This week I found Adjustable Aperture Focal Reducer Speed Booster from Canon EF to micro 4/3 mount for sale on Chinese market. Is this adjustable aperture worth additional $1-$2 ? It is built into adapter and I counted 16 aperture blades. Can't find any review of this product yet. I have only M42 and m4/3 lenses so far. I can mount M42 lenses using additional M42-EOS adapter.