By site editor Dan Chung:
Newsshooter.com technical editor Matt Allard talks again with Bohus from Fotodiox about the company’s upcoming B4 ENG lens optical adapters. The adapters expand the small B4 image from an ENG lens using optics to cover larger sized sensors such as M4/3 or S35. Because the optics are expanding the image there is of course light loss, but Fotodiox are not giving a figure at the moment. The lens servo unit can be powered using a battery pack via a special cable which allows motorised zooming.
A number of competing solutions already exist. For M4/3 users it is possible to buy a purely mechanical B4 to M4/3 adapter, then use a B4 lens with a built-in range extender engaged to make the lens cover the sensor size. Power cables that power the zoom servo are available on Ebay and other places.
MTF services in the UK have been making an optical B4 to EOS adapter since 2012 that are also designed to be used with the range extender of an ENG lens. We previously tested one here.
What sets the Fotodiox solution apart is the lack of the need for a lens with a built-in range extender, and also the lower cost of the solution. How good the optics are remains to be seen. We are of course keen to see the results here on Newsshooter.com
Interestingly Fotodiox were also showing a version of the adapter on full-frame Sony A7. While they say this is a work in progress I very much doubt that it would be made to cover a full-frame image without too much image degradation and extreme loss of light. Time will tell.
A word of caution about lens choice with all these adapters. In my experience some of the older standard definition B4 lenses don’t work well when used this way. Distortions in the corners and chromatic aberrations can be very obvious. Try to test your B4 lens with the adapter first before buying to be sure you are comfortable with the results.
The very best solution I’ve seen is Sony’s B4 to FZ adapter for the F5 and F55 with used high end HD B4 lenses. This combination is optically excellent and Sony claim no resolution loss compared to using the B4 lenses on a real ENG camera – although you still lose several stops of light. Sadly this comes at a high price and the solution on works on the F3, F5 and F55 cameras.