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Old May 10, 2015, 9:29 AM   #1
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Hi,
I was thinking that I could kill two birds with one stone by setting high iso in menu, and then having the option of low iso in the RAW file, but that doesn't seem to be how it works?
..... john
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Old May 10, 2015, 2:44 PM   #2
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In practice, ISO is the amount of amplification the camera applies to the signals each photoreceptor generates from the light it detects. Doubling the ISO doubles the amplification, but the camera accounts for that doubling by halving the exposure time and/or aperture. Once you've set the exposure settings (or accepted the settings the camera has selected for you) you're stuck with them. Changing the ISO in post processing would be like changing the shutter speed.
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Old May 10, 2015, 4:52 PM   #3
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Shinnen- Your camera uses three parameters for a correct exposure- size of aperture (increasing or decreasing amount of light coming in), shutter speed (less or more time to let light in) and the camera's sensitivity to light itself (iso high or low setting).
All RAW shooting does is enable more finite adjustment during post processing (as it retains more of the original data captured) as opposed to the in camera's processed file (jpeg)...
Adjusting the sensitivity AFTER the event is not possible... though you could drop the exposure setting down during processing- which would in effect be like reducing the original iso setting- though I don't envisage any scenario whereby one would WANT to do that- as you'd just end up with an under-exposed image..!!
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Old May 10, 2015, 9:55 PM   #4
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Hi TCav/Simon,
Right, well, I guess I was hoping that 'raw' meant 'completely unprocessed' (whatever that means), whereby the camera magically chooses some baseline iso, aperture, etc. and then applies the menu settings to that file. I really don't know how these things work.
...... john
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Old May 11, 2015, 11:11 AM   #5
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You can change the sensitivity after the fact when processing a Raw image, but you have to do it within the fixed parameters of shutter speed and aperture, which can't be altered once the shot is taken. Depth of field and the overall amount of light reaching the sensor, are the two things which the lens and camera fix.
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Old May 16, 2015, 9:16 PM   #6
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Thanks VTphotog.
i was afraid of that.
....... john
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