Inside this issue
Novel Adapter for NEXViewfinder
One of the problems with using full frame lenses on a cropped sensors is that your focal length is 'increased' by the same amount so if you use a 'normal' 50mm lens on a 1.6x crop sensor it becomes a medium telephoto of about 80mm.
Not only that but the amount of light is also reduced so that the effective aperture becomes increased also. This means your f/1.8 normal lens has the same light gathering ability as an f/2.8 lens and also the same relative depth of field.
However, Metabones have created a focal length reducing adapter for the NEX that allows you to mount Canon EF mount lenses on Sony E mount. Only for Sony crop sensors though.
Effectively what is happening is it's bending the light from the limit of the image circle of the lens so that it properly covers a crop sensor rather than a full frame sensor. It's like an EF to EF-S converter!
Now Philip Bloom has been testing the adapter and seems to like it a lot (see Sony Alpha rumours website too) but obviously he's only testing it in terms of HD resolution which is less than half of the resolution of the camera as used for stills. It remains to be seen whether the optics in the adapter are good enough to be used whilst retaining the optical performance of the original lens.
What it does do is allow you to use tilt shift lenses on a Sony NEX camera at the original wide angle focal lengths! Very interesting!!
We'll try to get more information from the supplier about how good the performance is but Prof. Brian Caldwell who supplies the optical elements for the adapter has a very good reputation in lens design for scientific and archival purposes.
The lens is on pre-order at the moment and the price is a quite hefty £380 but it's a definite sign of what the NEX and it's short distance from sensor to lens mount allows custom manufacturers to do. Interesting times...
UPDATE: Here's a quote from Brian Caldwell
"We designed an entirely separate optical system for micro 4/3. However, the magnification is the same as the NEX version: 0.7x. In order to get a significantly smaller magnification while maintaining excellent image quality we would have had to get much closer to the image plane with our optics. Unfortunately, the m4/3 cameras don't allow this.
The good news is that the performance of our 0.7x optics for micro 4/3 is really good, and I expect that some pixel peepers will prefer it over the NEX version. If you look at the MTF curves in the white paper you can see that the m4/3 version gives higher performance in the corners than the NEX version. We could have saved a lot of money by re-using the NEX optical cell for the upcoming m4/3 Speed Booster, but we decided to maximize image quality instead."
Which m4/3 camera do I buy?