EOS RP Aperture changed in Av mode, with a timer.

[peterr]

I took a series of photo for a time lapse video. I was using "Av Mode", "Timer", then F11, ISO 200, auto shutter. EOS RP, RF 24-105 F4, IS OFF, MF. It was during sun set and blue hour. Later I checked the photo, and the aperture changed automatically to F22 in just 3 shots.

F11, F16, F22, F22, F22......

Why was that happened? Was my fault for wrong settings? How can I solve the problem?

[Tiffany]

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Thank you

[NatalyaP]

Greetings peterr,

For clarification, are you shooting still photos in the Interval Shooting mode on the EOS RP or are you shooting a timelapse video in the video shooting mode? You did state that three of the images were at f/22 but you also list one image at f/16. Did you make this adjustment yourself to the lens to f/16?

You may test the camera and try shooting with it again with similar settings to see if the issue repeats itself.

[peterr]

Dear Natalya P,

Glad to receive your reply. I was shooting still photos in the Interval Shooting mode, and I was using a tripod. I did not adjust the aperture during the shooting. I felt weird when I realized the shutter was abnormally longer than what I expected. So that to find the reason, I stopped and checked the series of photo. I found the aperture changed in the interval series. Aperture of the first three photos was F11, F16, F22. The aperture of the remaining photos was F22.

I will try to shoot another series of photo these days, and let's see if this problem still exist.

Warmest regards, Peter.

[Waddizzle · Accepted solution]

There are far too many unknowns to explain what happened beginning with other camera settings like active AF point(s), AF Mode, Metering Mode, lens hood(?), etc.  These questions are rhetorical.

If the camera is setting one or more legs of the exposure triangle, then you can always expect the unexpected to raise its head from time to time.  For example, as available light changed the camera may override your settings because “Safety Shift” is enabled.

I would suggest that when you attempt another time lapse video that you set the camera to M mode.  This gives you complete control over Tv and Av.  You can dial in an ISO setting, or you can set it to ISO AUTO.  If you do select AUTO, then I suggest that you go into the menus and select a maximum ISO setting that the camera can select when in ISO AUTO mode.

[peterr]

Thank you, Waddizzle. I see your point, and your answer inspired me a lot. It is brilliant and witty to consider M mode as an equivalent Av or Tv or even Fv mode under specific settings.