Hello everyone, we have made the first prototype of format extender (the adapter) to eliminate vignetting.
The 2 elements design is enough to enlarge the image field to cover the instax mini film. But the max distortion ratio is up to 17%. We have tested 35mm, 50mm and 135 mm lenses and all of them could function well in their original focus range.
The adapter causes loss of 2 stops aperture.
We have began to optimize the adapter with extra element to decrease the max distortion. We are also eager to listen your voice and insights about the distortion in our Facebook group community, especially your acceptable max distortion for instax films.
Here are some samples for your refence.