I'm shooting with a Sony A7C and a 35mm f/2.11 ZA Lens. Suppose it's the middle of a Summer day at high altitude. I'm using the Intelligent Auto setting, the camera identifies the scene as landscape, and chooses an aperture of 11 and a shutter speed of 1/250.
I believe this means the camera has decided my best focus / sharpest image / depth-of-field will be at aperture 11: it could have also chosen 13 with a shutter speed of 1/200 or so, still plenty fast to avoid camera shake, but decided 13 would have too much diffraction.
Suppose I'm at this same location and there is less light. My camera might choose aperture 8 and shutter speed 1/60 because it needs a larger opening for a fast-enough shutter speed. I believe I can put the camera on a tripod, set the aperture to 11, and shoot at whatever shutter speed because the tripod will take care of shake.
Ok, here's the question. Suppose I arrive at a new location with my tripod. My camera chooses aperture 8 and shutter speed 1/60. I have not been to this spot before and so I do not know what my camera would choose in a higher-light situation. I'd like to choose the aperture which gives the sharpest image, regardless of shutter speed because of the tripod. How do I determine what that aperture would be?
I realize the phrase "less light" is imprecise: light has direction and quality, not just intensity, but can that be ignored for now?