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"I much prefer star trails, or those pictures of galaxies, how do they do that?", asked Neil (mentalblock) in another 'thread in this, and I said I would answer it in s separate 'thread', so as to intrude in the other 'thread'. So here goes:
The easiest way to capture star trails, is to set the camera on a tripod, and point it at Polaris, the Pole Star. Because Polaris is very close to the Celestial Pole, all of the other stars appear to rotate around it. Of course it the Earth that's moving, not the stars.
If the light pollution is not too bad, you can leave the shutter open, and the stars will begin to trail in a circle around the Pole Star.
Galaxies, and other deep-sky object, is a very different matter, as the camera needs to track the object at Siderial Rate. That is the rate at which the stars appear to move across the sky, or more correctly, the Earth spins on its axis. If this is not done with precision, the stars will elongate, and the object (Galaxy etc) will smear and blur.
This requires that the camera be mounted on Equatorial motor driven mount. For something as simple as DSLR, an Astrotrac, or DiY 'Barn Door Tracker' will suffice. For a telescope mounted camera, the mount get more complex and expensive.
To be really effective, the DSLR needs to be modified, by having its Infra Red blocking filter removed. However, it then no longer really suitable to terrestrial photography.
I don't use my DSLR for my astro-imaging, but use specialised cameras, where the CCD is cooled to minus 20 to 30 degrees C below ambient, thus allowing long exposures with minimal thermal noise.
Astro-imaging is a very different 'ball game' to normal terrestrial photography, both in terms of image capture, and image processing. It can also be just as expensive as photography, if not more so, depending on how deep you want to go.
As such, its outside the scope of this forum, which is aimed at terrestrial photography.
To whet your appetite, should you want to venture into the 'Dark Side', here's an image of "one of those galaxies". I should add that this particular galaxy (The Andromeda Galaxy) is with the capability of a suitably mounted DSLR.
It comprises 45mins exposure through a Red Filter, 45min for Green, 45min for Blue, and 45min through a neutral filter, making 3 hours of total exposure time.
Dave
The easiest way to capture star trails, is to set the camera on a tripod, and point it at Polaris, the Pole Star. Because Polaris is very close to the Celestial Pole, all of the other stars appear to rotate around it. Of course it the Earth that's moving, not the stars.
If the light pollution is not too bad, you can leave the shutter open, and the stars will begin to trail in a circle around the Pole Star.
Galaxies, and other deep-sky object, is a very different matter, as the camera needs to track the object at Siderial Rate. That is the rate at which the stars appear to move across the sky, or more correctly, the Earth spins on its axis. If this is not done with precision, the stars will elongate, and the object (Galaxy etc) will smear and blur.
This requires that the camera be mounted on Equatorial motor driven mount. For something as simple as DSLR, an Astrotrac, or DiY 'Barn Door Tracker' will suffice. For a telescope mounted camera, the mount get more complex and expensive.
To be really effective, the DSLR needs to be modified, by having its Infra Red blocking filter removed. However, it then no longer really suitable to terrestrial photography.
I don't use my DSLR for my astro-imaging, but use specialised cameras, where the CCD is cooled to minus 20 to 30 degrees C below ambient, thus allowing long exposures with minimal thermal noise.
Astro-imaging is a very different 'ball game' to normal terrestrial photography, both in terms of image capture, and image processing. It can also be just as expensive as photography, if not more so, depending on how deep you want to go.
As such, its outside the scope of this forum, which is aimed at terrestrial photography.
To whet your appetite, should you want to venture into the 'Dark Side', here's an image of "one of those galaxies". I should add that this particular galaxy (The Andromeda Galaxy) is with the capability of a suitably mounted DSLR.
It comprises 45mins exposure through a Red Filter, 45min for Green, 45min for Blue, and 45min through a neutral filter, making 3 hours of total exposure time.
Dave
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i can only dream about such an image. Appears to be bit more interest on tp for astrophotography lately. Off to drool over image again. Please show more . Have a
