Venus Optics says it managed this by taking advantage of the short flange distance of mirrorless cameras and employing a new optics system that can expand the image circle of the lens without harming image quality.
As such, the Laowa Magic Format Converter boasts a focal length multiplier of 1.4x, which helps it fill the larger image circle of the GFX 50S. However, it reduces the maximum aperture by 1-stop.
Venus Optics says the Magic Format Converter will be most useful for photographers shooting with ultra-wide angle lenses, as GFX users will be able to enjoy an ultra-wide angle without having to crop away unusable corners of the images.
As an example, Venus Optics says that when the Magic Format Converter is used with the Laowa 12mm f/2.8 Zero-D lens it will become a roughly 17mm f/4 lens in GFX-50S. The angle of view will be around 116° (equivalent to approximately a 13mm lens in 35mm format), making it one of the widest lens available for the GFX system.
The Magic Format Converter is Laowa’s second converter of this type, having launched the Magic Shift Converter last year, which can expand the image circle of full-frame lenses and convert them into shift lenses for use with Sony Full Frame E-mount cameras.