7Artisans 15mm F4

Testing on Sony bodies found sharpness even across the frame from f/4 with no midzone dip, corners peaking around f/11, and very good close-range performance. Distortion is close to zero, lateral colour is low and easily removed, and coma is well controlled, which suits astrophotography.

The weaker points are vignetting of about 3 EV wide open, a slight green cast in the corners and ring flare that gets worse when stopped down to f/11-16. One tester's first copy was badly decentred, so sample variation is a concern. It is larger and heavier than rivals such as the NiSi 15mm f/4 and Laowa 14mm f/4.

Owners like the straight lines, the ability to use standard 77mm filters on an ultra-wide, the sunstars and the solid feel for the price. Astro shooters report clean stars into the corners.

Complaints include the size and weight compared with other 15mm f/4 primes, the lack of EXIF data, the 0.4m minimum focus, the corner colour cast and occasional decentred copies.