It's no secret I love my Sony NEX mirrorless cameras and my using my Sony a99; Sony's flagship full frame, full bodied, camera. While they lack a few pro features that I like to have, the NEX series cameras have proven themselves worthy and easily match much larger cameras.
When Metabones came out with their Speedbooster, the internet buzzed with the possibilities of using full frame lenses on an APS-C sensor sized camera AND gain one stop in light gathering ability. The Canon EF adapter was, and is, by far the most popular but as I'd sold all of my Canon glass, I had to sit and wait for the Sony Alpha/Minolta mount version to come out.
Even once it was available I was a bit hesitant. I was afraid that my NEX-7 with a speed booster would leave my far more expensive a99 collecting dust! Eventually I took the plunge and ordered one as the reality is I don't rely on just one camera and if the NEX-7 were transformed into a mini-a99, that would suit me just fine!
It was right around the time that I received my Speedbooster, that I recieved my favourite lens back from repair...my Leica 50mm f/1.4 Summilux R. With the power of the Speedbooster, this lens collects light as if it were an F/1.0 lens!
Until yesterday I'd only played casually with the Speed Booster; getting a feel for how it works and how it impacts image quality. In casual use I've learned a few things which have led me to treat it like a teleconverter in reverse. Here's why I digress and get technical...you can skip to the photos at the end now if that's not your thing.
First, the Speed Booster amplifies light; the opposite of a teleconverter. This lets you take a fast lens and make it faster. This is the feature which gets the most press. I've discovered another use. At middle apertures, you can stop a lens down to a sharper aperture and not lose any speed. A lens which is good at f/2.8 and great at f/4 is still effectively an f/2.8 when you stop it down one stop...at least when it comes to light gathering. Combined with the shrunk image circle, you can increase effective sharpness of a lens dramatically (depending on the lens).
Depth of field is deceptive as it's not impacted by the Speed Booster. This is moot in a way as your field of view is no longer cropped but equivalent to a full frame camera with a full frame sensor so the perspective is different anyhow.
There are limitations to the Speed Booster as well. When used on a long telephoto lens, the exit pupil at the rear of the lens is larger than the Speed Booster can capture and the result is a hard vignette. Except for the light gathering boost granted by the Speed Booster, there really isn't much reason to use it with such a long lens. That said, My old Tamron 200-500 f/5.6 can effectively operate as a 500mm f/4 lens...which is just crazy. With a touch of 1.1x digital zoom, the vignette goes away but I'd rather have the 750mm cropped focal length.
Last night I was invited by a friend to go on the Old Strathcona Ghost Walk in historical Old Strathcona, Edmonton. It runs nightly this time of year with Halloween right around the corner. I decided this would be a great oppotunity to see what f/1.0 would be like with my NEX-7 and the Summicron.
Much of the walk is in the back alleys and residential areas so I knew the combo would be put to the test.
While some photos required a crazy dose of ISO, many got by with a reasonable amount. I was even able to snap some brackets for HDR processing hand held.
Check out the Edmonton Ghost Tours at http://edmontonghosttours.com/
Metabones Speed Boosters can be bought directly from Metabones: http://www.metabones.com/buy-speed-booster