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G9 will not hold MF focus in Av mode with screen off, help?

Started Jan 14, 2021 | Questions
Boris Starosta
Boris Starosta Forum Member • Posts: 53
G9 will not hold MF focus in Av mode with screen off, help?

Hi there,

I'm using a PowerShot G9 for time-lapse imaging. To save power, I turn the screen off when the cameras are capturing a sequence (I get run times of about 2 hours, shooting a frame every two seconds). When shooting in manual (M) mode, I can set a manual focus, and it stays put.

But when shooting in Av mode with the screen off, the camera seems to take one exposure at the MF setting, then reverts to AF, which slows down the rate at which I can obtain exposures, especially when it gets very dark.

How can the G9 be set to NOT revert to AF... to keep the MF focus setting through several/many subsequent exposures, with the screen turned off and shooting in Av mode?

I studied the manual to no avail - following the somewhat confusing directions did not help solve the problem.

Thanks for any tips!

Boris

 Boris Starosta's gear list:Boris Starosta's gear list
Canon PowerShot G9 Fujifilm FinePix Real 3D W3 Panasonic Lumix DMC-3D1 Sigma DP1 Merrill Sigma DP2 Merrill +5 more
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Sue Anne Rush
Sue Anne Rush Senior Member • Posts: 6,285
Re: G9 will not hold MF focus in Av mode with screen off, help?

Will this help?

https://www.usa.canon.com/internet/portal/us/home/support/details/cameras/support-point-and-shoot/powershot-g-series/powershot-g9/powershot-g9

Boris Starosta wrote:

Hi there,

I'm using a PowerShot G9 for time-lapse imaging. To save power, I turn the screen off when the cameras are capturing a sequence (I get run times of about 2 hours, shooting a frame every two seconds). When shooting in manual (M) mode, I can set a manual focus, and it stays put.

But when shooting in Av mode with the screen off, the camera seems to take one exposure at the MF setting, then reverts to AF, which slows down the rate at which I can obtain exposures, especially when it gets very dark.

How can the G9 be set to NOT revert to AF... to keep the MF focus setting through several/many subsequent exposures, with the screen turned off and shooting in Av mode?

I studied the manual to no avail - following the somewhat confusing directions did not help solve the problem.

Thanks for any tips!

Boris

 Sue Anne Rush's gear list:Sue Anne Rush's gear list
Canon PowerShot G9 Panasonic Lumix DC-FZ1000 II Canon PowerShot Zoom Canon EOS 7D Canon EOS Rebel T7 +4 more
arrow501 Senior Member • Posts: 1,030
Re: G9 will not hold MF focus in Av mode with screen off, help?

Hi Boris, I think you need to switch the Safety MF setting to Off.

 arrow501's gear list:arrow501's gear list
Canon PowerShot SX240 HS Sony RX100 Panasonic Lumix DMC-FZ300
reyalp Regular Member • Posts: 201
Re: G9 will not hold MF focus in Av mode with screen off, help?
1

Boris Starosta wrote:

Hi there,

I'm using a PowerShot G9 for time-lapse imaging. To save power, I turn the screen off when the cameras are capturing a sequence (I get run times of about 2 hours, shooting a frame every two seconds). When shooting in manual (M) mode, I can set a manual focus, and it stays put.

How are your recording timelapse? From the manual, I think the native timelapse feature only works in movie mode, so CHDK?

If it's CHDK, what script, and is the script turning of the screen and setting MF mode, or are setting those manually before running the script?

And just to be sure, you're talking about the 2007 era G9, not a G9 X model, right?

I have an A540 which is similar era, and it does not keep manual focus when the display is turned off, no matter what the shooting mode. I think this is an intentional "feature" in the Canon firmware, to keep people from accidentally leaving MF on while shooting with the viewfinder.

Boris Starosta
OP Boris Starosta Forum Member • Posts: 53
Re: G9 will not hold MF focus in Av mode with screen off, help?

Arrow501: that is a great suggestion, I had not thought of those "features."

Interesting: those features are not adjustable in the menu, if the screen is off (for shooting).  But if I turn the screen on for shooting, then the menu shows those features as adjustable.  Indeed they were turned on!  I turned them off.   That's the good news.

