The $400 Viltrox 85mm F1.8 lens is a popular choice for Sony E and Fujifilm X users due to its compelling blend of performance and value. Owners have remarked that the lens delivers sharp image quality even when shot wide open. It now appears that wide open can be made even wider with a firmware update allowing the lens to become an F1.6 prime.

Photographer Stefan Malloch has published a video tutorial, seen below, which shows how to use the USB port on the lens to update the lens. This update allows the lens to open its aperture wider, changing the maximum aperture from F1.8 to F1.6. With a simple firmware update, you can get an extra one-third of a stop of light gathering capability.
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https://www.dpreview.com/news/1131219246/a-firmware-update-turns-the-viltrox-85mm-f1-8-lens-into-an-even-faster-f1-6-prime