Aperture Override for IXUS 85/SD770

maor1993

2

« on: 20 / June / 2011, 11:16:09 »

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Hello, I recently got CHDK for my Ixus 85, It's working great but I can't understand there isn't aperture override in the menu, even though I've seen my camera going to lower apertures than f/4.9

I hope you can help me.

Thanks in advance,
Maor.

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fe50

3152
IXUS50 & 860, SX10 Star WARs-Star RAWs

Re: Aperture Override for IXUS 85/SD770

« Reply #1 on: 20 / June / 2011, 11:25:49 »

Hello & welcome, maor1993 !

Quote from: maor1993 on 20 / June / 2011, 11:16:09

I can't understand there isn't aperture override in the menu, even though I've seen my camera going to lower apertures than f/4.9

Almost all IXUS series cameras do not have a real aperture (iris diaphragm), only a ND filter to "emulate" two F states...

With the forum search (look for "ND filter") you'll find more information about this...

* http://en.wikipedia.org/wiki/ND_filter
* http://chdk.setepontos.com/index.php?topic=2841.msg51106;topicseen#msg51106
* http://chdk.setepontos.com/index.php?topic=4141.msg40744;topicseen#msg40744
* http://chdk.wikia.com/wiki/ND_Filter

« Last Edit: 20 / June / 2011, 11:33:17 by fe50 »

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whim

2046
A495/590/620/630 ixus70/115/220/230/300/870 S95

Re: Aperture Override for IXUS 85/SD770

« Reply #2 on: 20 / June / 2011, 11:32:46 »

@maor1993

That's very simple: it's because ixus (with rare exceptions) don't have an iris diaphragm.
Instead, they use a ND (neutral density) filter, which can be manipulated from CHDK:
Extra Photo Operations -> ND Filter state
- Off --> let Canon decide
- In --> force filter in (use)
- Out --> force filter out (don't use)

See also: pdf User Guide, page 9

hth,

wim

edit: darn, out-typed by fe50 again