![]() You can use lower ISOs and longer exposures if you want to capture an image of "star trails" (use a remote wired release to take 30 second exposures and just keep taking them. These will likely be noisy images at ISO 1600. This is going to be a challenge because the max ISO on your camera is ISO 1600 and you'll probably need 1600 (it would be better if you could use ISO 3200). You will still likely need to crank the ISO on your camera. well away from urban lighting (light pollution) and also select a night when the moon is not in the night sky (e.g. To take photos of the stars, you probably want to find the darkest skies possible. if your camera is on a SOLID tripod and not moving (not tracking the stars) then you can take an exposure which is 22 seconds long and you should not be able to notice the stars beginning to elongate (growing "tails") due to the movement of the Earth. if you are trying to capture as much sky as possible then you're probably using the 17mm end of the focal length. you take the base value (in your case, it's 375 due to the sensor size of your camera) and DIVIDE that by the focal length of your lens (in millimeters). This means we have to divide 600 by that crop factor (1.6) and this gets us to 375 as our base value. it's an "APS-C" size sensor and it's smaller by a factor of 1.6. But a Rebel XTi has a sensor which is a bit smaller. ![]() A "full frame" digital camera (like a 1D X, 5D series, or 6D) have a digital sensor which is the same size as a single frame of 35mm film. ![]() This rule was used for 35mm film cameras - but the size of the image frame is important to the rule. This assumes the camera is on a stationary tripod and not on a special "tracking" mount. Stars positioned roughly above Earth's equator move at a rate of 15 arc-seconds (angular movement) per 1 second of real time. Since the Earth is spinning on it's axis, the stars appear to move across the sky. If the camera is connected to a telescpe then you can't control the focal ratio of the telescope (it is whatever it is) - in which case you do a bit of math to work out the shutter speed.ΔΆ) The stars and the "Rule of 600" (which you should think of as the "rule of 375" (or just round it to "rule of 400") ISO 100, f/8, and 1/200th would also be a correct exposure.) With a camera, I'd keep it simple and just use f/11. Since f/8 allows exactly twice as much light to flow through the lens as comapred to f/11, then you might set the shuter speed to expose for only half as long (e.g. If you use a different f-stop (suppose you use f/8 - which allows exactly twice as much light flow through the lens) then you trade a a stop of aperture for a stop of shutter speed (or ISO). If you use ISO 400, set the shutter speed to 1/400th. In other words, if you use ISO 100, then set the shutter speed to 1/100th. When taking a photograph of the moon, you can get a correct exposure using the "Loony 11" rule which suggests that if you use f/11, then the correct shutter speed is always the inverse of the ISO setting.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |