The fast and reliable eye-AF means the a7C is very good at letting you grab spontaneous moments.

Key takeaways:

  • Autofocus is impressive and easy to use (once you've engaged its tracking mode)
  • Tracking works well, especially for human or animal subjects
  • Video is detailed but shows some rolling shutter or imposes a crop
  • 8-bit capture means it's not the best choice for committed videographers

Autofocus

The a7C has one of the best autofocus systems currently on the market, but in traditional Sony fashion, you need to change some settings to get to its best settings. Out of the box, the camera is in AF-A mode, which auto-selects between modes that conduct a single AF attempt and one that continuously attempts to refocus on moving objects. It also locks you out of any of the camera's tracking modes.

AF area modes

The a7C has seven AF area modes, for which of each there's also a variant which tracks your selected subject (if you're in AF-C mode). In most day-to-day use, you'll probably only use one or two of these modes.

Use the Fn menu to engage AF-C and you'll then be able to select one of the tracking variants of the AF area modes.

There are seven AF area modes, along with tracking versions of each of them. A menu option called 'Focus Area Limit' lets you hide any of the AF areas you don't use, to reduce the list to a more manageable number.

We tend to find the tracking version of Flexible Spot Medium works well for most photography, then we set up a custom mode that has either a non-tracking Flexible Spot Small point or Wide-area AF defined as its AF area mode: this lets us assign that custom mode to a button so we can temporarily switch to using a fine point to ensure we're focused on exactly the right detail, or to a mode where the camera picks a subject.

Once one of the tracking modes has been engaged, the camera will track the subject under the AF point, and will use its highly effective face and eye tracking if it detects a human subject. If the camera is tracking a person it knows to continue doing so, even if they look away, so you don't need to worry about uncontrolled refocusing just because the face being tracked is no longer visible.

Autofocus performance

Autofocus works very well, both in terms of delivering in-focus images and in terms of tracking the subject you've specified. With no further input from the user it can turn its hand to most things from family photos to sports, including the unpredictable movement of children.

The a7 III already did so well at this kind of tracking that there's little point re-testing the a7C, but here's a test of the eye-detection in low light.

Here you can see the camera begin to hit the limits of its AF capabilities. It is successfully following the subject's eyes but sometime failing to focus in the right place.

The good news is that the AF system works very similarly in video mode, but with settings to define how readily the camera should be willing to refocus to a different depth, and how quickly it should drive the AF motor when doing so. These let you ignore, or refocus on other subjects entering the scene, and let you slowly pull focus or rapidly maintain focus, depending on what you're trying to achieve.

Video

The a7C can shoot pretty decent 4K video, with 24p footage taken from the full width of the sensor and 30p taken from a slight crop. The camera provides headphone and mic sockets to help capture clean audio, along with zebra markings to help set and maintain exposure. There's also focus peaking, to help set and maintain focus, but the autofocus is usually dependable enough to rely on.

Autofocus works differently in video mode, with all the tracking AF area modes marked as unavailable. Instead, to track a subject you need to select 'Touch Tracking' (Camera tab 2| Custom Operation2 | Func. of Touch Oper...). With this selected, you can simply tap on a subject and the camera will track it. However, you'll need to change the setting back if you just want tapping to specify the AF position, when shooting stills.

The prominent red [REC] button on the top of the camera makes it easy to start video capture but perhaps too many of its stills settings are also applied in video mode.

Movie mode has a different set of Fn menu options, which you can customize, along with a different set of Fn button assignments for video. However most key settings, including exposure settings, white balance and color mode are carried across from stills to video capture. This can make it much slower to switch back and forth between the two ways of shooting, since you're likely to have to change a significant number of settings each time you swap. Most of the a7C's peers do a better job of letting you separate the two.

All footage is 8-bit, which limits grading flexibility, even if you shoot using one of the camera's Log modes (accessed via the 'Picture Profiles' setting). This means there are better choices for committed videographers who are color-grading their footage.

The a7C's 24 frame-per-second 4K footage is its most detailed, however, it also has the most rolling shutter, which means fast movement by the camera or subject can appear skewed or distorted when you play it back. This is less of a problem in 30p mode but this applies a 1.2x crop, meaning it's harder to achieve wide-angle shots (especially with the kit zoom, which already doesn't extend particularly wide). 1080p footage is rather soft and prone to aliasing.