Lens Reviews Help
This shows how the lens’s illumination falls off towards the edge of the frame. For easier visualization the display is posterized in third-stop steps, and you can choose whether or not to display the values of these rings. The shades of grey used are derived from the actual image file analyzed, and so represent accurately the magnitude of the falloff; because the initial third-stop is essentially imperceptible to the human eye, we have removed it to simplify the graphic. The central 'dpreview.com' logo is displayed at the actual brightness level of the extreme corners, giving an additional indication of overall falloff.
As usual you have focal length and aperture dials which can be controlled using either the mouse or the cursor keys. Data is measured at each marked focal length on the lens, and at all apertures in third-stop increments down to F11 (at which point falloff has all but disappeared from most lenses).
Falloff – shows the maximum falloff value at the far corners of the image
Show values – allows you to show/hide the falloff values on the main display