thanks for help once again.
  3. Thanks for the suggestions, rather worryingly I've found that these additional spikes are coming from the actual secondary mirror itself. I put my laser in and can see at the bottom of the telescope (on the primary) these same spikes appear. I thought it may be from the mirror being too tight, but I've loosened the collimation screws and the centre bolt but these same spikes are still apparent.
  4. Hi all, Last night seemed like a good night to try and get collimation of my Quattro 8s sorted once and for all (or so it seemed), but rather than sorting it I've opened up another can of worms! It was the first night where I'd completely ditch the laser for collimating the primary mirror and collimate on a star instead. So I pulled the star (Capella) out of focus and into the middle of the frame to get the concentric rings. The primary was not collimated because the secondary shadow was not centred. So I centred it and took a 30 sec exposure. What I got was a star with the 4 normal diffraction spikes, but on the same axis mirrored quadruple ones! I'm fairly sure nothing was intruding the light path as Capella was pretty much directly overhead. I've had a search around online and seen that extra diffraction spikes can come from twisted vanes but the effect never gave this many diffraction spikes. Other interesting thing to note was that when I moved the star out of focus again the secondary shadow had moved and was no longer central. But when I moved the focuser the other way to defocus the star on the other side of focus it was centred! Would that indicate a focuser that is not sitting square? Any help would be much appreciated! Thanks, Carl
  5. You have some nice detail coming through there despite conditions. Only criticism I can give is that it looks a little green, give it a run through Photoshop with Hasta La Vista Green plugin and it should sort it.
  6. Yes I agree it doesn't look like star trails. Looks like coma that is being exacerbated by a spacing issue. I'm sure I've seen something like this before when people are imaging through an eyepiece projection method.
  7. Don't give up hope on it just yet, when I modded my 1000D as part of my dissertation myself and my co-workers had to take it apart and put it back together probably close to 10 times...and that was with 3 different people. Initially there was no response at all when turning the camera on after modifying we called it a day and thought it was probably dead. Next morning we took it apart again and reseated all the ribbon cables again, and like magic, it just happened to work fine again. I'm still using it to this day and have had no technical problems with it at all. Did you mark the ribbon cables with a sharpie or anything of the like? That's one of the things we forgot to do, it seems the ribbon cables are a bit picky on how they want to be seated. Perhaps go back to it another day and do the complete teardown again and try reseating all the cables again? This was what I was recommended to do, and although that was what we had been doing all along we still tried it again the next day and managed to get it working. At least yours was showing some kind of life after modifying, ours was just dead; no error, lcd didn't come on, no led on..not great motivation to keep trying
  8. Neq6 will be fine, my C9.25 is piggybacked with an ST80 on an older style EQ6 and still rock steady. You then have the option to use guidescope or OAG if you choose to autoguide. Most people would swear by an OAG when guiding an SCT, but can initially be a bit fiddly with spacing and getting focus with both cameras. I'd also recommend using the 12dstring FOV calculator or similar if you haven't already, you may find that some DSO's you want to image in the future won't fit fully in the frame (M42, M33, Andromeda etc..), even with the reducer. Other than that SCT's are great for the smaller objects.
  9. Yes you can use a C8 for small planetary nebulas and smaller galaxies, but it also depends on how well you are mounted and how accurate your autoguiding (or lack of) is because of the longer focal length. How are you planning on mounting it?
  10. m78

    Not sure whether you have it activated in PHD2 but it should save and deposit a guide log .txt file somewhere on your computer. If you have the log you can open it with a log viewer and show the graph from there as well as RMS values I believe.
  11. Thanks Martin, I agree the original is a bit too red - can see it especially in the stars. I added a star mask and de-saturated it a little to turn down the redness of the stars while boosting the blue and reducing the red a bit for the rest of the image. Hopefully this is a slight improvement.
  12. Thanks for that, if it were to be collimation would rotating the camera around the focuser change the direction of the worse corner in the image? I imaged M42 on the same night and looking at the images from that it shows that the top left is still the worse corner? Got me thinking perhaps it's something to do with the t-ring/coma corrector not sitting square - maybe even the sensor itself since it was self modified.
  13. m78

    PA first and then do the goto alignment. How do you mean rough PA using guidescope? You should only be using the polarscope of your mount to do your polar alignment, ignore whether you can or can't see polaris in any of your telescopes. You are attaching the polemaster to your mount to do your PA and not your guidescope? I'm no expert when it comes to guiding, but I've read that tolerable RMS is dependant on the equipment you are using. In either case I would assume that the lower the RMS better. Here was what my graph looked like on a good night, it's not always as flat but RMS was low and the pictures I was getting from camera were not trailing. Perhaps someone with better guidng knowledge can chime in if I'm wrong Hope this helps.
  14. It's a lot easier to fit in the frame, I had no end of trouble trying to get the whole of M31 and it's companion in the entire FOV a while ago. Felt like I'd tried every degree of rotation around the focuser with the camera!
  15. m78

    By pointing accuracy do you mean for the goto alignment? You can use your camera if you can get the star in the middle of your LCD. I find it's much easier to use a high power eyepiece to center the star then add the camera later. On the final star of the alignment attach the camera and use the star also for focus. Then you've finished the alignment as well as sorting focus for your camera ready for when you want to slew to your target. Your stars still do seem to be eggy, how is your guiding graph looking and RMS values? Since SCT has pretty long focal length any guiding or polar alignment glitches will really show up. Try and spend a night trying to get your guiding and polar alignment down to a T, it will really help a lot on future outings.