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About jambouk

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  1. History of eyepieces

    Following a talk last night on the use of colour filters in observational astronomy by Alan Heath at my local society, I looked for something on the history of eyepieces. I found this comprehensive document which does a pretty good job [and a detailed one] of working through the different groups of eyepieces there have been in the last hundred years or so. It's quite long, and there are lots of equations and the like, but these can be skipped over. I simply found this on the internet, I cannot take any credit for it. http://www.brayebrookobservatory.org/BrayObsWebSite/BOOKS/EVOLUTIONofEYEPIECES.pdf James
  2. Tolles eyepiece

    Looking for a Tolles eyepiece, ideally in the range of 9-10mm. Drop me a message if you have one you are happy to sell. James
  3. Mak to EOS

    I agree, which is why I want to not use 1.25" kit. But is there an adapter which goes from Mak visual back to T2? James
  4. Mak to EOS

    Is there an adapter which goes from a Mak visual back (SW 150 Mak) to T2 to allow an EOS DSLR with an "EOS to T2 ring" to attach directly, or is it best to get a Mak to 2" adapter (which we have) and just get a 2" nose piece for the EOS ring? I want to keep it all 2" and not 1.25". James
  5. Cometographia

    Another fascinating video. Thanks for sharing. James
  6. SHA e-news, August 2017

    Yes, it is fascinating to read about people of the past, and the equipment they cobbled together and the impressive results they achieved. Many of the notable amateurs from the past really did push forward the science community's understanding of the sky above us (and the earth beneath our feet). The SHA Bulletin will be out at the end of September and I am sure it will have plenty of interesting stuff in it again. I will be at the SHA Library in Birmingham on the 15th August, you should pop along sometime and have a browse or borrow some books. The opening schedule for the library is on the website. I hope you've also booked a place for the AGM in October also in Birmingham. Again information in e-News and on the website. James
  7. The August edition of the Society for the History of Astronomy's e-News is now available and accessible to all: https://societyforthehistoryofastronomy.com/the-e-news/ Lots of good stuff in there as usual, though I am biased being the SHA's Librarian The SHA is going to have a stand at the IAS in October and I'll be there selling books the library doesn't want to keep. Any boy there is a pile of books; I'm not sure how my poor little car is going to cope under the weight. James
  8. ed80 ds pro f7.5 speed

    I love these threads; poor Olly must be fed up of typing this stuff out every few weeks
  9. Can you show the polo mint on here? often focual reducers need to be carefully paired a specif telescope. Is this focal reducer designed for the C8? James
  10. SHA e-news May 2017

    The May edition of the Society for the History of Astronomy's e-News is now available and accessible to all: https://societyforthehistoryofastronomy.files.wordpress.com/2017/05/enews-2017-02.pdf James
  11. My First Moon Shot

    I don't think there is any need to ask us to go easy on you, you clearly have taken to this like a duck to water. I think carry on are you are. Your images have been taken at near full moon. You can't alter what phase the Moon is at. Imaging the Moon at full get a nice bright disc, but the sun shining directly onto the full face of the Moon bleaches most of the fine detail out other than the mare and the ray systems. If you want to pick up fine detail you have to image either side of the full moon, when the terminator, the line which seperates lunar daytime and lunar night, moves across the face of the Moon. Features near or on the terminator are exposed to sunlight coming in form a low angle, and this is when shadows appear and much finer detail can be determinded. Several books take the reader on what features to observe and image on what day of the lunar cycle. There is a pretty extensive list of nice lunar books in these two articles. Just keep at it, you are doing better than fine James https://britastro.org/node/9399 https://britastro.org/node/9279
  12. My first images

    Just check the software you are using does pick the best percentage of frames. If the seeing is good and many frames look stable, whack this up to20, 30, 40, 50, 60% - experiment; Damian Peach says try to get 2000 useable frames for the planets., so if you are starting with 4000, ideally use 50% of them, but clearly if 88% are AWFUL then this isn't to be advised. You should only use the FWHM algorithmon a pin point of light, so on a star, not on a planet or the Moon. It is a valid technique as a) there is a fair amount of scope for you to be within critical focus with your scope unlike other makes of telescope and b), I suspect infinity focus on a star is pretytclose to infinity focus on something in the solar system. Make sure you are picking a star at a similar altitude and in a similar part of the sky as your target object. Ahome made exlectric focuser can be a real help too. Lots of threads about these online. There is another guy from Vancouver on here, probably several others, hopefully you've all managed to network. Keep up the good work. James
  13. For vibration supression I'm not sure they are that useful. What mount are you using? What they are good for, and depends on which ones you get, is marking where to put your mount each time you set up. If you can stick them to the ground / lawn whatever thennext time you set up you can just plonk the tripod legs in the pads. That is handy. But you don't need fancy, expensive vibration pads for this. There are a range of things to use for this purpose. James

    It looks like this map has been updated so is now much more user-friendly: https://www.lightpollutionmap.info/#zoom=7&lat=6957215&lon=-65609&layers=0BTFFFFT

    I love surveys though find it hard to answer this one. All of the sky in my back garden is hindered by light pollution, but actually the sky quality meter gives ma a reading of 19 which isn't bad seeing as Nottingham City Centre is just 2km away. I think for a survey like this to be meaningful it needs to have some quantitative data; eg what is the limiting magnitude from your back garden looking north, looking east, looking south, looking west, looking at the zenith... what is the SQM reading pointing at the zenith... Good luck with the project. James