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09/07/2007 06:56:54 PM · #1 |
Its my ignorance, but I'm always excited to learn.... why have ISO settings on a digital camera? Can't you simply adjust the aperature to get the same results? I understand on a manual camera with manuel film but what is actually going on inside that digital camera differently when adjusting your ISO?
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09/07/2007 07:03:16 PM · #2 |
| You pretty much said it yourself, why you have ISO. You can´t always adjust aperture and the two are not the same, sometimes you don´t want to adjust the aperture and shutterspeed but will end up with a darker picture if you don´t bump up ISO. |
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09/07/2007 07:12:07 PM · #3 |
Consider this: you are shooting with your 70-300 and have it maxed out at f/5.6 at 300mm. You are handheld and don't want to decrease your zoom, so you are stuck at about 1/500 as the lowest shutter speed you can go without camera shake blur. Let's say at ISO 100 you are getting a shutter speed of 1/60.
You then bump the ISO setting up to ISO 400 and wala.. perfect exposure, no camera shake blur.
Now, what you have done is increase the gain on the sensor. This is effectively like turning up the volume on a stereo.
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09/07/2007 07:13:52 PM · #4 |
The ISO in a digital camera mimics high-ISO (high-speed) film by increasing the receptor gain on the sensor. If you're indoors, especially if you can't use flash, you want a higher ISO in order to capture a shot with a usable shutter speed (thinking handheld). Many times aperture is not enough to make that possible (and many times you don't want a wide-open aperture). So the digital camera increases the sensor gain which really just amplifies the light that is hitting the receptors to give you a better exposure, but that amplification causes more noise (just like the more sensitive emulsion on high speed film causes more grain).
ah, Leroy beat me to it (by being more concise)...
Message edited by author 2007-09-07 19:15:43. |
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09/07/2007 07:36:35 PM · #5 |
Wow, thanks guys - this makes more sense. I just couldn't wrap my mind around it.... ;)
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