| With a teleconverter, you pull the light rays so far apart that the focal point, and thus the image on the sensor, becomes larger. The greatest advantage of a teleconverter is that a relatively small tool enables you to bring a distant subject closer to you. Disadvantages of a teleconverter are that the lens becomes less bright and that lens flaws become greater. A bad converter makes the image visibly less sharp. |
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And if you do the exact opposite? With a “Speed Booster,” instead of a teleconverter, instead of the magnifying the light rays, you compress them? So that—a wet dream for many videographers—the crop factor of a camera with a small sensor becomes smaller (1.4 instead of 2 for micro-43)? What you need is a mirrorless system camera and a lens that is designed for an SLR camera with a larger sensor. You thus have the space to place a Metabones Speed Booster between camera and lens. If you use a lens that is designed for a camera with a full-frame sensor on a system camera with a smaller APS-C or micro-43 sensor, you reduce the vignetting on the edges. Lens flaws of the original lens will be made smaller and more light also falls on the sensor, so that you can choose a shorter shutter time when there is low light. A 24 mm f/1.4 full-frame lens becomes a 35 mm f/0.95 lens on a micro-43 camera, with—in theory—a higher image quality than the original! It seems too good to be true. And just as with a teleconverter, the lens quality of the Speed Booster determines the ultimate image quality.
How does a Speed Booster work? It puts a lens (“Focal Reducer”) between lens and camera that makes the focal distance of the lens smaller. A smaller image (“Reduced Image”) results than with the use of the lens without a Speed Booster (“Original Image”). Because more light falls on a smaller surface, the lens with Speed Booster is brighter than without it. |
Metabones Speed Booster options:
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 Metabones Speed Booster is designed in such a way that an APS-C/DX lens can be used on a camera with a micro-43 sensor, without the creation of extra vignetting. That has the consequence that with use of a full-frame/FX lens on a Speed Booster, only the center of the image will be used by the micro-43 sensor. Full-frame lenses with visible vignetting when used on a camera with a full-frame sensor show much less vignetting with the use of a Speed Booster on a micro-43 camera. | |
Metabones Speed Booster: separate version for Olympus cameras | |
Metabones delivers Speed Boosters for 50 different lens/camera combinations (such as, for example, Nikon G, Leica M or Canon EF lens to micro-43 camera or Sony NEX camera). Sometimes, EXIF information (focal distance, aperture, zoom range) from the lens can be transferred to the camera. That makes it possible to set the aperture with the camera. Sometimes, that is not possible, and the Metabones Speed Booster has an extra aperture ring. Because there are so many different models, there is not a set price for all Metabones Speed Boosters. The higher the price of a Metabones Speed Booster, the more options you have. For our review, we chose a Canon EF to Micro Four Thirds Speed Booster S Version (MB_SPEF-m43-BM2), which can also be used on an Olympus camera. A previous version (MB_SPEF-m43-BM1) did not physically appear to fit on an Olympus OM-D E-M1, after which Metabones released the S version. | |
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Design, build quality and ergonomics | |
The Metabones Speed Booster is delivered in a hard plastic box. With the use of a converter, it is important that the lens remain perfectly aligned with respect to the sensor. A little bit of play in the connection between lens and converter, or camera and converter, can have disastrous consequences for the image quality. But the Metabones Speed Booster (“made of brass, precision-machined and plated with chromium”) is exceptionally solidly put together, and there is no play at all between adapter, lens and camera. The Speed Booster is about the same size and weight as a 1.4x teleconverter and is also fitted with a tripod foot (“detachable and compatible with Arca Swiss, Markins and Photo Clam ball heads”). The information transfer from lens to camera is not perfect. For less bright lenses (>f/1.8), the brightness will be automatically converted, so that you see the correct EXIF information on the camera: A Sigma 18-35 mm f/1.8 is changed by the Metabones Speed Booster into a 25-50 mm f/1.0. If, however, you use a brighter lens, like a Canon EF 85/1.2L with a Speed Booster on a micro-43 camera, then that produces a 121 mm f/0.74, but the camera still show f/1.2 as the largest aperture. For bright lenses, you thus have to underexpose manually by 1 stop. Metabones reports that image stabilization that is built in for Canon EF lenses still works with the use of the Micro Four Thirds Speed Booster S Version. But you do not have AF available. |
Metabones Speed Booster on micro-43: 24 mm f/1.4 becomes 35 mm f/0.95 |
High center sharpness and full-frame bokeh on micro-43 | |
| We reviewed the Metabones Speed Booster with a Sigma 150-600 mm Sports telephoto lens (Unbelievable! More later.) and with two bright wide-angle lenses (Canon 24 mm f/1.4L II and Sigma 24 mm f/1.4). The combination of a Metabones Speed Booster with a bright wide-angle is a favorite of videographers because it provides a bright 35 mm documentary lens, with which you can play with bokeh in a way unknown for a micro-43. The shots below are made with the Canon 24 mm f/1.4 L II, at full aperture, an Olympus OM-D E-M1. The second photo, of our bokeh test set-up, shows that at f/2.8, the angular edges of the aperture become visible, but that you still have a beautiful bokeh available. I realize that these are not very artistic shots. In the list with reviews, you will find sufficient image material with a higher level of artistry. | |
