Page 10 - Learning How to Photograph with your DSLR Camera 2nd Edition Jan 2021

APS-C lenses

The APS-C lenses have the same nomenclature as the full frame format lenses. A 35
mm APS-C lens is also a 35 mm on a full frame and vice versa. A significant difference
is the lens rear opening is smaller on an APS-C lens to accommodate the smaller sensor.
The full frame lens has a larger opening and any light passing through it will cover the
entire sensor on a APS-C camera body. An APS-C lens by virtue of having a smaller
lens opening will not cover the entire sensor on a full frame format camera body. This
leaves the corners of your images very dark and cutoff. Fortunately, most full frame
camera bodies recognize a crop sensor lens on your camera and will automatically crop
the frame, so the image is not cut off and having very dark corners. This lens correction
lets you use your APS-C lens even on a full frame, though the field of view will not be the
same. *I do not use APS-C lens on my Full Frame cameras; however, I will use my Full
Frame lenses on my DX/APS-C bodies.

Figure 2 APS-C lens on a Full Frame Camera and an APS-C Camera.

*Note the black corners on the Full Frame Sensor as the APS-C lens opening (blue circle) does not cover the sensor completely.

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