Why can’t you take a photograph of your image in a plane mirror and focus the camera on both your image and on the mirror frame?
Because your image is behind the mirror, twice as far from the camera as the mirror frame.
When you try to take a photograph of your image in a plane mirror and focus the camera on both your image and the mirror frame, you'll encounter an issue known as the "depth of field." Depth of field refers to the range of distance in a photograph that appears sharp and in focus.
In this scenario, the plane mirror reflects the light back to the camera, which would create multiple depths of field. However, the camera can only focus on one specific distance at a time. When you focus on your image reflected in the mirror, the mirror frame will be at a different distance from the camera, thereby falling outside of the camera's depth of field. As a result, the mirror frame may appear blurry or out of focus in the photograph.
To explain how to address this issue, you would need to adjust the camera settings to increase the depth of field. By increasing the aperture size (using a larger f-number), you allow more light to enter the camera, which results in a wider depth of field. However, this might also require adjusting other settings such as ISO and shutter speed to maintain a balanced exposure. By doing so, you can potentially capture a photograph where both your image and the mirror frame are in focus.