Camera Setting to use for Astrophotography
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On the camera we need to be able to control 4 things at the same time to be able to gather enough focused light, they are: Shutter speed, aperture, ISO and to be able to manual focus or atleast be able to set the focus to a distant point. Some models of camera will have a bulb setting directly on the photo mode dial in which case use this other wise choose M (manual exposure) which will let you change both the shutter speed and aperture, make the shutter speed longer until you get to bulb (bulb means that if you were to hold down the shutter buttom the shutter will stay open until you release the shutter button) and the aperture wide open (quite obviously the larger the apperture the more light that will come into the camera) or use the chart below. If your camera doesn't have a bulb setting then you will be restricted to the maxium setting on the camera usually this is 30 seconds. ISO (International Standards Organization) is basically a setting on the camera to tell the sensor how much to react to light, the higher the ISO the more light you will get but at an expense of getting a lot more camera noise - so if the sky conditions are good try for a lower ISO. Heres an idea of how ISO and aperture effect the shutter speed required to gather a similar amount of light.
Exposure times required in minutes when comparing aperture and ISO
|Exposure time (Minutes)
These exposure times will give you a good amount of light for processing on the computer afterwards and are good for one shot photos, or for exposures that are going to be averaged together (not stacked). If there is a moon (over 1/4) or you live in an area that doesn't have a dark sky then your exposure times will have to be less, or you will have to get a filter to block the type of light which is present.