Motor On wrote:
The camera system a lot of times will attempt to keep 1/focal length for the shutter speed; with a crop camera the camera will try to keep 1/(1.6xfocal length). This is to prevent motion blur from hand movement.
raptor3x wrote in post #17488194
If you use the same focal length in Av both on both a crop and ff Canon body, the shutter speed chosen by the crop body will be ~1.6x faster than on the ff body to try to reduce blur due to camera shake. This is only a function of the Av logic
compensating for narrower field of view (and thus greater sensitivity to camera shake) on the crop body compared to the fullframe body.
1. There is no camera which has the logic built into its 'shutter speed = FL/1.6' rule of thumb... That is a rule of thumb for the PHOTOGRAPHER to apply! A meter is a meter, and has no idea of the size of the camera's sensor or film, so has no clue as to any rule of thumb about camera motion and allowable shutter speed for handholding.
2. The same FL on APS-C vs. FF will result in a narrower Field of View on the APS-C camera, due it is 1.6x smaller sensor.
If the metering systems of both cameras measures the frame content of both frames while using identical FL and same camera position,
- the APS-C meter MIGHT read different reading than FF meter, merely because the frame areas read varies naturally between the two cameras, and the brighter, outer area at the edges of the frame can result in a faster shutter speed
- But if both cameras were pointed at the same blank uniformly lit wall, the meters should measure the SAME shutter speed with the same aperture, in spite of difference of FOV.
To illustrate how framing changes metering, here are two shots with the same camera with the same position, but with different areas framed (shot 2 FL is about FL/1.6 compared to shot 1!)
The shot on the left meters 1/60, the shot on the right meters 1/80 !