Viltrox AF 28mm F4.5 FE

Reviewers judge the image quality acceptable to good for the size and price. Centre detail is fine for everyday shooting, lateral CA is low, and distortion is minor. Contrast and corner resolution trail Sony's compact G primes, and there is heavy vignetting of almost 3 EV, sometimes with a blue corner cast.

Autofocus is quick in good light but can be blunt in dim conditions, and there is no manual focus override. Flare from light sources just outside the frame can be severe, though it still compares well with other pancakes.

Owners love how small it makes an A7C or A7 body and many call it the most fun lens they own at $99. The built-in cap and the eight-point sunstars come up often.

The quirks are the fixed f/4.5 aperture, no filter thread, the need to open the cap before powering on, a loose rattle from the focus group when the camera is off, and slow focusing at night.