Last week, a whirlwind of interest circled around a new adapter announced by Metabones, the Speed Booster.
Mount adapters are very common these days, especially for those who use DSLRs or mirrorless cameras for video shooting with various Nikkor, Zeiss or Canon lenses on different bodies. I, for example, use a Panasonic AF-101 (micro four thirds mount) with a Novoflex adapter and my Nikkor lenses. One of the things you need to be aware of is that mounting a full frame (24 x 36) lens on a camera with a smaller sensor will increase your focal length. A 24mm full frame lens is a 48mm equivalent on a micro four thirds sensor, and a 36mm equivalent on an APS-C sensor. This can be a limitation especially for wide-angle lenses. If I need to capture a very wide shot with my Panasonic AF-101, I use the excellent Lumix 7-14mm f/4 or the Tokina 11-16mm f/2.8. Beyond these two models, there aren’t many alternatives out there.
What is interesting about the new Speed Booster adaptor is that it allows you to keep the focal length of your full frame lens relatively wide on a smaller sensor. But how it works? Let’s me introduce you some history aspect first.
Since the introduction of the digital reflex, photographers have been fully aware of the possibility of using full frame lenses on smaller sensors. The first DSLR only had an APS-C or DX sensor, smaller than the standard 24×36 frame you find with film. As such, every lens had a 1.5 crop factor, unless the lens was specifically designed for that smaller sensor.
Then, the first digital full-frame SLRs came along, and professionals rediscovered the focal length they knew and loved before digital. But while full-frame DSLRs are very common these days, they aren’t cheap and most people use APS-C or DX cameras like the Canon 7D or the Nikon D7000. Many wonder why it isn’t possible to create an adaptor that maintains the focal length of a lens on the smaller sensor, knowing that this sort of accessory exists for telescopes (the focal reducer). The answer is simple: the mirror inside the DSLR body makes it impossible to create such an adapter.
That’s where mirrorless camera enter the game: the absence of a mirror reduces the distance between the sensor and the lens (approximately half the distance) and makes it possible to built an adapter.
Metabones accepted the challenge to create such an adapter, and the result was the Speed Booster, an adapter that reduces your focal length by 0.71. A 24mm designed for a full-frame sensor will thus remain the equivalent of a 24mm on an APS-C sensor. But that’s not all: by narrowing the image circle of full-frame lenses, this adapter can also increase the speed of the lenses. So, if you are using a 24mm f/2.8, it becomes a 24mm f/2. Not bad at all!
This adapter is available for Sony Nex e-mounts, Canon Eos M mounts, micro four thirds mount and Fuji X mounts. Autofocus is usable but has some limitations. You can find more information on the Metabones website.
Personally, I consider this adaptor more useful for videomakers who like to use Sony Nexes or professional camcorders like the Sony FS700 or the Panasonic AF-101. However, for those who like to experiment with different lenses on their camera, it could be an attractive accessory. It isn’t cheap though – the price will be around $600.
If you want a more technical explanation regarding its inner workings, Metabones provides a very interesting PDF file to read. You can download it here.
There are also a few video tests you can see here.