Pro II shares the same pull-back mechanism for autofocus and manual focus switching as many other lenses. Focusing is internal, so the length of the lens does not change, but the zoom ring is mechanical and the lens does extend as we zoom in to 40mm.

The rugged, metal build quality that's dust-, splash- and freeze-proof really makes this lens an option for professional photographers who've been wanting to move to a smaller, more portable camera system but were too underwhelmed by the lens selection and performance to do so. Overexpose by a stop and you’ll get these beautiful muted colors that are so popular with film photographers.It uses a MSC (Movie and Still Compatible) mechanism to silently and quickly drive the focusing lenses. If you have a function specific to the way you shoot like Magnify, Peaking or Digital Teleconverter, you can assign one of them to a button on the lens barrel and access it instantly. In fact, I'd probably go as far as to say that the 12-40 represents the very best one lens solution currently available for the system. When paired with a compatible camera, you’ll be able take shots with deep focus from foreground to background through creating a composite image by combining multiple shots with different focus. The result is a compact, lightweight focusing unit that enables 50fps sequential shooting while letting you shoot stills and movies with speed and accuracy.

If you’re shooting on a Panasonic body, the Panasonic lens probably gets the nod simply because it has OIS and the Olympus does not.

PRO II Lens is a superbly built lens which features Advanced IP53 dustproof and splashproof performance, and freezeproof performance to -10°C. With the E-M1 I have never had a problem whatsoever and I have managed to focus even in really dark conditions like a disco. The following example demonstrates how close you can get to your subject, in this case a Compact Flash memory card. The oddity is that the camera takes the modest amount of pin cushion distortion at marked 25mm focal length and changes it into a modest amount of barrel distortion!