There is a large selection of a adapters available for using lenses from many different mount systems on E mount cameras like the Sony NEX- or α-series. All adapters for E mount can be subdivided into four categories, which differ in their functionality:
- Mechanical without aperture control
- Mechanical with aperture control
- Electronic without AF
- Fully functional electronic
For each category, adapters may be available glass-less or equipped with optical elements. The most common adapters seen on NEX and α belong to category one. Examples for this category are the simple made in China adapters for NEX-Minolta SR usually found on eBay. Category 2 applies for most purely mechanical NEX-Minolta A adapters, as AF lenses typically offer no aperture control ring themselves. Examples for category three and four are the Sony adapters LA-EA2 and LA-EA4, although the LA-EA2 does offer contrast detect AF when the lens has it’s own focus motor.
Adapters for manual focus Minolta lenses
By design, all adapters for the Minolta SR mount (MC/MD) are of category 1: Plain pieces of aluminum with or without glass. The most common adapters are presented below, accompanied by some basic info. Some reviews are available in the reviews section of the site and tagged with the keyword “focal reducer”.
Metabones & Novoflex glassless adapter
Metabones is a US-based company specializing solely in adapters for camera systems. They offer purely mechanical adapters and adapters with electronics, both with and without optics. Metabones has a solid reputation amongst photo enthusiasts and offers a great variety of products. Their Speedbooster (see below) focal reducers are the best you can currently buy. But they don’t come cheap and you have to pay quite a bit more than for most no-name products.
Novoflex is a company based in Germany specializing in photo equipment. As such, they also offer various mechanical mount adapters “Made in Germany”, which are known to be of excellent build quality and fit. On the plus side, buying Novoflex adapters offers you peace of mind. On the minus side – as with Metabones – the price is considerably higher than that of no-name adapters.
Made in China glassless adapter
The cheapest adapters available come for about 10 € or $ directly from China. There are various versions in slightly different designs, but in the end, they are all made from a piece of anodized aluminum, some screws, a spring and a chrome-plated brass mounting plate. There are reports of more or less tight fitting mounts and the infinity focus can be off, so quality control seems to be questionable at first. But considering the hundred thousands of adapters that should be floating around, there are still comparatively few reports of such problems. Whilst a defect is very annoying if it happens to you, receiving a flawed adapter seems not very likely.
I know a handful of people who are using these adapters day and night and can recommend them. They may not be perfect, but they offer great value.
Metabones Speedbooster and Speedbooster Ultra (NEX only)
The Speedbooster is not only an adapter, but also a focal reducer. It reduces the focal length of your lens by a factor of 0.71, compensating for most of the cameras crop factor of 1.526, resulting in an effective crop factor of only 1.08. To learn more about focal reducers, have a look at the very informative explanation by Ruben Kremer. As the focal length reduction is equal to a reduction of the image circle diameter of the lens, the combination of Speedbooster and Minolta MC/MD lens does not cover the full frame anymore and is thus not suitable for any Sony α7-series or full frame NEX camera.
The first version of the Speedbooster was the first commercial focal reducer available for EVIL cameras. The optical quality is pretty solid and the mechanics keep up with it. The Speedbooster is available with electronics for lens mounts that feature AF. It is claimed to give slightly warmer colors than the Zhongyi Lens Turbo (see below), and has an ever so slight advantage in resolution compared to the Lens Turbo II. The latter, in contrast, offers better control of chromatic aberrations. Metabones improved the design of the Speedbooster with the second iteration, the Speedbooster Ultra. The new version achieves increased sharpness but is not available for Minolta MC/MD mount, yet.
Zhongyi Lens Turbo I and II (NEX only)
The Lens Turbo is – if you want to put it that way – the cheaper, non-electronic Chinese version of the Speedbooster. It reduces the focal length of your lens by a factor of 0.726, resulting in an effective crop factor of 1.11, which is actually quite a bit more tele than the Metabones Speedbooster. To learn more about focal reducers, have a look at the very informative explanation by Ruben Kremer. As with the Speedbooster, the image circle does not cover the full frame anymore when you use a Minolta MC/MD lens on a Lens Turbo.
The first version, sold without the ‘II’ in the name, had a common problem with a hazy blue dot appearing in the center of the frame in certain lighting conditions which is why I wouldn’t recommend it. The second version fixed that problem and is generally deemed to be a solid performer. I’ve seen comparisons with the Speedbooster (non-Ultra) where resolution was very close with the Lens Turbo II loosing by a hair but showing visibly less chromatic aberrations. The ‘Ultra’ version of the Speedbooster surpassed both of them in terms of resolution. The lens Turbo is claimed to give slightly cooler colors than the Metabones focal reducer.
Made in China focal reducer (NEX only)
You can find anything on eBay and no-name focal reducers are no exception. These really cheap knock-offs are mechanically and optically a gamble. While manufacturing good mechanical parts is no rocket science and requires little more than good machines, trained operators and quality control, designing and producing high quality optics is another level of complexity. Whilst I can recommend cheap mechanical adapters (see above), I would never recommend cheap focal reducers.