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  2. Hi, I'm a newbie and I've used a fair amount of hours on the web studying polar alignment now. I thought i had it after 30 minutes, but now several hours later i understand less than i did then. I have the EQ5-mount and the "new" sky-watcher polar alignment reticule, which represents a clock, but no Northern hemisphere constallations. I get the Polaris position from an app. It gives me a visual position in the clockwheel simular to the one in my polar scope. It also displays the Polaris position digitally (i.e. 01:37, which corresponds to the visual position on the clock). It gives me my local longitude (5* 15'E). Lastly it gives me the local time. From what i understand the "old" Polar reticules doesn't have the clock, but a small dot or circle on the bigger circle with constallations around it like the big dipper that you align visually with the actual big dipper, then align Polaris in the small circle? 1. The Polar alignment scope i have has a white marker line on it (Index marker ring). What do i use this for, and should it point in the 12'oclock position or do i turn on this at some time? 2. When i rotate the RA axis, the polar clock also rotate. Are the 6 o'clock position always supposed to point straight down, and 12 o'clock position always supposed to point straight up when i polar align or do i have to rotate the clock in relation to my position (longitude) or something? Like, do i have to calibrate the clockwheel orientation at any time to get accurate alignment or does always 6 point straight down like an actual clock? I dont mean calibrating to make the reticule calibrated by this, but turning around the clock reticule so that 6 o'clock is no longer in the 6 o'clock position. 3. Do i have to take in consideration that the view in the polar alignment scope is upside-down, or do i Place polaris identically like on the app? (SAM console is the app, and i downloaded it for my Sky-watcher adventurer mini). 4. The videos and articles i've read on this type of reticle also provides you a HA (Hour angle). Is the new reticle just a clock showing this HA? Or do I have to take HA in consideration in addition to aligning or is this polar clock really just showing the HA visually? 5. Some articles (this for instance: https://lonewolfonline.net/polar-alignment-equatorial-telescope-mount/ says that its important to know what date and time of the year the Polaris is at its highest altitude. Why is this important? 6. Videos and articles mentions that putting my telescope in "Home position" is important. Why is this? The polar alignment Scope is pointing the same way no matter where the telescope points. 7. As mentioned the app provides my local longitude. Is this important in the alignment process other than "Nice to know"? I welcome any answers!
  3. Been watching a science programme on BBC4 which mentioned the Challenger Shuttle accident and the cause, which turned out to be freezing cold weather affecting rubber O rings. Now I wonder if frost was the reason my ASC seals failed. Bathroom sealant is used at room temperature and not designed for large temperature range, particularly cold.
  4. And tonights winner is Sky Safari, just been trying to get a few snaps of Pallas between the clouds and SS is spot on, Stellarium way off. Dave
  5. Can't help you as I don't have one either. I was told that the Samyang with golden Ring should be avoided and the new ones with red Ring are better. The one I used was a borrowed sample of the latest version. Was ok. Fabio
  6. Anybody spot this ? bright slow and red heading east / west in area of Cassiopeia. Dave
  7. I'm so sorry for your experience but luckily the seller has been great! You probably just ran into a bad stock, which for sure speaks against Synta QC. I got my HEQ5 used and could test it before deciding to keep it, so was sure it was ok: it's belt modded now and exhibits 23arcsec Peak-peak Periodic Error and guides better than 0.6" on nights with good seeing. So you see it's hit and miss! Best of luck with your CEM25p. Fabio
  8. Hello and welcome! Given your location and viewing preferences I would definitely choose the 200p. Easy to handle and capable of fantastic views of the solar system as well as deep sky objects, you can't go wrong really.
  9. The black dot will appear if the eye is not in the correct distance from the lens. I have the same thing. I've not seen that the center is out of focus, so I guess you have better eyesight than me. When the light passes close to the edges of the mirror and veins it will be deflected, because of heisenbergs uncertaninty priciple. But its not many photons compared to the whole lot. And there will always be a shadow in the center off focus. But I have not noticed anything in focus during daylight testing.
  10. I've a 2.5x PM, and use it with my Pan24, N13T6 and N7T6. It works just beautifully: very happy with it - a lifetime purchase, like my TV EPs
  11. You want old fashioned glass grinding and polishing. Quite interesting what little they do show.
  12. Thank you for the explanation. I really need to try a zoom out. Every time I lug around my eyepiece sets I start to thinking about getting a zoom eyepiece. Maybe it is an excuse to buy yet another eyepiece.
  13. Ideally one would want average across the FOV. FWHM should not change much from star to star. It is pretty consistent measure. There are always slight variations due to noise and because blue part of spectrum gets scattered more in atmosphere and seeing influences it more, but values should be close. However, due to optical design and field curvature there is larger variation between central and outer regions (this is the way one can measure field curvature of particular scope). I guess best way for determining resolution would be to take average of stars in a crop around target area - much like larger rectangular area in your first image outlining region of interest. I don't use PI myself, but I'm certain I can find the right tool online, give me a sec ... Here it is, under DynamicPSF process, reference page: https://pixinsight.com/doc/tools/DynamicPSF/DynamicPSF.html Take gaussian profile of region of frame and look under FWHM column. There is probably option to get average value or something. If it's in pixels, we would need to convert it to arc seconds by use of imaging resolution.
  14. Hi there and thanks for the info. I thought that DSS was linear when saving the image out of the Stack and without post processing. I can't save the final image in StarTools as I don't have a licenced copy, but can't decide to purchase it as I'm not convinced it's the best choice for processing. I'll need to test Pixinsight in parallel on the same image, so I can decide.
  15. There'll be some dark jiggery-pokery involved somewhere. James
  16. johninderby

    OO-UK

    Yes they are. Orion Optics UK Lymedale Industrial Estate Brymbo Road Newcastle Under Lyme Staffordshire ST5 9HX
  17. What shape is it? Is it the same on both sides of focus? How much are you defocusing to see this? In a fast scope the secondary is offset away from the focuser. This offset is probably built into the secondary support so if you measure from the centre screw of the secondary to the walls of the OTA and get it centred it will probably be good enough. This sounds like you are defocusing enough to see the secondary shadow, which is too much. You should only be defocusing enough to see diffraction rings as far as I know.
  18. I'm near the 5 ways. I am leaning towards the 200p dob
  19. I don't know, to be honest. But I wonder what other commercial applications require grinding to the same level of accuracy. If you said you wanted 1/10th wave accuracy, that's going to be in the region of five ten thousandths of a millimetre, isn't it? Or have I missed something? James
  20. That's really nice. More colour than Dulux. It makes my efforts look quite dull ! That horizon looks very clean. Can I ask where it is ? Dave.
  21. Thats the best image i have ever seen on this forum. Outstanding. Mick.
  22. fozzybear

    OO-UK

    I thought as much had great help back in the day and recently also with the help from John at OO I take it they are still in Newcastle under Lyme….
  23. My other 2" Lunt wedge only has an ND3.0 filter installed so I thought this one should be ok to use with one screwed onto the eyepiece holder, I do have another Baader 2" ND filter but it has OD 1.8 printed on it but I don't fancy using that one.
  24. This may be sacrilege but watching the video it all seems so very old-fashioned. Surely nowadays there must be smarter robotic ways to grind perfect optical surfaces. Or what is so special about grinding glass compared to other surfaces?
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