Wide Converters in Mark II Artist’s Viewfinder

Today we announced the beta of Mark II Artist’s Viewfinder. With the Mark II we took a new direction on how we handle wide converter lenses. In the past we just multiplied frame line positions with the wide conversion factor, not doing anything about the optical aberrations of the converter lenses. And believe me, they have many. Distortion, chromatic aberration, centering errors, you name it, the converter has it.

Most of these aberrations can be safely ignored as nobody takes real images with a viewfinder. One of them however, distortion to be exact, is a huge problem. It enlarges the center portion of the image and compresses the edges, making the effort of precise frame line positioning futile.

Given the immense power of today’s iPhone GPUs, we set out to get rid of wide converter distortion forever. And I’m pleased to tell you that we succeeded: the Mark II sports real-time distortion correction! Following is an example of its power.

Before and after distortion correction

Before and after distortion correction

ALPA’s ACAM Super Wide Converter exhibits about 11% barrel distortion (on the left). Which is completely eliminated in the Mark II (on the right). Yes, resolution suffers, but it is pretty much enough for viewfinder use. There’s also some darkening on the lower left corner (the converter vignettes heavily and asymmetrically on the iPhone 5s – which isn’t a big issue after the correction).

With the corrected view we can simulate super-wide lenses, which is a blessing for landscape and architecture photography. But I also regularly use the ALPA’s iPhone Holder together with the ACAM SWC as a viewfinder for my Canon TS-E 24 pano stitches. Here’s a screenshot I took on my old iPhone 4 while composing The Circle.


Composing a stitched pano

Note that the iPhone 4 isn’t fast enough to do the correction at full Retina resolution – all other supported iPhones (4S/5/5S) are.

At launch we’ll support ALPA’s ACAM SWC, but the lab and the measurement technology is ready, and we’ll add adapter/device combinations as we measure them. On the device front, iPhone 4/4S/5/5S are supported.

So if you regularly shoot wide, or want to get a tool that allows you to visualize tilt/shift stitches, then head to the Mark II’s site and sign up for a beta. Seating is limited, so hurry! Then it’s time to order an ACAM SWC from ALPA.