I am certainly no expert but all three look over exposed to me. Also I know there is a fundamental difference with FX and DX format cameras but wouldn't be appropriate to shoot the subject with the same lens, ISO, and aperture, varying the shutter speed to meet the same exposure based on the metering system of each camera. The metering system is also a performance parameter if each camera. However, I would think that each metering system is reasonably close to one another. Of course a tripod would keep the field of view and stationary mount the same for each.