Quote Originally Posted by OldClicker View Post
Ed,

DT lens on an FF body: The DT lens has a smaller image circle than a lens designed for an FF body. This would show up as a dark vignette around the edges; especially the corners. How much vignette would depend on the focal length and the design of the lens. Some FF bodies (such as both of Sony’s) will automatically crop the image to APS-C size when it detects a DT lens. For instance the Sonys will crop the normal 24 Mpixel down to about an 11 Mpixel image with a smaller field of view.

Non-DT lens on an APS-C body: The image circle is larger than the sensor so the sensor just sees the center portion. The resulting image will be the same for both the DT and non-DT lens and the APS-C body.

If you have an APS-C body, you will never know the difference between the two other than DT lenses will tend to be smaller, lighter and cheaper than the same quality non-DT lens.

Terry
Terry,

Thank-You for the "in-depth" explanation, that helps me understand it more clearer now..

Ed