Viltrox has designed a 28mm pancake lens for mirrorless Sony cameras which, with a fixed aperture of F4.5, is neither very fast nor very flexible, but is extremely portable. The lens is only 15.3 mm long and weighs 60 grams.
Viltrox AF 28mm F4.5
The optical construction consists of six lenses, including 2 aspherical and 2 ED elements. An autofocus is also built in; this moves the entire lens construction when focusing, not just individual groups. According to Viltrox, the front shutter embedded in the lens must be opened before the camera is switched on in order for the automatic calibration of the autofocus to work, as the shutter apparently also fixes the lens groups. The closest focusing distance is 32cm.
Front shutter
Despite the shrunken construction, the lens is also suitable for full frame. However, it is not compatible with all Sony E-mount cameras and the autofocus does not work reliably with some models. If you find the lens interesting, you should study the 
compatibility list before buying.
The Viltrox AF 28mm F4.5 for Sony E-mount costs 109 euros and will be available for regular delivery from November. It was offered at a discount on Indiegogo before the launch, where you can also find an update on the special feature with autofocus and the front shutter.
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