I need help with (Tv) (Av) & (Sv) values equivalents to Shutter/Aperture/ISO

Alejandro

« on: 02 / December / 2011, 19:13:20 »

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Let me see if i understand this correct,
cause i'm a little confuse.

I'm testing this script for Manual Video Controls in my SX40,
but i have no idea how Tv/Av/Sv values translate into Shutter/Aperture/ISO

My question is:
If i set my (Tv) to a certain value, let's say 540...
but i change my (Sv) values from shot to shot...
does that mean that my shutter speed is changing every time?

Or this values are totally independent from each other?

Depending on the case...

can anyone help me translate the values equivalents for Shutter, aperture & ISO?

Alejandro.

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ELPH 300HS (IXUS 220)
EOS Rebel T3 (not T3i)
EOS 7D
SD770 IS
SX40 HS
SD1300 IS

waterwingz

12125

Re: I need help with (Tv) (Av) & (Sv) values equivalents to Shutter/Aperture/ISO

« Reply #1 on: 02 / December / 2011, 19:23:52 »

repeat post : http://chdk.setepontos.com/index.php?topic=7185.msg77191#msg77191

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Ported : A1200 SD940 G10 Powershot N G16

Alejandro

Re: I need help with (Tv) (Av) & (Sv) values equivalents to Shutter/Aperture/ISO

« Reply #2 on: 02 / December / 2011, 22:25:02 »

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The moderator got his message.

« Last Edit: 03 / December / 2011, 08:07:58 by Alejandro »

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ELPH 300HS (IXUS 220)
EOS Rebel T3 (not T3i)
EOS 7D
SD770 IS
SX40 HS
SD1300 IS

reyalp

13746

Re: I need help with (Tv) (Av) & (Sv) values equivalents to Shutter/Aperture/ISO

« Reply #3 on: 03 / December / 2011, 00:15:20 »

Anyway, just in case someone else has this question, the cameras generally work in APEX*96 values.

An excellent description of APEX can be found at http://dougkerr.net/Pumpkin/#APEX

Canon firmware use the 96 multiplier to allow calculations to be done with integers. CHDK scripts functions generally also work in these units.

Sv, Tv, Av values are completely independent, adjusting one does not affect the others. However, you can use the APEX equation to calculate how much you should change one to compensate for a change in another.

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Don't forget what the H stands for.