How to trick Panasonic mirrorless cameras into thinking your APS-C lenses are full-frame

If you’re using Sigma EF mount lenses with the Sigma MC-21 on Panasonic’s full-frame mirrorless bodies, then your camera is likely going to be forced into APS-C or Super35 mode when attempting to shoot video. With some 3rd party lenses, you don’t get such a restriction and the camera will happily let you shoot full-frame – even if the projection circle doesn’t quite cover the sensor.

While it may seem like a strange thing to want to do, some APS-C lenses, like Sigma’s 18-35mm f/1.8 Art lens, will actually completely cover a full-frame sensor at certain focal lengths. In this video from Nate’s Film Tutorials, we learn how we can trick the Panasonic S1H into opening up that full-frame option.

As you can see in the video, using the Sigma 18-35mm f/1.8 Art lens with the Sigma MC-21 adapter on the Panasonic S1H limits you to Super35 shooting mode (a similar crop to the standard 1.5x APS-C). But when he attaches the Tokina 11-16mm f/2.8 lens, no such restriction applies and the camera will happily go into full-frame shooting mode.

The Sigma 18-35mm f/2.8 will actually cover an entire full-frame 35mm sensor when you hit a focal length of around 28mm or longer – essentially turning it into a 28-35mm f/1.8 lens on full-frame sensors. Being able to get that focal length with that fast f/1.8 aperture can be a very attractive proposition for many shooters.

I suspect it’s likely due to the fact that the MC-21 offers full communication between their own brand lenses and Panasonic cameras – after all, they’re all part of the same alliance, and Sigma knows everything about their own lenses and the protocols they support. But the Tokina 11-16mm may not necessarily send that same signal to tell the MC-21 “Hey, I’m an APS-C lens!” so the MC-21 doesn’t pass it along to the camera body.

Nate offers up two solutions in the video. One is to simply use a “dumb” adapter that doesn’t pass through any electronic communication at all. This would definitely solve the problem, although you completely lose any autofocus or aperture control – and image stabilisation, if the lens you’re using possesses it.

The other is to simply keep with your existing MC-21 setup and with the camera powered up, twist off the lens slightly to break the electronic connection. This then allows the camera to switch to full-frame mode. But what’s interesting is when you twist the lens back to lock it into place again, it doesn’t send that signal to the camera that it’s an APS-C lens, so you can stay in full-frame mode.

Now, turning off the camera resets the whole thing, and the MC-21 sends the “Hey, this is an APS-C lens!” signal to the camera when it initialises, so you’ll have to apply the workaround again each time you turn on your camera. But, if you wanted to utilise the extra field of view on your Sigma APS-C EF mount lenses on the Panasonic S1H, now you know how to do it.

What other APS-C lenses do you know of that will actually fill a full-frame sensor?

[via L-Rumors]