Zeiss Batis 40mm f/2: Data Sheets Continue to Omit Optical Distortion, Showing Only Corrected Distortion
Get Zeiss Batis at B&H Photo.
I objected to this change in Zeiss data sheets some years back, and I reiterate it now: Zeiss data sheets no longer show uncorrected distortion (sin of omission) and show only a misleading corrected distortion graph (sin of irrelevance and contradiction vs MTF).
Zeiss is not alone in this misleading behavior. For example, Fujifilm X lenses require distortion correction (in Adobe Camera Raw) and the Leica Q has horrific barrel distortion which notable impaires MTF in outer zones. Other companies do it also.
- Correcting distortion can lead to a substantial drop in micro contrast in some areas of the frame (for example, the Batis 18mm f/2.8 is visibly inferior in the corners and mid-zones when corrected). If distortion is shown corrected by software, then why is MTF shown without distortion correction? The claimed MTF is not achievable with distortion correction enabled.
- I rarely correct distortion because I want the full optical performance. I’d like to know the actual optical behavior.
- What is the point of showing a corrected distortion graph, other than perhaps to mislead? Once corrected, the distortion is so close to zero as to render the exercise meaningless.