In a recent article by Jaron Schneider about the Metabones Speedbooster on a Black Magic Pocket Cinema Camera, several readers had questions about the model designed for the GH4, whether this one would work with it or not, and other comments. I bought one of these a week ago and wrote this article to tell you what works, and what doesn’t.

There are several different lens adapters that Metabones makes. Some not only adapt to fit lenses but alter the recorded image by increasing exposure and the field of view. For the sake of explanation here are the three particular models that have been discussed recently in Jaron’s aforementioned article comments, and will be noted further below.

Canon EF Lens to BMPCC (Black Magic Pocket Camera) Speed Booster BH | Metabones Canon EF Lens to MFT (Micro Four Thirds) Smart Adapter BH | Metabones Canon EF Lens to MFT (Micro Four Thirds) Speedbooster BH | Metabones

Around the web, people seem to be using the MFT models primarily for the Panasonic GH4 and GH3, but unless otherwise noted by Metabones, they can work on other MFT mount cameras.

What makes this a little confusing is that the BMPCC is an MFT camera. The difference is that with the BMPCC version, the adapter has been configured to work with BMPCC specifically. If you attempt to use that adapter on the GH4 for example, you will get an error (according to this Phillip Bloom article) and some report that if you screw your glass forward to fit it, you will break the focus (comments section of this video.) The short story is this: It's not recommended and likely won't work. The great thing is that now you don't have to even try since there is an adapter specificially for the GH4.

To add some more confusion into the mix, there were reports on EOSHD of the BMCC model of adapter (WHICH IS NOT THE POCKET CAMERA ADAPTER) being used on a GH4 with a Nikon lens. My guess is that some readers mistook BMCC for BMPCC when reading, or assumed that if an adapter worked for one, it would work for the other?

In any case, Metabones has available an "MFT" adapter, which is absolutely meant for the GH4.

There are two versions, a smart adapter and a speed booster. They are mostly the same except the speed booster will increase the sensitivity of your lens by 1 stop, and make the effective focal length about .71x wider. There are a lot of other details that you can read about right here on the Metabones web pages for either the Smart Adapter or the Speed Booster.

I got myself the Canon MFT Speedbooster to use on my GH4, and below I'll note some of the lenses I've used it with. I'll also include the approximate calculations for what a lens range becomes on the GH4 with the Speedbooster, as well as their approximate full frame equivalent focal lengths. If you'd like to do the math yourself on a lens you own, multiply the adapter FOV reduction (.71) by the focal length of your lens. This gives you the focal range of the lens on the GH4. If you want to know the approximate full frame equivalent, just double that number.

Canon 24-70L f2.8 II becomes a 17-50mm f2.0 on the GH4, or 34-100mm f2.0 FFE

Canon 70-200L f2.8 IS becomes a 50-142mm f2.0 on the GH4, or 100-284mm f2.0 FFE. The IS was functional.

Canon 16-35L F2.8 II becomes a 11-25mm f2.0 on the GH4, or 22-50mm f2.0 FFE

(no image, but tested and it works)

Sigma 15mm f2.8 becomes a 11mm f2.0 on the GH4, or 22mm f2.0 FFE

Sigma 17-50mm IS f2.8 becomes a 12-35.5mm f2.0 on the GH4, or 24-71mm f2.0 FFE. The IS was functional.

Sigma 10-20mm f4-5.6 becomes a 7-14mm f2.8-4 on the GH4, or 14-28mm f2.8-4 FFE

Rokinon 16mm T2.2 becomes a 11mm T1.6 on the GH4, or 22mm T1.6 FFE

Rokinon 35mm T1.5 becomes a 25mm T1.1 on the GH4, or 50mm T1.1 FFE

All lenses I tested worked, but the Rokinon lenses were not recognized by the camera. This was easily bypassed with a simple menu command, then they worked. There was no communication between the lens and the camera, and lens EXIF data was not recorded either.

The aperture displayed f0.0, which is what happens when these Rokinon Cine Lenses are used on Canon bodies since they are manual aperture lenses. Additionally, as far as I could tell, these lenses did NOT damage the adapter, but Metabones warms that some MF lenses can harm it. Try third party manual focus lenses at your own risk, and do your research online before doing something that might damage your kit. Metabones does have tech support, so you can reach out to them if you have specific questions about a particular lens, or what to look for in a lens that might damage the adapter.

Some thoughts about the lens/adapter combinations

It's very interesting to look at the stats from lenses with the adapter, and compare them to the standard lenses you might normally use with the GH4.

For example, the Sigma 10-20mm was very wide at 10mm, and right now the widest lens available for the GH4 (that I could find) is a Panasonic Lumix 7-14 f4, and it cost me almost twice what I paid for that Sigma lens, many years ago. It makes me want to do some lens tests to see if the quality of the Sigma holds up, because if it does, it is a stop faster than the Lumix lens and would make it my go-to wide angle when weight isn't a concern.

Now look at the Sigma 17-50 f2.8 IS. My go-to lens for the GH4 is the 12-35mm f2.8 IS, which is a solid little lens. But with the Sigma and speedbooster combo, I get effectively the same FFE focal range (24-70ish) but I get another stop of light to work with.

Of course the catch is that you lose AF ability by using the adapter. Honestly I don't miss it, I'm very used to using manual focus (for video) so much that it is not an issue for me, so remember that before you take the plunge on the adapter yourself. I hope these finding were helpful to you. I can't test it with lenses I don't have, but I'm happy to answer any other burning questions your may think of. Leave a comment below!