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About Astrofriend

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    Star Forming

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  1. Hi, Now I have finished the M1, M13, M31, M42 and M45. It's very interesting to study the details, remember these photos was taken when your grandfather was in action! /Lars
  2. Here is a project I have thought about over many years. What can I do with all scientific data that are out there? I tested this already 15 years ago with the POSS-I data from Mount Palomar observatory with good results. Now I'm just practising this how to handle the data and get something out of it. One easy task is just to make pictures from the data and compare it with my own photos. Just to get an idea how much worse my photos are compare to the telescopes at Mount Palomar. Here you can see how I have processed the first two Messier objects, M1 and M13: http://www.astrofriend.eu/astronomy/science-data/science-data.html Even more exiting is if I'm in the future can do some science with it. I have many cloudy nights so I'm desperate! /Lars
  3. Excel Astronomy calculations

    The last days has been productive, I have now transformed one more page of my Excel sheets, the Light Pollution calculator to a new Web Calculator page. I added a lot of new links with information, and also now tested that the calculation was correct, It at least look that now. You can read more here if you find it interesting: http://www.astrofriend.eu/astronomy/astronomy-calculations/skybackground-magnitude/sky-background-magnitude.html I now know that if I move from my balcony to a really dark place the sky background will be 5 magnitudes weaker or 1/100 of the flux. At the summer house I gain 3.6 magnitudes a typical night. /Lars
  4. Frustrating focuser problem

    Hi, I have a 3" focuser on my APO 5" telescope. High quality and works very fine, except it could slip sometimes in the friction coupling. Even if I set the force higher with the adjust screw it slip sometimes. When the telescope get wet from moisture the water act as an oilfilm and lubricate the axis and steel plate friction surfaces. Now I must do something about this problem, took the focuser apart yesterday and looked after what was wrong with it. I have as usual documented what I do, for myselfe and all other that maybe have the same problem: http://www.astrofriend.eu/astronomy/projects/project-focus-friction/project-focus-friction.html I will update the page when I have done the first test after my fix. Any smart ideas how to increase the friction? /Lars
  5. DIY, High efficient narrow band camera system

    Hi, It will catch three wavelength in parallel, one telescope, three cameras. Normally you only have one camera and one filter, then to get a rgb color from a mono chrome camera you have to take three exposures. Of course you can have three telescopes and three cameras als, then no need for a beam splitter. Normally when doing rgb photos with mono cameras you block 2/3 of the incomming photons. With other beamsplitters you can divide the incomming light in one visual and one IR beam. Then you need a mirror telescope. Some use the IR beam to autoguide on. Lars
  6. Excel Astronomy calculations

    Hi, Get correct focus is always tricky, sometimes the automatic focus function works, sometimes not. Not uncommon that I spend one hour to find the optimal focus point. Now I have done this excel sheet that could assist me. It's still in development process. I have added a new excel sheet, this one will calculate where the best focus is from a table of your focus positions and FWHM numbers. It fit a second degree polynomial to your numbers and find the focus point even if it's between your numbers. If you have temperature compensation activated it's better to deactivate it during this process. http://www.astrofriend.eu/astronomy/astronomy-calculations/excel-sheets/astronomy-calculations-excel.html /Lars
  7. Replacing a 2.5" flattener with a 3" flattener

    Hi, It was a long time ago since I wrote something about my 3" field flatter project. I have now done some tests and the results are wonderful, almost no vignetting and I can use the fullframe sensor to the last pixel except where the camera mirror is. I have rewritten parts of my project so you can start reading from the beginning or here: http://astrofriend.eu/astronomy/projects/project-three-inch-flattener/page05-project-three-inch-flattener.html Only one drawback, the f/7 telescope setup is slower than f/5.3, in practice not that big difference because now I can use bigger part of the sensor when I don't have to crop away the vignetted parts. /Lars
  8. Excel Astronomy calculations

