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CraigT82

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Posts posted by CraigT82

  1. 3 hours ago, paulastro said:

      As my diseased hip got worse  ( I had it replaced with a new one on Jan 9th!) I too struggled with my 10inch SS Dob.  Quite by accident I came across the device below on FLOs website.  When I read about it, I was very doubtful  and so it did when it arrived - at first it just looked like a jumble of wide Velcro.

    However, it works extremely well, at least for me.  It works very well even if you just use the two straps, the harness round the neck makes it easier if you have to carry the scope any distance.  The harness bit can be detached by two clips when you have the scope in position.

    Screenshot_20230928_202638_SamsungInternet.thumb.jpg.431ce64cff6fa6c019101da83e53dbe6.jpg

    20231004_145616.thumb.jpg.97730ce21c8789c84cc22009e9f4bac2.jpg

    20231004_144807.thumb.jpg.78db99056d807656094f0ec8176e631f.jpg

     

    Excellent… think I’ll order one of them to aid the manhandling of my 300p. Thanks for posting 

    • Like 2
  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.

    IMG_0859.jpeg

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    • Like 6
  4. 5 minutes ago, John said:

    I've got the 130mm triplet refractor out and cooled. Super start to the observing session with a beautiful moon, steady seeing and interesting moon action at Jupiter 🙂

    Highlights so far are seeing the darker material "tyre tracks" running across the floor of the Messier crater (right hand one in this image) at 350x:

    image.png.63c0a16a4f5938debdfca6230824e92e.png

    And Europa's shadow transit with Ganymede and Europa itself in close attendance (Stellarium generated image):

    stellarium-001.jpeg.183b10016580a01555201d7b2d2a6aed.jpeg

    Much more to come, I'm sure 😁

     

    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)

    IMG_0768.png

    • Like 3
    • Thanks 4
  5. 11 minutes ago, bosun21 said:

    Isn’t that atmospheric dispersion as there should be no coma in the centre of the field? I’m just starting out with planetary imaging and still trying to get a grasp of it all.

    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 

    • Like 1
  6. 4 hours ago, bosun21 said:

    I don’t understand how collimating with the imaging train in place is correct. If you collimate the SCT perfectly without the train attached then attach it and have to adjust the collimation again you are surely knocking the scope out of its actual collimation point. My thinking says you should ensure that your train is not inducing any tilt and if it is rectify that instead of compensating for it by moving the scope out of its good collimation. Making the train all screw on fittings would be advisable.

    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.

    image.png.6ffb43d48812b33458de3f42b5c52722.png

     

     

     

     

    • Thanks 1
  7. 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. 

    • Like 1
  8. 5 hours ago, a6400 said:

    As for star collimation some people already told me you can’t fully trust it.

    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. 

    • Like 2
  9. 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

     

    image.png.c9a42346337295e87ef47e26c0542fe6.png

    • Like 1
  10. 36 minutes ago, John said:

    I'd be looking for more precision than that which is why I suggested testing / adjusting the laser over a 20 feet+ range. For an F/4.5 newtonian the collimation "sweet spot" is just 2mm in diameter at the focal plane.

     

    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

    • Like 2
  11. 41 minutes ago, IDM said:

    As another person trying to learn/improve my planetary imaging I have been following this thread with interest. I totally accept the comments made about the need for good seeing in order to get decent images (no argument). I also understand the high frame rate to try and see through the best seeing. So in my case I use an SellaLyra 8 inch classical cassegrain with a Zwo ASI224 so I use reduce my region of interest round a planet and can get frame rates up to about 180FPS.

    I also understand the need for good focus, and now use a DIY electronic focuser which helps. Thought I do find the focus on my scope seems soft in that small changes in focus don't seem to alter what appears on the screen. Though I suppose the issue might be the seeing making it difficult to totally nail the focus.

    What I think would be helpful for the experts are hints on tips on other elements needed to get the best from a scope camera system. How much should I worry about the histogram?

    I also notic ethe comments around attaching the end of a barlow direct to the camera to get 1.X magnification. My Celestron barlow doesn't come apart like that. Can someone suggest a half decent suitable barlow that can be used? 

    I also would love any helps or links to good guides on processing. I have watched so many You Tube videos which often say different things. some say use linked wavelets others say don't! It's very difficult to know what to do to improve and then I see some of the stunning images that others put out and I am left scratching my head as to what to do. Any help gratefully received.

    I think I noticed earlier in the thread that Mark was wondering if he needed a larger/better scope. This is something I also wonder about so am currently thinking of going to either 9 1/4 or 11 inch SCT, but I am concerned that I will still have the same problems as with the current setup. So as I said any comments or links to the best up to date information on squeezing the most out of my planetary imaging would be really gratefully received by me and indeed Mark might then be able to take on his 14 year old adversary 🙂.

    Thanks

    Ian 

    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.

    Star Image Collimation.PNG

    • Like 1
  12. 5 hours ago, a6400 said:

    Yes this is a much better approach.

    I don’t know how people test it by rotating in a focuser as there is always some movement sideways.

    I will try the „V” method again, the problem with the Badeer one is it’s awful irregular shape.

    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.

    • Like 1
  13. 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”.
     

     

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  14. 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.

     

  15. 2 minutes ago, a6400 said:

    I remember seeing the opposite a couple of times on other forums. Hmmm

    It's important for me that it's easy to collimate the laser itself also.

    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 

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