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Everything posted by MrJulius

  1. The best amateur astronomer ever September 14th: A Tribute to John Dobson on His 95th Birthday
  2. If I interpreted correctly it looks like the 500D is better than the 1000D, contrary to what some people argue that the 1000D has larger pixels than the 500D and therefore more sensitive. But on the other hand it probably is not too much difference in real life. Funny thing I just got the 500D, but quit astro imaging. But I will still try some widefield fixed tripod shots of meteor storms and the starry skies.
  3. Covering the inside of the tube, making it pitch black, so that no light is reflected from the tube walls. It is should give better contrast.
  4. I love your pictures James. I also enjoy photographing airplanes at high altitude. I use a 300mm lens and a 500D, but it is still to little to see any detail. I am going to purchase a SW 10" Dobsonian do you have any tricks of the trade to share with us?
  5. Congratulations, the comparison picture really show the size difference. Can't wait until the day I can buy a 250mm dob myself
  6. SPC900NC/00 Philips Webcam SPC900NC VGA CCD with Pixel Plus - Philips Support
  7. Good question Joe. the way I picture things is that the telescope collects a cone of light, which i view as a circle in 2D if you make a circle with a smaller diameter than the light cone you will get magnification. What you get is a smaller field of view. If you stand outside looking through a frame, then you can imagine that what you see through the frame fill your entire view. Things look larger because you take a little part of the whole picture and fill your entire view with it. The web camera has a smaller ccd chip(the frame) thus it sees only a small part of the complete light cone(whole picture) thereby magnifies it, atlhought magnification is not the right word for it.
  8. I am going on summer holiday to southern Italy in 8 days, am I right in asuming that the comet will be higher up in the sky there? Might try to take some pictures.
  9. Very nice Mel and thanks for the Stellarium info Luke.
  10. Hi John Your setup with the Skywatcher Explorer 250 has a focal length of 1200mm and an apperture of 250mm. F-ratio = focal lenght/apperture = 4.8 The following apply mostly to Deep Sky imaging, it is possible to beat the atmosphere on planetary imaging. You should choose a camera with a pixel size that will provide optimal sampling with your telescope. Disturbances in the atmosphere limits the amount of detail we can resolve here at ground level. The formula is: Pixel Resolution= (pixel size/ focal length)*206.27 Here where I live in Norway the atmosphere won't let me resolve details under about 4 arcsec. By the Nyquist theorem I therefore should have a pixel resolution at half of the 4 arsec = 2 arsec/ pixel An example with the Meade DSI PRO Mono which I have for sale http://stargazerslounge.com/sale/105212-meade-dsi-pro-philips-spc900nc-filters-wheel-heq5-items-sale.html (I know shamless plug ) For the Meade DSI PRO with 9.6µmx7.5µm pixels with the Skywatcher Explorer 250: Width(9.6/1200)*206.27= 1.65016 Arc seconds/pixel Height(7.5/1200)*206.27= 1.28919 Arc seconds/pixel Hope that helps, also somebody from the UK probably knows a suitable pixel resolution, my quess would be that it is about the same as here in Norway. I see there is an excellent sticky thread that explains it proably in better English than me. http://stargazerslounge.com/equipment-help/89946-choosing-ccd-camera.html
  11. Nicely resolved core philj. Can't get enough of globular clusters
  12. Nice M13 Sam, do you have any more info on your homebrew Arduino based guiding system. It works great!
  13. A great start. That is similar to my images, but we will keep getting better
  14. Nice contrast and impressive gear! I didn't realize that the nebula's where so close I have only seen them apart.
  15. Really cool reminds me of a cats eye.
  16. Nice M57 greenkat. It is fun to see the results of people with similar gear as myself. A bit constructive criticism I think you should try to distribute the text more evenly among the left and right corners it will make the picture seem a more balanced, as it is now it is a bit left heavy.
  17. It has a really nice pinkish hue, nice details in the full size image.
  18. Very nice, I really like the black and white images. As for the noise it fits right into the image and gives it an old photography's feel.
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