When it comes to stills camera’s, I’ve always been a bit of a Canon fan.  The problem is, once you start buying serious lenses (and Canon make some seriously nice lenses), it gets very expensive to change camera format without a good reason.  However, I was recently forced to look again at the Panasonic GH4. With it’s light weight and internal 4K, it’s clearly a great option for hanging off my new drone, (well, until someone makes a nice gimbal for the new Sony Alpha A7R II).

And surprisingly, I’m learning to love the GH4 even when it’s not on the drone… I realise I’m late to the party, but the Panasonic really does shoot some lovely quality video.  Even with the latest Magic Lantern tweaks, most Canon DSLR’s struggle to compete with all the video functions provided on the GH4.  So I already knew I’d be buying a Speed Booster at some point,  just so I could enjoy those lovely Canon lenses on my new camera.  Then, a couple of weeks ago, Metabones announced a new Speed Booster for the GH4… and for once my timing couldn’t have been better.

One week later, here it is – the Metabones Canon EF Lens to Micro Four Thirds T Speed Booster XL 0.64x

Catchy title, but what’s the difference to the previous Speed Booster?  Well, this one is actually designed for the Panasonic Lumix DMC-GH4, and the important figure here is 0.64x.  When we compare the existing GH4’s crop factor to 35mm full frame cameras, it’s 2x for HD video and 2.34x when shooting 4K.  The new Speed Booster XL reduces that crop factor by 0.64x, making it 1.28x in HD and 1.5x in 4K mode… and everyone who shoots S35 cine format, will recognise a crop factor of 1.5x

As an added benefit, the speed of any lens used with the Speed Booster XL is increased by 1 1/3 stops.  For example, a 24-105mm f/4 zoom actually becomes a very solid f/2.5, and if you have any f/1.2 lenses, they will work as an incredible f/0.8


I don’t mind admitting, I sometimes find the maths involved here confusing.  When I’m out shooting video I tend to think of all my lenses in S35 mode, so crop factors are pretty irrelevant to me. I just know what a 50mm lens looks like on my F5, without needing to compare it to a full frame sensor. However, put that same lens on a GH4 with a 0.64x Speed Booster, and how would it look?

On paper, a 50mm lens on the full frame Canon 5D should have the same field of view on S35 as a 75mm lens (or the GH4 in 4K with a 0.64x Speed Booster) and, on the Sony F5, roughly similar to an 80mm lens.  I needed to record a couple of tests… and these are included below.

On the first video, I’m using the same 50mm f/1.8 lens on my Canon 5D, Panasonic GH4 (in HD & 4K) and Sony F5. This was mainly to confirm what I expected to see with respect to angle of view on the different sized sensors. I’m sure I could have recorded this more accurately but it was pretty much what I expected. (ISO 800 on all three camera’s)

In example 2 the Canon 24-105mm f/4 L lens was used on all three camera’s but the focal length was approximately adjusted to match.  The depth of field examples are also what I expected to see from the Speed Booster specs, but the important result is the GH4 (4K) at 44mm f/2.5 compared to the F5 at 40mm f/4.  (The F5 sensor is slightly smaller than S35 with a crop factor of 1.6). Because the Speed Booster gives you that extra 1 1/3 stops available from the lens, it’s certainly possible to get a very close match in depth of field between these camera’s.

SpeedboosterF5 SpeedboosterGH4

As well as the cine 1.5x crop and 1 1/3rd extra stops of light, the Speed Booster also gives the GH4 full electronic control over EF lenses. That’s iris, lens readings and even image stabilisation exactly where you’d expect to find them on the Panasonic. The only thing missing is Auto Focus, which is no great loss in video mode anyway.  All my EF lenses appear to work correctly, although EF-S will probably vignette on 1.28x HD mode. In 4K mode, even my very wide Sigma 8-16mm HSM works well… if you really need to see your ears in shot!

I’m extremely happy with the Metabones Canon EF Lens to Micro Four Thirds T Speed Booster XL 0.64x… despite the long name!

Far from degrading the image, I actually prefer the video picture quality on the GH4 with the Speed Booster fitted. The Canon lenses give quite a cinematic look to what can sometimes be an overly edgy image from the GH4 and I’m pleased to say this makes a very usable ‘B’ camera to my F5.

Who’d have thought we’d be comparing depth of field on a 4/3rds sensor – happy days.



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