jimhare
lvl.4
Flight distance : 239035 ft
Australia
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Hi Helen,
Technically speaking, ISO is the sensitivity to light, loosely can be described as a gain control (it originally referred to film stock), and the shutter speed is literally how many times the shutter opens and closes each second, which can reduce or increase the amount of actual light allowed through.
So the faster the shutter, the less light gets through and the darker the image. The opposite is true with slower shutter speeds.
With ISO the lower numbers make darker images and larger numbers make brighter images.
Traditionally in photography you would also have a third way to control the exposure, which is opening and closing the lens' aperture (iris) to let more or less light which also allows you to control depth of field.
So in a perfect world you would use a combination of these three things to create your exposure.
Since the Inspire's lens has a fixed aperture of f/2.8 that you can't change, we have to make do with only using shutter and ISO.
Soooooo...
The settings you choose depend on the look you want to achieve.
If you are going for a cinematic look, set the shutter speed to double your frame rate (24FPS = 48 shutter, 30FPS = 60 shutter) and so on.
Do this first then adjust the ISO up or down until you have the correct exposure (use the over exposure warning and histogram to determine this.)
Sounds simple but there's a problem, in the sun you will have your shutter set correctly and the ISO at its lowest setting of 100, but the image is still too bright. This is when you put the ND filter on (which is the darker of the two lens filters provided.)
This will work the same way sunglasses do for your eyes, it reduces the amount light getting to the sensor, which allows you to use a lower shutter speed.
But there's another problem, even with the ND on the image may still be too bright. If this is the case your only choice is to increase the shutter speed until it's under control. If you only need to put it up to 150 or 200 you will probably be fine, but if you have to put it up to 500 to control the light you may get weird effects, including the dreaded rolling shutter jello.
Hopefully some stronger NDs will hit the market. Some users have experimented with cutting their own ND from lighting gels.
Anyway, that's a crash course in exposure. These are by no means definitive rules but as a guideline should be good.
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