New answers tagged stars
Even though the distance of various stars from your camera on Earth can vary by astronomical distances, they are all far enough away that the light from them enters your lens as collimated rays. This means you don't need much depth of field because the lens must be focused to precisely infinity for any and all of them to be in sharpest focus. The reason the ...
You don't need to use the widest aperture. In fact, in many cases, using the widest aperture for astrophotography can result in very poor quality stars. If you are doing wide field untracked imaging (i.e. milky way imaging), then you can usually get away with using maximum aperture, and the larger aperture allows you to use shorter exposures, which reduces ...
Widest apertures allows you to capture more light, and using a wide angle lens, the depth of field is considerably bigger. And if you focus at infinity, basically nothing will be out of focus. ;)
I am using a Nikon D7000 and have found that using the "Daylight" preset produces a far too orange color cast. I have switched to using a custom temp of about 3300 that works rather well.
Star trails occur because stars "move" across the sky as the Earth rotates, and so when a camera keeps its shutter open for an extended period of time it will absorb this moving light as light trails. For longer trails, other techniques can be used to combine multiple photos of stars. For example, Adobe Photoshop has an "Apply Image" feature that can be used ...
Field distortion would be an overall blur nearer the edges rather than anything you could conceivably call a trail; the stars would simply be fuzzier round blobs. You are using the equivalent of a 600mm lens (200mm times 1.5 (crop factor) times 2 (doubler)). That means that an arc-second is about half a pixel on your 24MP sensor. (The vertical field of view ...
I just went through this same question and found some answers by testing several wide angle lenses (including the Rokinon). Result was that the new Tamron SP 15-30mm was the best all around choice, albeit at a higher cost. The Rokinon 14mm also faired well. See the details here: http://www.ronbrunsvold.com/tools/wide-angle-lenses-for-night.html
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