Quote:
Originally Posted by Asr
Ahh ISO, that's another thing I've been clueless about - my night shots never come out good. I need to know how to do night shots better.
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In digital photography, ISO rating defines the sensitivity of the CMOS or CCD image chip (what captures the image when the lenses direct light onto it), and in traditional photography, it's the sensitivity of the film or photographic plate to light.
For example, using an ISO1600 in broad daylight means it takes less time for the CMOS or CCD chip to react to light, and capture the image, as compared to if you were using ISO800.
So the darker the object or location of photography, the higher you set your film speed rating to, right? Wrong. It isn't that simple.
Higher film speed ratings tend to produce an effect called
noise, wherein the image appears grainy. Because of this many photographers prefer to use low ISOs for night photography, and compensate with longer exposure time (shutter speed). I.e instead of using ISO3200 and using a shutter speed of a say, half a second (I can't remember, been a long time since I was into photography
), he may choose to use ISO800 but with an exposure time of 10 seconds. That means the shutter stays open for 10 seconds.
What a long exposure time means, though, is that it isn't good for motion photography, or photography without a stand. The former shouldn't affect you if you're only taking pictures of items around your house (still-life or macro), but the former would if you aren't using a stand, or even a remote (even with a stand, shaky hands can blur a photo, which is why professionals sometimes use a wired remote). This is because when the shutter stays open, the different-intensity (brightness) and frequency (colour) light rays have to be hitting the same spot continuously on the film or image sensor in order for a sharp image to be captured. All those intentional blurred shots of race cars are hence created using longer exposure times (and in a bright location, a lower light sensitivity to compensate).
