Ixus 185 manual focus possible? - General Discussion and Assistance - CHDK Forum
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Ixus 185 manual focus possible?

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Offline davidvankemenade

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Ixus 185 manual focus possible?
« on: 01 / January / 2021, 11:11:29 »
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Does anyone know wheter CHDK supports manual focus on the Ixus 185? The menu (attachment) seems to indicate it does, but I don't know where the DISP button is. Also, ptpCamGui shows the manual focus slider disabled. Thanks in advance for any help with this.
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Offline reyalp

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Re: Ixus 185 manual focus possible?
« Reply #1 on: 01 / January / 2021, 15:44:01 »
Quote from: davidvankemenade on 01 / January / 2021, 11:11:29
Does anyone know wheter CHDK supports manual focus on the Ixus 185?
According to how the port is configured, it should support subject distance override in all focus modes (AF, AF lock and MF). However, the discussion in the porting thread is a bit ambiguous.

Note it probably won't work if the camera is in "AUTO" shooting modem, or if continuous AF is enabled in the Canon menu.

Since you have PTP set up, you can using chdkptp. Using the GUI, with the camera connected and switch to rec mode:
=set_aflock(1)
=set_focus(100)
=set_focus(10000)
you should see the focus immediately after each set_focus. Use set_aflock(0) to leave aflock, then set_mf(1) for MF and repeat. set_mf(0) to turn off MF.

In auto focus mode (with neither set_aflock nor set_mf active) the focus only updates immediately before shooting, so you can test in chdkptp with the shoot command like:
shoot -sd=0.01
shoot -sd=10
and compare the photos

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The menu (attachment) seems to indicate it does, but I don't know where the DISP button is.
Indeed, it doesn't have one, which means that shortcut will not be available. This is a general problem in CHDK where assumptions are made about which keys cameras have. However, you should still be able to enable "Override subj dist." in the "enhanced photo operations" menu. You can also toggle all enabled overrides overrides using the half press + down shortcut.
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Offline davidvankemenade

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Re: Ixus 185 manual focus possible?
« Reply #2 on: 02 / January / 2021, 10:47:06 »
Many thanks for your help @reyalp! I've got the manual focus working in this way.

Now I'm hitting the next problem. My subject, a photo album, is lit by a LED light. I assume there is a 50 Hz flicker in the illumination which seems to upset automatic exposure settings in the Ixus 185. The preview image is constantly oscillating between black and much overexposed. Which settings should I fix to stop that from happening?
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Offline reyalp

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Re: Ixus 185 manual focus possible?
« Reply #3 on: 02 / January / 2021, 15:43:09 »
Quote from: davidvankemenade on 02 / January / 2021, 10:47:06
Many thanks for your help @reyalp! I've got the manual focus working in this way.
Can you confirm which focus modes the override works in?
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Now I'm hitting the next problem. My subject, a photo album, is lit by a LED light. I assume there is a 50 Hz flicker in the illumination which seems to upset automatic exposure settings in the Ixus 185.
If this is really the problem, my first suggestion would be to use different lighting. I've used a lot of consumer LED lights without any issue. I'm not aware of any camera settings to compensate for this. You don't need super bright lighting to photograph a fixed subject like this.

If your light has adjustable brightness, that would likely be done with PWM, and the brightest setting should have least flicker.

You could force the camera to integrate more cycles in the actual shot by putting in the ND filter (ND filter override or set_nd_filter in script), but this only affects shooting, you'd have to figure out the correct exposure yourself.
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Offline davidvankemenade

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Re: Ixus 185 manual focus possible?
« Reply #4 on: 05 / January / 2021, 14:30:52 »
Thanks again @reyalp!

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Can you confirm which focus modes the override works in?
It worked in P Mode, immediately after
=set_aflock(1)
=set_focus(100)

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If this is really the problem, my first suggestion would be to use different lighting.
I'm getting a different light source to see if that solves the flicker.
I'll report back once I've got it and tried it with the Ixus.
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