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CraigT82

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Everything posted by CraigT82

  1. Excellent… think I’ll order one of them to aid the manhandling of my 300p. Thanks for posting
  2. Yes I have thought about boarding up the roof joists and insulating above but I have so much stuff stored in the rafters in need to find somewhere else for it all to live. I also get a lot of moisture coming through the single skin brick walls too so have bought a couple of tins of Thompsons water seal to paint onto the outside in the summer when they are dry to stop that moisture migrating through
  3. Having lived here for over a year now I have struggled with the moisture levels in my garage. Adding air bricks and soffit vents helped stop condensation forming on the cold surfaces within but it’s still very damp with mould forming on wood and textiles that are stored inside. Also now having finally got around to fitting the new mirror set to my 300p I was not going to let it live in this damp space! Hence the garage dry room was born! A few bits of wood screwed to the floor and walls and some cheap poly sheeting I’ve created a separate room within the garage where my Astro stuff is now stored along with the outdoor furniture cushions to stop them going mouldy too. inside I’ve got a desiccant humidifier which keeps it under 50% humidity for minimal running costs of around 20p per day over the last few days. However that should go down as everything inside and the walls dry out and it no longer has to work as hard.
  4. Tomorrow at 6pm ish the moon and Jupiter will be 2 degrees apart, will be a nice sight in a low power EP. Weather looking good currently (for Somerset at least)
  5. Do you have the counterweight for that mount? It’s a 25kg payload limit with that so you’d be fine.
  6. Now available to download. Early beta version https://www.autostakkert.com/wp/download/
  7. No, atmospheric dispersion is obvious in any image usually, It’s also directionally consistent with blue shifted upwards towards the zenith, and red shifted downwards towards the horizon. This image above wasn’t exactly in the centre of the field so coma is smudging the light to one side, as indicated by the spilling light to the 4 o’clock direction
  8. Think about collimation simply as the act of making sure the centre of your primary mirror's optical axis is landing on the centre of your camera chip. The centre of the primary mirrors optical axis is where the image is sharpest and coma free (i.e. the "sweet spot" or "on axis"). The faster the mirror the smaller this coma free zone is. SCTs have very fast primary mirrors and so are sensitive to collimation despite the long overall focal length, On an SCT all you can do is twiddle the secondary mirror screws, which in effect steer the direction that the primary mirror is pointing - think of the optical axis of the primary mirror as a long thin stick protruding from the centre of the mirror - So you want to make this stick point right to the centre of your camera sensor. If you collimate the scope with juts an eyepiece in the back, great the view through that eyepiece will be 'on axis' and sharp. However if you then remove the eyepiece and add a heavy imaging train the camera sensor will most likely not be intercepting the 'stick' right in the middle of the sensor, if at all, and that's because of droop or sag from the weight of the imaging train (not to mention large focus changes - moving the mirror). So effectively you now need to recollimate the scope so that the stick is again pointing right to the middle of the camera sensor. If you didn't re-collimate and you go ahead and start imaging, the camera sensor will be capturing images which are off axis or out of the sweet spot, and will be affected by coma which will reduce the sharpness of the resulting image. This can be seen in planetary images if you crank up the levels - you can see a faint kind of halo effect which is the captured light being smeared to one side by the coma (red arrows). In this example, which is only a slight miscollimation, the user would need to use the collimation screws to move the image to the upper left on the chip (green arrow), to bring it back into the sweet spot where there is no coma.
  9. Filter wheels are generally used with monochrome cameras - I say generally because there are people who use them with colour cameras and various dual/tri band filters - but for the majority it’s with mono cameras. if you’re using a DSLR to image with then you wouldn’t need a filter wheel, unless it’s had the bayer matrix scrubbed and is mono? For a 5 slot wheel you could have RGB and L and one spare for Ha maybe. A 7 filter wheel lets you have RGB plus L and Ha, O3 and S2. In terms of the filter sizes, you can get away with 1.25” (31.75mm) up to about 4/3 sized sensors just about. Bigger sensors will need bigger filters.
