September 17, 2014 at 4:57PM


EF to Micro four thirds Speed Booster Differences

Hey all,

After purchasing my pocket camera and looking into a GH4 I'd love a "one mount fix all" solution when buying a an EF to M43 speed booster.

So question is, is there a difference between the

"Canon EF Lens to BMPCC Speed Booster"


"Canon EF Lens to Micro Four Thirds Speed Booster"

Other than the extra $60 of the pocket camera version.

Ideally i'd buy the regular EF to m43 and have it work on both my GH4 and Pocket camera? Am I missing something?


i tried both and if you look at the specs they are different.

gh4 is a mft size sensor with a mft size mount
bmpcc is a smaller siz sensor with a mft size mount.

in photo 35mm full frame terms

for the gh4 a 25mm lens would emulate a 50mm ff sensor with a 2x crop factor.
for the bmpcc a 25mm lens would emulate a 75mm ff sensor with a 2.5 times crop.

the depth of field and sensor size is significantly smaller for the pocket camera.
you would need like a 14mm lens to emulate something close to a 50mm. But a 14mm lens is close to and almost a fisheye. you would get heavy distortions.

the regular mft speedbooster will get your gh4 fov close to a super 35mm
on a bmpcc, the speedbooster will not extend your fov enough to make it a super 35mm
the bmpcc mft speedbooster is designed to get the bmpcc's very small sensor close to super 35mm.
also the bmpcc's sensor/glass distance is very short.
the bmpcc speedbooster will not work on the gh4.
you can also NOT use an adapter on top of the EF mount.
i tried my EF mount duclos contax zeiss with leitax conversion lens and it will not fit.
also tried a ZF converted zeiss with a nikon g to ef adapter on top of the bmpcc and it will not work.
you have to get a nikon to mft for that.
there is a flange that blocks against the small mount.
you will damage/scratch your adapter and break it if you use another adapter on top of the bmpcc speed booster.
im not sure about the regular mft speed booster.
but with the bmpcc speed booster you cannot double convert with adapters.

also it eats battery life like a mule if you use a canon branded electronically controlled lens.
consider the battery life about half.
i had 4 fully charged batteries and got just over 1.5 hours of record time in raw

October 5, 2014 at 1:59PM

Kazu Okuda

Its not so complicated. The Speedbooster "Canon EF Lens to Micro Four Thirds Speed Booster" is what the name says. It's for all MFT-mounts. The differences of how much wider it makes lenses and how much the aperture is increased you can see at Metabones.
BMPCC Speedbooster: 1⅔ stop, 0.58x wider
MFT Speedbooster: 1⅓ stop, 0,71 wider
I think you'll be happier with the "Canon EF Lens to Micro Four Thirds Speed Booster" because it fits on both, BMPCC and GH4.

January 6, 2015 at 10:58PM

Lutz Leonhardt

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