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About JohnSadlerAstro

  • Rank
    Proto Star
  • Birthday 29/07/2001

Profile Information

  • Gender
  • Interests
    Astronomy, Aircraft, Aviation Gaming, Physics, Technology, RC Aviation, and Model Making
  • Location
    Chippenham, Wiltshire
  1. Imaging with the 130pds

    Creepy. I find collimation a frightening and nerve-wracking experience, despite the fact that ive read plenty of guides on how to do it. Last time I collimated (after taking the scope apart for putting black felt inside), I ended up going round in circles with aligning the secondary dead-centre and then being forced to tilt toe primary so much it was almost falling out of the tube! In the end, I got the right angle with the secondary and it seemed to work. I did cheat just a little tiny bit though --I slightly adjusted the secondary vanes to bring the secondary into the centre. Only by about 1 mm, I decided to get a compromise between the mirror being centred and the secondary being true to the focuser. John
  2. Imaging with the 130pds

    Hi, Surely there aren't actually any *actively negative* consequences? I mean, the telescope's resolution will continue the same regardless of how many camera pixels its image falls onto? So in theory, the only downsides are secondary, things like hotter camera (more pixels, probably less efficient cooling p/p) and also far larger file size per mm^2 of sensor? John
  3. Rubbish Chain, Rubbish sky

    Well, you certainly did better than me: I got stumped by connection issues before id even done the drift alignment! This season has been dreadful, hopefully next year will bring some better skies! John
  4. Three Moon landscapes 2018.04.22

    wow. wow. wow. This is probably a stupid question (as usual! ) but does the moon look anything like that through the same scope when just viewing visually? I've always wondered how clear large, posh scopes make lunar landscapes. John
  5. Firecapture Autoguiding

    Hi, I have to use the camera ST4 and Handset ports for guiding, and when those parts aren't broken (which they are atm ) I can get very consistent results. This is probably a side issue, but will your mount take a wedge? It would simplify the guiding and tracking a lot. John
  6. Hi, That looks like a good quality capture. . I would definitely recommend getting PA sorted out, then try some different sub lengths? You will be able to work out the best balance between tracking quality and exposure from there. When it comes around again, go for the Andromeda Galaxy! That will give a very satisfying image even with 30 second exposures. John
  7. RA Motor Guiding Issue

    Hi, Thinking about it, as Venus will be up this evening, I could try an extremely rough polar alignment and then try to get guiding on the planet as it becomes visible shortly after sunset. (We have rain starting around 8 o clock) Although PHD wont be able to guide properly, it should show up whether changing the ST4 cable makes the motor respond to the program? Do you reckon this will work? John
  8. RA Motor Guiding Issue

    Hi, I am tracking with Northern Hemisphere, that was one of the first things I checked when things started going wrong. Yes, the mount is set to 0.5 times sidereal, the other options are 16 and 2 times, neither of which are particularly suited to guiding from what ive found. I do have a spare "ST4" cable from an old Ethernet-phone cable adapter thing, I could try using that. However, as you say the fact that the pulses are reaching the light not the motor could be a fault in the "box" not the cable. P.S. the ST4 cable I'm using right now is the one which came with the ASI guidecam, so its unlikely there is an issue there. I have been using this setup for almost a year, and as far as i can remember the problems started around the new year. John
  9. RA Motor Guiding Issue

