baschie
24th of April 2003 (Thu), 16:15
Hi,
I'm a science student at the University of Nijmegen (the Netherlands), and we've got an 8" f/10 refractor telescope in a dome on the roof of our department building. It was made hand made (lens hand grinded) for a French baron a 100 years ago, because he wanted to be famous. He wanted to find a comet and give his name to it. He never succeeded, and in the sixties, his heirs sold the telescope to our university. They kept the object lens and the ocular tube, and rebuilt the rest from scratch. It is equatorially mounted and has a little motor running against the earth’s rotation.
I teach first year astro-physics students to work with this old telescope, this teaches them the equatorial coordinate system, some basic optics, and astrophotography (we use an old sbig ST-6 astro CCD camera).
A friend of mine has a Canon D60, and we've tried to take some photos with this telescope. Remember, this telescope has a lot of chromatic abberation, and I'm taking these photos in the middle of a city (of about 130,000 people). We used an EOS to T-thread converter ring, and I made our mechanics make a ring converting T-thread to our thread (M45x1.0).
If you click on this link (http://baschie.com/picture.php?pageTitle=astro&part=2&pic=0), you get a gallery starting of with a D60 image of our telescope, and then some astronomy pictures made by this D60 through our telescope.
The D60 is not ideal for astrophotography. The pixels are far too small, and therefore noise is high (especially on an 8" f/10 telescope). The chip is not cooled, and therefore dark-frames are needed (taking pictures with the lid on, with the same exposure time as the original photograph, averaging them, and subtracting them from the astro-photographs). I think the bad quality of the pictures is mostly due to the small telescope, the large chromatic abberation and the dark-noise. I don't know about the quantum efficiency, but I bet it's much worse than professional astro-cameras (but also a lot cheaper).
All in all, I did my best to debunk my pictures, now it's your turn.
Bastiaan
again the link, for those of you who couldn't find it in this massive amount of text (http://baschie.com/picture.php?pageTitle=astro&part=2&pic=0)
I'm a science student at the University of Nijmegen (the Netherlands), and we've got an 8" f/10 refractor telescope in a dome on the roof of our department building. It was made hand made (lens hand grinded) for a French baron a 100 years ago, because he wanted to be famous. He wanted to find a comet and give his name to it. He never succeeded, and in the sixties, his heirs sold the telescope to our university. They kept the object lens and the ocular tube, and rebuilt the rest from scratch. It is equatorially mounted and has a little motor running against the earth’s rotation.
I teach first year astro-physics students to work with this old telescope, this teaches them the equatorial coordinate system, some basic optics, and astrophotography (we use an old sbig ST-6 astro CCD camera).
A friend of mine has a Canon D60, and we've tried to take some photos with this telescope. Remember, this telescope has a lot of chromatic abberation, and I'm taking these photos in the middle of a city (of about 130,000 people). We used an EOS to T-thread converter ring, and I made our mechanics make a ring converting T-thread to our thread (M45x1.0).
If you click on this link (http://baschie.com/picture.php?pageTitle=astro&part=2&pic=0), you get a gallery starting of with a D60 image of our telescope, and then some astronomy pictures made by this D60 through our telescope.
The D60 is not ideal for astrophotography. The pixels are far too small, and therefore noise is high (especially on an 8" f/10 telescope). The chip is not cooled, and therefore dark-frames are needed (taking pictures with the lid on, with the same exposure time as the original photograph, averaging them, and subtracting them from the astro-photographs). I think the bad quality of the pictures is mostly due to the small telescope, the large chromatic abberation and the dark-noise. I don't know about the quantum efficiency, but I bet it's much worse than professional astro-cameras (but also a lot cheaper).
All in all, I did my best to debunk my pictures, now it's your turn.
Bastiaan
again the link, for those of you who couldn't find it in this massive amount of text (http://baschie.com/picture.php?pageTitle=astro&part=2&pic=0)