    Hi, Earlier I have shared my Astronomy Excel equations, now I'm in the learning process how to do the calculation direct on the web page. I have started with the first one, which is not in the excel sheet. In this calculation you find how many pixels a star moves when you have the camera on a tripod (without a motor). It not just calculate for the eclipta, it do it for the DEC angle where the center of sensor is pointing, and the bottom an top of the sensor along the DEC axis. The last two could be important when having wide angle lenses. Take a look: http://astrofriend.eu/astronomy/astronomy-calculations/max-exposure/max-exposure.html This is very new for me, what I have understand you must have a HMTL5 compatible web browser. I will develop it further. Merry Christmas and a Happy New Year to all of you! /Lars
  9. Replacing a 2.5" flattener with a 3" flattener

    Hi, After one year delay I started up my telescope and mount to do some testing with the new 3" field flatter system. I have not done very deep test yet but already now see it looks promissing with very low vignetting. But the distance between the field flatter and sensor must be wrong. You can read more here with photos: http://astrofriend.eu/astronomy/projects/project-three-inch-flattener/project-three-inch-flattener.html#part06 I have ordered a low profile adapter and then save 10 mm, I hope this will be enough to do some test. /Lars
  10. Hi, What can you do during a rainy and boring day? Yes, write something about about old project ideas that newer have been realized. For many years I have been wondering how to construct a beam splitter system to make more efficient use of exposure time when doing color or narrow band imaging. I have today written down my ideas here: http://astrofriend.eu/astronomy/projects/project-high-efficiency-narrow-band-imaging/project-high-efficiency-narrow-band-imaging.html There are a lot of interesting links there too to read. /Lars
  11. Time efficiency simulations of three cameras

    Hi Jesper, All telescopes are thought to have focallength that give 1" / pix, see row 18. Then more pixels cover more fov and then less number of images to cover a 100 millions pixels fov, see row 24. It's the same as if had been calculated to cover a degree x degree fov, but it was in this case better to use pixels as a calculation base. I hope you find some use of it. You live in Frence but speak Swedish? /Lars
  12. DIY Big Binoculars mount

    Hi DeepSky Man, Yes I have seen that one, looks to be very well made. I just have one arm and only using it when standing up, it's cold in Sweden at winter. It's a bit limited to 50 degree latitude, but even that will take me some years to investigate :-) Thanks for the link! /Lars
  13. Time efficiency simulations of three cameras

    Hi, Because I don't have all data and it's a bit simpliefied in the calculations you shoud not use this to which camera to buy. If you have more correct data for a particular camera you can overwrite the data in green fields. All cameras are very good. It's more about how to use the camera. If you want to take many short expousures to frezze the seeing you should not have a mechanical shutter. If you have a hot outdoor temperature a uncooled dslr is not the first choise. What's very interesting to see is, if I shorten the exposure, how many more subimages do I need to reach the same S/N for that camera. Or how short exposure must it be to not oversaturate bright objects. How does the iso/gain setting influence the time it takes to reach a given S/N. How does the temperature setting change the S/N, Etc Just test with different input data (red field) and see what you get. That's the main purpose of this excel. And take a look at my homepage if I have done any update of the file since last time. Lars
  14. EQ mount with no meridian flip

    There are more then just the cameras get upside down. If I want to ad a second telescope in future I can't have it on the other side of DEC axis. It will collide with the pier or mount. The Lacerta arm works, but that big one I can't fit in my observatory. Must have it compact! The Avalon is a master piece, but 4000 Euro? I added more drawings about my idea to solve this: http://astrofriend.eu/astronomy/projects/project-eq-mount-with-no-meridian-flip/project-eq-mount-with-no-meridian-flip.html /Lars
  15. EQ mount with no meridian flip

    Hi, Yes they are great mounts, but this have to be a low cost solution. After googled around and with your links I see that I must reuse my EQ6 mount and rebuilt it. But no hurry to solve it, I can use it as it is until I found a solution I like and can manage to do. I'm lucky to live at high latitude and don't have to tilt the arm very much. Thanks for the help! /Lars