Laowa 105mm f/2 (T3.2) STF – Testing
Our Applied Imaging tests tell us the centre is only slightly sharper than the corner when the lens is used at f/2. Centre sharpness improves as the lens is closed down towards f/4 and remains high up to f/16. Diffraction affects the level of sharpness at f/22, hence the drop on the graph. Corner sharpness improves when the lens is stopped down to f/8. Like the centre sharpness, though, it drops off at f/22. The sweet spot between centre and edge sharpness is located between f/5.6 and f/8.
Using the lens at its maximum aperture introduces corner shading at the edges, with corners appearing approximately 1.2EV darker than the centre of the image. I found this vignetting to be rather tasteful and it encourages the viewer’s eye towards the centre of the image. Stopping the lens down to f/4 sees corners appear 0.6EV darker than the centre.
Telephoto prime lenses have a reputation for controlling curvilinear distortion better than zooms. This Laowa optic rendered the horizontal and vertical lines perfectly straight on our test chart, saving us time having to correct for any barrel or pincushion distortion in our software.