therealslimfigge
Active member
I'm reading the HVX ISO at about 320. If the gain is cranked up to the other two options, what are the new ISO readings?
HVX Gain ISO
- Thread starter therealslimfigge
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Barry_Green
Moderator
Each 6dB = doubling of brightness, so at 6dB it's sort of 640, at 12dB it's sort of 1280, and at 18dB it's sort of 2560.
I say "sort of" because gain isn't going to actually increase sensitivity, it only artificially increases brightness. You won't see more shadow detail at 18dB than you will at 0dB.
I say "sort of" because gain isn't going to actually increase sensitivity, it only artificially increases brightness. You won't see more shadow detail at 18dB than you will at 0dB.
An increase in the brightness of the output image in response to the same input source is indeed an increase in sensitivity. So, up to a point, it's OK to say the ISO rating is higher. What that point is depends on the signal-to-noise ratio we wish to work with: as we crank up the gain, the SNR drops (we get a heap more noise for a modest gain in signal - you don't see more shadow detail mainly because you see much more noise), so the ISO rating is not a straight doubling even if the brightness of the image doubles. To that extent, Barry is quite right to qualify his figures with a 'sort of'.
Tom
Tom