SX230 HS not able to override exposure settings

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SX230 HS not able to override exposure settings
« on: 21 / September / 2015, 20:21:58 »
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I have SX230HS with firmware 1.01C and CHDK version 1.3.0-4245 loaded. CHDK works, I am able to change image format to DNG, but not able to override aperture and shutter speed. Here is what I have:
Disable overrides - No
Override Tv short set to 0.00001, long set to 0:00:59 and checked
Override Av set to 16 and checked
Disable override on startup is unchecked

I am trying to set shutter speed outside of factory range in Tv, Av and M modes, but my ranges stay 1/3200 - 15 sec; and 3.1-8. What am I doing wrong?

Thank you

Re: SX230 HS not able to override exposure settings
« Reply #1 on: 21 / September / 2015, 20:42:58 »
I am trying to set shutter speed outside of factory range in Tv, Av and M modes, but my ranges stay 1/3200 - 15 sec; and 3.1-8. What am I doing wrong?
Does the shutter speed override to your settings when you shoot in P or AUTO modes?  Does it use your settings if you are inside the factory range?   How do you know it's not using your settings - the values on the Canon display might not tell you what it is actually using.
Ported :   A1200    SD940   G10    Powershot N    G16

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Re: SX230 HS not able to override exposure settings
« Reply #2 on: 21 / September / 2015, 22:09:52 »
I thought that CHDK does not overrides the actual exposure value, but expend the range of available shutter speed, or aperture, That is why I didn't expect to see the change in A or P mode, but I do see it affecting the measured shutter speed in P mode, and I see underexposed images. Which is kind of weird, because it is no longer A or P mode...

You have a good point - should I expect expended range to be shown by Canon display, or CHDK has some other means of showing the actual exposure values?

Thank you for your help.

Re: SX230 HS not able to override exposure settings
« Reply #3 on: 21 / September / 2015, 22:32:35 »
I thought that CHDK does not overrides the actual exposure value, but expend the range of available shutter speed, or aperture,
Well, it actually does both. 

It changes the exposure values based on what you set in the CHDK menu (of via a CHDK script).  And it also extends the range somewhat.   

By somewhat,  that means much longer maximum exposure times and somewhat faster minimum exposure times.   It can't really do anything about extending the aperture settings (f-stop) although getting one additional f-stop smaller has been reported (with a resulting poor image unfortunately).  Similarly, you can't slow the ISO value down much but might be able to extend it some.

Note that if you only change one exposure setting ( Tv, Av, Sv or ND filter) then the Canon firmware will use whatever value it was originally going to use for the other values.  It will not compensate for your change and you will almost always get underexposd or overexposed images.

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You have a good point - should I expect expended range to be shown by Canon display, or CHDK has some other means of showing the actual exposure values?
The Canon values on the display should show what Canon wants to use.  You can enable the CHDK On Screen Display (OSD) to see what CHDK will use instead.   Also,  the EXIF values stored with the image should show what was actually used (i.e. the CHDK overrides) but IIRC this does not always work - especially at extended ranges.

Ported :   A1200    SD940   G10    Powershot N    G16


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Re: SX230 HS not able to override exposure settings
« Reply #4 on: 22 / September / 2015, 19:19:53 »
Thank you for clarification! Main feature that I was looking for - shooting in raw works, that is all I need.

 

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