index values for sx240, sd1200, sd890 - Script Writing - CHDK Forum
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index values for sx240, sd1200, sd890

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Offline jmac698

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index values for sx240, sd1200, sd890
« on: 03 / January / 2013, 14:12:56 »
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These are my test results from a simple basic script
Code: [Select]
get_zoom z
print "zoom index", z
get_av a
print "aperture index", a
get_focus f
print "focus index", f
get_iso i
print "iso index", i

Zoom index
camera    index range   zoom range
sd1200    0-6                 1x-3x
sd890      0-11               1x-5x
sx240      0-100             1x-20x

Aperture index
sx240
index     f-stop
9   3.5
10   4.0
11   4.5
12   5.0
13   5.6
14   6.3
15   7.1
16   8.0

sd1200, sd890 have no iris and always return 0

iso index
index  iso-sx240  iso-sd1200 iso-sd890
-1        n/a           n/a              hi-auto
0        auto          auto/3200   auto
1        100            80               80
2        200           100              100
3        400           200              200
4        800           400              400
5       1600          800              800
6       3200          1600           1600

*sd1200 has a scene mode "iso3200" which returns 0.  It's not a true ISO but a pixel binning.

focus index
distance  index-sx240  index-sd1200  index-sd890
5cm         50                 50                   60
10cm       99
20cm       191
50cm       660
2m         2240              1978               2500
inf          -1                   -1                    65535

*sd1200, sd890 have macro, normal, and infinity setting. The inf setting didn't return -1 on sd890
**The values are very approximate. sx240 has a focus display bar graph and I read the bar when
it was in the middle of the number next to it. Not clear how to actually read it.

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Offline jmac698

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Re: index values for sx240, sd1200, sd890
« Reply #1 on: 03 / January / 2013, 15:25:27 »
Using test script http://chdk.setepontos.com/index.php?topic=8316.0

sv96 values (exposure)

iso sv96-sd1200 sv96-sd890 sv96-sx240
80  371               371              n/a
100 411              411              411
200 507              507              507
400 603              603              603
800 699              699              699
1600 795            795              795
3200 n/a             891              891

*sx240 doesn't have iso80, sd1200 doesn't have 3200, sd890 has iso3200 scene mode but it's pixel binning
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Offline waterwingz

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    • Waterwingz
Re: index values for sx240, sd1200, sd890
« Reply #2 on: 03 / January / 2013, 17:54:39 »
You can find these values for any camera in the CHDK source code - file shooting.c  - in the platform subdirectory of that camera.
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline jmac698

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Re: index values for sx240, sd1200, sd890
« Reply #3 on: 03 / January / 2013, 18:10:44 »
Awesome.  Maybe if I get ambitious, I'll try to write some kind of cross-camera scripting guide, or tables of values for various cameras.  I'm only learning this stuff now.
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Offline reyalp

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Re: index values for sx240, sd1200, sd890
« Reply #4 on: 03 / January / 2013, 21:26:12 »
Just FWIW, the camera works in APEX*96 units. These can be used directly via the set_*96 etc function

APEX makes exposure calculations very simple. An excellent is available at http://dougkerr.net/Pumpkin/#APEX

Multiplying regular APEX values by 96 allows the calculations to be done with integers.

ISO is further complicated because the Canon firmware has two different kinds of ISO values "real" and "market", described briefly here http://chdk.wikia.com/wiki/CHDK_User_Manual#Override_ISO_value
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