Tom Morrow
August 1st, 2011, 09:50 PM
There's been some speculation in this thread
http://www.dvinfo.net/forum/all-things-audio/498727-agc-disable-magic-lantern-vs-juicedlink.html
that the Canon DSLR native firmware only allows one to adjust the audio digital gain up or down, and that the analog gain on Canon DSLRs is fixed at its chip's max value of +31dB. This means that Magic Lantern would give the lowest noise signal because it exposes the ability to turn down the chip's analog gain to a level that isn't so noisy (the ML manual says around +20db is where the chip gets noisy, so Jon from this forum recommends +10 or +17db analog gains only).
If anyone has test results or references that prove or disprove the analog gain being fixed with the Canon firmware, please let me know and/or post. If this is true, then a followup question is why does anyone bother adding digital gain (with Canon firmware gain setting or ML digital gain setting) as long as they have the ability to adjust gain in post production? Both digital gain and post/NLE gain are the same in their effect on noise except that NLE gain clipping is reversible by reverting to the original recording file.
http://www.dvinfo.net/forum/all-things-audio/498727-agc-disable-magic-lantern-vs-juicedlink.html
that the Canon DSLR native firmware only allows one to adjust the audio digital gain up or down, and that the analog gain on Canon DSLRs is fixed at its chip's max value of +31dB. This means that Magic Lantern would give the lowest noise signal because it exposes the ability to turn down the chip's analog gain to a level that isn't so noisy (the ML manual says around +20db is where the chip gets noisy, so Jon from this forum recommends +10 or +17db analog gains only).
If anyone has test results or references that prove or disprove the analog gain being fixed with the Canon firmware, please let me know and/or post. If this is true, then a followup question is why does anyone bother adding digital gain (with Canon firmware gain setting or ML digital gain setting) as long as they have the ability to adjust gain in post production? Both digital gain and post/NLE gain are the same in their effect on noise except that NLE gain clipping is reversible by reverting to the original recording file.