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| Next to the bokeh, we also tested other image quality properties of the Metabones Speed Booster, such as sharpness. From the practice shots of buildings, we immediately saw that the sharpness in the corners is nothing to write home about when you combine a wide-angle lens with the Metabones Speed Booster. Imatest measurements were carried out with the sharpest of the two lenses that we had available (Sigma 24 mm f/1.4 Art). As far as vignetting and distortion are concerned, the Metabones Speed Booster delivers what you expect: in comparison with the results on a camera with a full-frame sensor, the performance of this very good lens becomes even better. Nonetheless, both the Canon and the Sigma still show visible vignetting through f/2. The center sharpness is also very high starting at full aperture. The sharpness on the edges and in the corners is another story. The Sigma 24 mm f/1.4 Art changes from a modern, top-class lens with high sharpness in the corners into a vintage lens with characteristic blur on the edges. You actually have to stop down two stops (not unheard-of for an f/0.95 lens) before the corner sharpness has become sufficiently high. | |
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| Look in our list of reviewed lenses to compare the performance of the Metabones Speed Booster with a Sigma 24 mm f/1.4 Art (35 mm @ FF) on an Olympus OM-D E-M1 with other lenses. |
Metabones Speed Booster with a Sigma 150-600 mm f/5.6-6.3 Sports telephoto zoom |
With a very good telephoto lens (Sigma 150-600 mm Sports), the advantages that you can achieve in theory with the Metabones Speed Booster become reality. We reviewed the combination of a Sigma 150-600 mm Sports, Metabones Speed Booster with an Olympus OM-D E-M1 (photo) and Panasonic GH4 (photo and video). Both the practice shots and the Imatest measurement results from the Metabones Speed Booster with the Sigma 150-600 mm Sports were fantastically good. Only at full aperture did we see a difference in performance between the zoom lens with and without Metabones Speed Booster. Without Metabones Speed Booster, the highest sharpness was achieved starting at full aperture. With Metabones Speed Booster, the resolution in the corners clearly decreased after stopping down 1 stop. | |
 Razor-sharp with a butter-soft bokehPanasonic GH4 + Sigma 150-600 mm Sports + Metabones Speed Booster @ 850 mm (full-frame equivalent) f/4, 200 ISO, 1/800 sec | |
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Look in our list of reviewed lenses in order to compare the performance of the Metabones Speed Booster with a Sigma 150-600 mm f/5.6-6.3 Sports (200 mm & 800 mm @ FF) on an Olympus OM-D E-M1 with other lenses.. At full aperture, the center sharpness of the Sigma 150-600 mm Sports with Metabones Speed Booster is already very high. With stopping down 1 stop, the sharpness in the corners is also very good. Distortion and vignetting are practically absent, as it appears from our Imatest measurements. Look in our list of reviewed lenses in order to compare the performance of the Metabones Speed Booster with Sigma 150-600 mm f/5.6-6.3 Sports (only tested at the extreme focal distances—200 and 800 mm converted to full-frame equivalent) on an Olympus OM-D E-M1 with other lenses. | |
Video | |
| The Metabones Speed Booster, in combination with a good telephoto zoom, provides a bright telephoto lens with very high image quality. Here, you see a test shot that I made in the bird-watching hut at the Lepelaarsplassen, Almere, with a Sigma 150-600 mm Sports + Panasonic GH4 + Metabones Speed Booster, at the longest focal distance and the aperture fully open. Given the focal depth and the bokeh, the image quality (sharpness, absence of distortion and chromatic aberration) correspond with a shot that you would make with an 850 mm f/4 lens on a camera with a full-frame sensor. As far as the absence of vignetting is concerned, the Metabones/Sigma combination scores even better. | |
Panasonic cameras offer the option of using an “Extra Tele Conversion (ETC) mode” for Full HD (1980 x 1080 pixels) video recordings, where only the pixels in the center of the image will be used for the video recording. With this, you create an extra crop factor of 2.5, on top of the usual crop factor of 2 for micro-43. The Sigma 600 mm f/6.3, Metabones Speed Booster and Panasonic GH4 (GH3), with the use of the ETC mode, produce video recordings with the same brightness and field of view as a 2,000 mm f/4.0 lens. |  |
Conclusion Metabones Speed Booster S (micro-43) reviewLook in our list of reviewed lenses in order to compare the performance of the Metabones Speed Booster with a Sigma 24 mm f/1.4 Art (35 mm @ FF) or a Sigma 150-600 mm f/5.6-6.3 Sports (200 mm & 800 mm @ FF) on an Olympus OM-D E-M1 with other lenses. |
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Pros
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The Metabones Speed Booster is a wet dream for almost every videographer and many photographers. A bright, full-frame wide-angle lens changes into an ultra-bright standard lens for micro-43 or APS-C (Sony E-mount, Fujifilm), with a very high center sharpness and unparalleled bokeh. An investment of a couple hundred euros changes a full-frame telephoto lens into a telephoto lens for micro-43 or APS-C with a brightness that you expect from telephoto lenses of more than 10,000 euros. That you can then only focus manually is no problem at all for most videographers. The Sigma 150-600 mm Sports with Metabones Speed Booster is convincing, with an unparalleled brightness and sublime image quality on both an Olympus OM-D E-M1 and a Panasonic GH4. With wide-angle lenses, you lose a great deal of sharpness at the edges, but the center sharpness is very high starting at full aperture, and the bokeh possibilities will make your mouth water. | |