  10. I’m not sure who would have told you that and why, but it really is the only method you can trust. It does take more time and can be difficult or impossible to do in rough seeing but then again in those conditions a slight miss-collimation isn’t going to ruin your views any more than the seeing is. Also as John mentions above you could even just do it once in order to validate your other methods so you know they produce good results and can trust them.
  11. This is a mono camera? I wonder if AS3 is trying to debayer it because it's not recognising it as a mono image? When you load up the video in AS3 do you get this status square which is telling you the bayer pattern it's detecting? If so then it's likely miss-identifying your mono camera as a colour camera, you can go into the colour menu and set it to mono
  12. Nice! Is the 125mm a big jump up visually from the 102?
  13. Interestingly Lego bricks also makes for very good V blocks, they’re made to a high precision dimensionally (0.005mm I think)
  14. Nice report Magnus, the 10mm BCO is a real peach, even at twice the price. Great deep sky eyepiece too.
  15. Yes I'd agree that V blocks would be more precise, however I'd counter that by saying that precision is not necessarily required, as any collimation method that involves clamping a device in your focuser will only get you close as there are too many uncontrolled variables. e.g. is the geometric centre of your mirror coincident with the optical centre, does your focuser clamp your eyepieces in the exact same way as your collimation device and is that repeatable and consistent etc etc... For a true collimation the only method that eliminate those variables is to do it on a star, but granted that has it's own issues
  16. Something to check on is your collimation. With any cassegrain system with a fast parabolic primary the collimation is going to be sensitive -even a small amount of miss-collimation could ruin high resolution images. The best way to collimate is to capture an video of a star through your complete imaging train (Barlow, filters, ADC etc...), and stack/sharpen it (same way as any planetary image). What you want to inspect is the first diffraction ring and how complete it is (see image below). If the ring is complete and even all around the collimation is good. If the ring is bunched up to one side then collimation is off. Use the collimation screws to move the star in the opposite direction to the bunching, and shoot a new video to check. Repeat until the ring is even and complete. Best to do this on a star that is close in the sky to your imaging target.
  17. You don’t need V blocks just to check the laser. With it in the focuser just unclamp the laser, turn it 180 degrees and reclamp it and see if the dot has moved which would tell you the laser collimation is out (or your focuser is rubbish). If it is out you will need V blocks and paper on the wall to recollimate it.
  18. Fascinating technique… never seen anything like that 👍🏼👍🏼👍🏼
  19. Beautiful shots Mike. For me the colour capture just has more zing to it, more ‘life’ if that makes sense?? The mono just looks a bit grey and dull in comparison (still a grey image though!) Zooming in to the e details and there not much between them really, the mono might look a bit more detailed due to the illumination but I think it’s actually neck and neck. I also have the 485c sensor and I like it a lot though not quite as fast in terms of FPS as the 462c I used to have. Need to try it on the moon once I’ve got my new mirrors in the 12”.
  20. One I made…. You can look up your intended focal ratio and see what pixel size you can use for that. For colour imaging I’d probably go with the green column Planetary%20Imaging%20Sampling%20Calculator 2.xlsx
  21. As Nik says any surface that can ‘see’ the sky is going to radiate its heat away and become colder than the ambient air temp and eventually below the dew point temp, This is when the dew forms on those surfaces. When I set up early and then leave it I’ll usually throw a large beach towel or tarp over it all, helps to prevent this radiated heat loss to the sky.
  22. Have you checked the Svbony and Baader units you have? Just rotate them in the focuser and see if the dot wanders on the primary. I think a laser is going to be the best option for you to collimate both primary and secondary on the dark
  23. Usually just shining a torch on the angled face of the Cheshire a enough. That reflects enough light down the tube to do the job
  24. I’ve just remembered the ES ultralight dobs are primary collimated from the front and can be done whilst looking through the eyepiece? If that’s the case I’d stick with the simple Cheshire sight tube and shine a light down at night. Do you need to collimate the secondary each time you set up? That’s a bit trickier to do on the dark.
  25. The last image in your post shows all the stars with coma and all pointing to the bottom left, so I’d say collimation is off and the sweet spot is off to the bottom left somewhere
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