    Hi, Last night I was planning to get some data on the Whirlpool Galaxy, and I decided to use the PHD 2 Drift Align tool to get everything set up the EQ5. Unfortunately, there seems to be a serious issue with PHD's communication with the RA motor. The Right Ascension motor tracks at the correct speed and without any odd noises while guiding is not happening, but when PHD sends a guide pulse to it, nothing happens, and the motor seems to stop or run erratically without any obedience to the program's commands. Essentially, it ends up with something like this; with the RA motor speed remaining at 0.00 or dropping from around 0.12 to 0.00. Although the image below shows about 20 seconds of the issue, I have run like it for around a minute to see if the motor picked up, and it didn't. Once or twice, I did manage to get the guiding working fine, with health oscillation speeds of around 0.20-0.30; but these occasions were very rare. I've thought through the problem, and these are the things I know aren't causing issues: 1. PHD is communicating with the mount properly. I know this for 2 reasons. a) The green light on the motor handset blinks on every time PHD sends a guide pulse, showing it is reaching the handset. b ) Manual guide works *half* of the time, once backlash has cleared, indicating connection. 2. The power source makes no difference. I tried the rechargeable D cells as well as a mains adapter, and the issue remained the same. 3. The handset buttons still communicate fine with the motors. 4. The guidecam (ZWO ASI) is working fine, images are coming through at ordinary speed from it. 5. The cables all appear to be working fine and are properly connected. The best conclusion I can reach is that somewhere between the ST4 port and motor cable ports in the handset there must be a loose connection or damaged/dysfunctional part. Guide pulse signals are reaching the handset, yet the motors don't react unless the handset buttons are pressed. For some reason, the manual guide tool seems to be more successful in making the motors jump than the computer guiding; I don't understand how at all. I am not entirely sure if Dec is affected, but so far the main issue seems to be RA. A side issue, which may be related to this, occurred a few days ago. I was trying to get an image of the sun perfectly centred in the FOV, and I was using the +16x motor adjustment speed on the handset. Occasionally, when I pressed the button for a smaller adjustment, the motor would lag and then continue to run for around 10 seconds, throwing the sun right out of the view in some cases. This is a quick diagram I made, it should explain the setup. John
  10. need help

    Great! It's amazing how large the difference in focus between even far-away objects can be with a telescope! I hope you can get some clear skies for trying it out at night.... John
  11. Another go with a coloured moon

    Hi, Wow that looks amazing! How do you stop false colour (blue at the top and red at the bottom) from appearing? Just very expensive optics? John
  12. Flat Earth one line debunks

    On the subject of Christopher Columbus and the globe, I always laugh when people say he proved the earth was round. Actually, what he accomplished would have been just as easy on a flat earth--unfortunately North America was in the way of him proving the earth was round. I have heard it suggested that the "ignorance of the ancients" has been exaggerated in the last hundred years or so, possibly some of this came about through the Romanticised view of the middle ages in the mid 1800's?
  13. Flat Earth one line debunks

    Hi, This may be a slightly controversial view, but hey, this thread is for fun! Perhaps the reason why there isn't a specific one-liner is because there really is a big issue here--we all laugh at flat-earthers, but perhaps this really is dangerous ground. While completely keeping off politics, I has observed that social media seems to be able to spread very strange views, of which flat earth/aeroplane trails are prime examples! To me, the reason for this is because sensible debate never, or almost never, takes place in these platforms. I would really like to see a public debate between leading (but not the stuffy or big-headed sort ) scientists and leading flat earthers. A sensible courteous debate in which both sides can respond to each other and have some sensible dialog. Unfortunately, so many people on both sides of the debate seem to get angry far too quickly. If there's anything which will end this nonsense, an emotion-free debate in which flat-earth assertions are systematically disproved using everyday, observational science everyone can understand certainly will. My One-Liner is: Debate it! P.S. Well, the mod liked it, so it cant be all that controversial!
  14. Flat Earth one line debunks

    Well in that case, I wish it was! No need for polar alignment!
  15. Flat Earth one line debunks

    Not many, i reckon. Imagine putting that on your personal statement! "I was a member of the flat earth society for several years!" I noticed on the BBC a few days ago a vid of a guy who wants to see the world look round, so he is building a steam rocket. Unfortunately, his retired back (and weight! ) seemed to cause some issues when he landed. The rocket only got up to a coupla thousand feet anyway. He escaped serous injury but no golfing for a while.