Autofocus

The PEN-F is geared toward enthusiasts seeking a capable, yet stylish rangefinder-style body. Keeping in mind this user base, the autofocus system in the PEN-F, specifically when used in Single Shot AF, is both fast and accurate. In the majority of shooting scenarios, even in low light, we found the PEN to offer AF precision and speed on par with the impressive performance of the Olympus OM-D E-M5 II.

That said, like most Micro Four Thirds cameras (including the E-M5 II), the PEN-F uses a contrast-detect AF system (CDAF) as opposed to the hybrid Contrast/Phase Detect AF system found in the flagship OM-D E-M1. The system in the PEN-F is comprised of 81 points, spread across a generous portion of the frame. Contrast-detect AF systems are very accurate, but can struggle when it comes to using continuous AF, especially while firing a burst of images.

AF point selection

Users can select any one the 81 AF points, or all of them, but not groups. To move a point when composing with the LCD, hit the left button on the four-way controller. Doing so will bring up a grid displaying all of the points, then use the four-way controller to move the point around. When your eye is to the finder, simply put your thumb on the touchscreen and move it around to select any one of the 81 points rapidly (this works even if you have touch-to-focus turned off). 

Interestingly, if you turn the PEN-F's touch-to-focus feature on (by tapping the screen), you suddenly have the ability to adjust the size of your focus point (which you can not do normally). Four different sizes are available and can be adjusted via a slider that appears on the right of the screen. Touch-to-focus is not the same as using the touchscreen to pick an AF point with your eye is to the finder. When using touch-to-focus, not only do you have more control over your point size, but more precision in moving your point around. The PEN-F also offers touch-to-shoot, which fires a frame once focus is locked.

Continuous AF

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We tested out the depth-tracking capabilities of the PEN-F using both an Olympus 40-150mm F2.8 Pro lens, as well as the Panasonic Leica DG 100-400mm f/4-6.3. Overall, we had similar results. In both cases, we had the cyclist ride toward the camera at a steady pace in and out of some shadows. The camera was set to center point C-AF for this demonstration (as opposed to C-AF+TR) with a burst of 5 fps, which is the fastest speed in which Continuous AF functions. We also had the camera set to prioritize focus over release - which we suggest all users do (CDAF with release priority is a recipe for out of focus shots).

It's worth noting that the selected AF point only lights up green once after focus is initially acquired; subsequently, only a green dot indicator at the upper right of the screen indicates whether or not focus is locked. This is particularly problematic because the AF point itself is very low contrast and difficult to see - making it difficult to keep over a moving subject. We often found we literally couldn't see the AF point. This can be somewhat remedied by engaging Touch AF, which keeps a lit green point on-screen (you'll still have to pay attention to the top right green dot for focus confirmation, though).

Overall, we were impressed with the F's hit rate when it came to simple depth tracking with a single AF point. The vast majority of frames are either in focus, or very close. We had similar results when we tested the Panasonic GX8 side-by-side with the PEN-F (we tried the Panasonic with both lens combos as well). We found the F performed best when we used AF-C with only a single AF point selected and tracking turned off. It's worth mentioning though, that the initial acquisition on a subject is crucial, and while the PEN-F does acquire focus reasonable fast, it can sometimes struggle with that initial acquisition, resulting in an entire burst of out-of-focus images.

However, while the two cameras both performed well at 5 fps, we were able to push the GX8 to 6 fps with continuous AF, while still maintaining a decent hit rate. And while the PEN-F can technically shoot bursts as fast as 10 fps with a mechanical shutter and 20 fps with and electronic shutter - the fastest it can shoot while using AF is 5 fps. Oddly, the AF offers both a 5 fps "High" mode and a 5 fps "Low" mode. This is confusing, especially because continuous AF will not work in the 5 fps High mode, only in the Low mode.

Continuous AF + subject tracking

Of the 45 frames in this burst, less than 10% are in focus: to be fair, this is not surprising. Cameras that employ only contrast-detect AF systems can be good at tracking a subject around the frame (subject tracking) before a shot is taken, but aren't necessarily good at actually focusing on the subject quickly. Furthermore, we've commonly noted subject tracking ability to plummet during bursts on mirrorless cameras, and the PEN-F is no exception. (Open in a new window and set the quality to 4K for best viewing).

Next, we complicated the parameters of our demonstration by having the cyclist weave at a steady pace toward the camera, switching the camera from C-AF to C-AF+TR to enable subject tracking. In our previous AF-C demonstration above, the PEN-F only needed to track the subject moving along a single axis, toward the camera. But in this demonstration, the camera must identify the subject and stay with it, as they not only move toward the camera but also left and right across the frame. As was the case with our AF-C demo, we had the camera set to 5 fps, with a priority on focus.

For each run, we'd tap on our cyclist to initiate AF on him. Simply put, the PEN-F is fairly good at identifying and sticking to a subject moving around the frame (something many mirrorless cameras do well), but falters as soon as you start firing a burst. This is not surprising: it is extremely difficult for the AF algorithm to identify and track a subject off the image sensor as that same very sensor is constantly being read and reset - five times a second in this case - to capture multiple images. Furthermore, contrast-detect AF systems already struggle to depth-track, quickly hunting the lens back and forth to determine when maximal contrast is achieved; complicating matters by also demanding the camera analyze multiple portions of the frame to follow your subject while hunting back and forth to aid the CDAF algorithm is probably just asking for too much.

Suggested settings for shooting bursts

In general, we found keeping the camera on the basic C-AF mode, with a single point selected and a frame rate of 5 fps or slower, to offer the best results when photographing a moving subject. Of course shooting this way requires you to keep your AF point over the subject for the entirety of the burst, which can be challenging.