The bad news is, that when I set my manual focus, then turn the screen off for shooting, the camera reverts right back to auto-focus, plain and simple.  Actually, I now discovered that even in manual exposure mode (M), it does the same thing.  Canon must believe that manual focus cannot be useful unless the screen is on (in a way that's true - you can't very well adjust focus with the screen off.  But I can think of many photo situations where you would shoot fixed focus, with the screen off, to obtain better responsiveness from the camera).

Apparently, I must now suspect that all of my time-lapse series have been shot with auto-focus on.  I've just never noticed before, because if I'm shooting midday, with plenty of light, AF runs very quickly and consistently.  Now that I'm shooting dusk scenes, with the light dimming down to darkness, the AF is taking variable amounts of time (ever longer as dusk progresses).  Worse: as it gets darker, AF does not always settle on the same focus/distance setting, resulting in random, minute shifts in the image size of the exposures in the series.

I appreciate your great input, but alas my problem is not solved.  Perhaps it is not solvable.

 Boris Starosta's gear list:Boris Starosta's gear list
Canon PowerShot G9 Fujifilm FinePix Real 3D W3 Panasonic Lumix DMC-3D1 Sigma DP1 Merrill Sigma DP2 Merrill +5 more
arrow501 Senior Member • Posts: 1,030
Re: G9 will not hold MF focus in Av mode with screen off, help?

Sorry to hear that. I don't think there is anything else you could try unless there is something in CHDK that would allow manual focus with the screen off. https://chdk.fandom.com/wiki/CHDK

It might be worth leaving the screen on but dimming it to it's lowest setting to see how long the battery lasts. It may not be too bad compared to what you've been getting if AF has been on all the time without you knowing. Disabling sounds and image stabilisation(if you haven't already) would also help.

 arrow501's gear list:arrow501's gear list
Canon PowerShot SX240 HS Sony RX100 Panasonic Lumix DMC-FZ300
reyalp Regular Member • Posts: 201
Re: G9 will not hold MF focus in Av mode with screen off, help?
1

Turning the screen off with CHDK  set_lcd_display(0) will almost certainly work, but likely won't save as much power. The native "display off" mode turns of the sensor between shots, while the CHDK function just turns off the LCD panel and backlight, leaving all the sensor and other display hardware running. Running the live view continuously accounts for a significant fraction of the power draw.

You can also make these cameras turn the display off by making them think a TV out adapter is connected (a toothpick in the video out port for cameras of this era), but again this has relatively little power saving benefit.

It's possible that using CHDK set_mf(1) after the display has been turned off will work. From a quick test, it appeared to work for me on A540.

It has been observed that MF mode actually uses more power on some of these cameras, so an alternative would be to use CHDK subject distance override (script set_focus before shooting) to set the focus instead. However, in this case the camera will still do an AF scan every shot, which could slow down shooting, especially in low light.

Boris Starosta
OP Boris Starosta Forum Member • Posts: 53
Re: G9 will not hold MF focus in Av mode with screen off, help?

Hi Reyalp, thanks for the extensive reply.

I am shooting stereo time-lapse with two old (original) powershot G9 cameras, indeed modified with CHDK, and running under something called Stereo Data Maker.  The mods to the the data structure of SD cards (i.e. separate boot partition, etc.) was done by someone else, so I'm leery of doing any "code" myself.

I'm nearing the end of my project, which has been underway for some four years now (3d time-lapse of a major construction project), so I think I'll just put up with the problems I'm now having shooting these dusk scenes, rather than risk bricking the cameras at this late stage!

These cameras have been amazing: (knock on wood) over the past four years of image acquisition, I've actuated the shutters at least a half million times.  And they were already used cameras when I got them in 2016!

Anyway, thanks for your extensive message, though it brought bad news!

Boris

 Boris Starosta's gear list:Boris Starosta's gear list
Canon PowerShot G9 Fujifilm FinePix Real 3D W3 Panasonic Lumix DMC-3D1 Sigma DP1 Merrill Sigma DP2 Merrill +5 more
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