The SOONWELL B4 2/3″ Lens to Canon EF Adapter Mount Ring allows you to mount broadcast-style B4 2/3″ lenses on EF-mount cameras like the Canon C300 Mark III, Canon C200, Panasonic EVA-1, Blackmagic Design Pocket Cinema Cameras, etc.
Older 2/3″ B4 lenses are pretty affordable these days, but they were never designed for use with CMOS sensor cameras. While they can certainly offer a very good focal range, they can produce strong chromatic aberration and other optical issues when used on some of today’s modern cameras.
Now, what you need to be clearly aware of is this is a simple adapter that doesn’t feature any optics. Without any optics, no 2/3″ lenses will cover an APS-C sensor, even if you use a 2x extender, especially at wider focal lengths.
Key features
- Use a B4-Mount Lens on EF-Mount Camera
- Designed for Canon EOS Cameras
- Aluminum Alloy Construction
- Screw Set Included
According to Soonwell, you need to use an optional Kenko (not Canon) 2x extender for it to work. Only on the telephoto side (130mm and up) and when using the 2x extenders will you be able to get images without vignetting.
The other problem is because there is no power being supplied to the lens you won’t be able to use the servo zoom. The only way to power the lens if you want to use the servo would be to hook it up to a portable power supply that utilizes the correct cable interface.
These B4 2/3″ Lens to Canon EF Adapter Mount adapters that don’t feature any optics are very niche products and probably not worth the effort in 2023.
Price & Availability
The SOONWELL B4 2/3″ Lens to Canon EF Adapter Mount Ring retails for $139 USD.
