The "Ultra" is a new series of Speed Boosters with improved optical performance. These improvements are: 1) better corner performance (MTF); 2) reduced distortion; 3) reduced vignetting; 4) better performance with lenses having a long exit pupil distance, such as pro-grade f/2.8 zooms and ultra-high speed primes. In the outer ~30% of the circle you will see a significant improvement, especially wide open.
For now it's limited to Sony E and Fuji X - mount sensor size (in both Canon and Nikon), but more sizes coming soon.
Press release (pdf)
For now it's limited to Sony E and Fuji X - mount sensor size (in both Canon and Nikon), but more sizes coming soon.
Press release (pdf)
