Re: Jason Somes - CAF Bearcat
I really strongly believe it ia a combination of motion and, depending on aperture, some DOF. You won't get much edge fall off with a telephoto, and especialy not with those big Cannon L glass primes. Mike Arnold has it right, The planes are moving a lot while the shutter is open. If you track the relative motion of the camera imaging chip and the aircraft, in 3/4 views the aircaft's orientation chages while the shutter is open. In a slow exposure, the lead shutter curtain is fully open before the trailing curtain starts to close. This allows time for motion blur. On a fast shutter speed, there is only a stripe of open shutter running across the chip, so each spot along the chip only gets a very brief look.
If anyone has seen those old auto racing photos from the teens, there were often dramatic images in which the car appeared to be leaning forward, This happened because the shutter travelled verticaly, and only exposed a portion of the film at any one time. By the time the slit traveled from bottom to top, the car had moved forward relative to the camera.
Another bit of proof the blur has a large element of motion to it is the prop itself. The prop is not blurry because of DOF, its blurred because of its motion relative to the open sensor. The tip of the spinner is sharp because its not moving relative to the sensor. Other portions of the airplane are going through the same process. While the shutter is open, some parts of the plane happen to be moving relative to the sensor, and some are not. Kind of like the prop spinner, in each photo there is a central point around which the rest of the image is in motion.
Look through all of your outtake photos, and sometimes you will spot an image where one prop blade is sharp, and all the rest of the plane is blurry. This is not because of DOF, but rather once again, a question of relative motion during the exposure.
Dang, I need a
I really strongly believe it ia a combination of motion and, depending on aperture, some DOF. You won't get much edge fall off with a telephoto, and especialy not with those big Cannon L glass primes. Mike Arnold has it right, The planes are moving a lot while the shutter is open. If you track the relative motion of the camera imaging chip and the aircraft, in 3/4 views the aircaft's orientation chages while the shutter is open. In a slow exposure, the lead shutter curtain is fully open before the trailing curtain starts to close. This allows time for motion blur. On a fast shutter speed, there is only a stripe of open shutter running across the chip, so each spot along the chip only gets a very brief look.
If anyone has seen those old auto racing photos from the teens, there were often dramatic images in which the car appeared to be leaning forward, This happened because the shutter travelled verticaly, and only exposed a portion of the film at any one time. By the time the slit traveled from bottom to top, the car had moved forward relative to the camera.
Another bit of proof the blur has a large element of motion to it is the prop itself. The prop is not blurry because of DOF, its blurred because of its motion relative to the open sensor. The tip of the spinner is sharp because its not moving relative to the sensor. Other portions of the airplane are going through the same process. While the shutter is open, some parts of the plane happen to be moving relative to the sensor, and some are not. Kind of like the prop spinner, in each photo there is a central point around which the rest of the image is in motion.
Look through all of your outtake photos, and sometimes you will spot an image where one prop blade is sharp, and all the rest of the plane is blurry. This is not because of DOF, but rather once again, a question of relative motion during the exposure.
Dang, I need a
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