Test Results: Shading and Distortion
Shading
Our tests show that vignetting is quite severe at both 24mm and 240mm, although it’s much lower in the middle of the range. Obviously, it is easily reduced and removed in Camera Raw or similar software. Indeed, if in-camera compensation is enabled, it will be removed almost completely from JPEGs. However, if you don’t correct for distortion at wideangle in raw images, you’ll still see darkening in the extreme corners of the frame.
Distortion
The 24-240mm is designed around software corrections, and camera JPEGs are essentially free of any distortion. However, in raw files barrel distortion is present until about 50mm, beyond which it turns to pincushion. Correcting this distortion is easily done, but the slight stretching of the image doesn’t help the sharpness.