Autofocus Performance

Historically, third party lenses haven't always been compliant enough with the lens-mount standard to able to make use of every bit of tech that own-brand lenses can, especially in terms of autofocus. The original Sigma DN lineup of F2.8 primes for mirrorless spring to mind in this respect. They were only able to use the very center of the Sony a6000's phase-detect AF coverage area, resorting to contrast-detect AF outside this region.

Thankfully, with the 30mm F1.4 DN and the a6000 series, this is no longer the case. The lens is able to make use of all of the a6300's PDAF coverage area, although it will quickly jump back to CDAF when focus is placed outside the PDAF area.

Being able to use the entire PDAF coverage area means placing focus off-center with very shallow depth-of-field won't produce out of focus shots easily. Photo by Samuel Spencer

Unlike the previous DN lenses, it behaves exactly as a native E-mount lens does. Unfortunately, this means the camera forcing it to stop down to focus. Therefore, at F8 and below, the camera doesn't get enough light to use PDAF and will instead drop back to CDAF, with all the trial-and-error wobble this entails.

Even though the Sigma allows the Sony to flex all of its PDAF muscles, it isn't as quick to focus as the 35mm F1.8 OSS. It's by no means a slouch, but the Sony is much more snappy, feeling near-instantaneous in terms of drive speed, where the Sigma just barely lags behind.

Video Performance

What the newfound compatibility also means is when used with the a6300 the Sigma can focus continuously in video, making it a handy bright lens for videographers that want shallow depth of field but can't afford a focus puller, and need to depend on a camera's AF system when shooting video. 

In terms of manual focus, both lenses operate using a focus-by-wire system, but exhibit different behaviors. The Sigma isn't a linear response, and instead will move its element based on the speed the barrel is turned, making a quick rack from infinity to minimum focus distance doable with a quick flick of the wrist, although trying to do it smoothly (as it would be in video) slows down the drive speed quite drastically to about the same speed as the Sony.

The Sony is programmed to behave in a linear fashion, and takes quite a few motions of the wrist to move from MFD to infinity. This means videographers using manual focus will be able to better predict positions of the focus ring when planning shots, although the slow action doesn't make it an ideal choice either. Thankfully, both drive their focus elements smoothly without any sort of jumpy behavior that can be seen with some focus-by-wire primes, and also both report focus distance next to the distance scale on the camera's screen.

There are a couple other things videographers might consider. The Sony's OSS and minimum aperture of F22 are both handy features. The OSS can help remove some shake when shooting handheld, and being able to stop down to F22 gives videographers a better chance to reach the 1/framerate video 'rule' that helps make video look smooth.

Conclusion

It's not as tight as a full-frame 50's field of view, but not as wide as a 35's, which ends up being an easily usable balance between the two. Photo by Samuel Spencer

With the 30mm F1.4 DC DN Contemporary, Sigma has produced a real winner. They've made a sharper and brighter autofocus lens than anything available in the APS-C E-mount lineup. Not only that, but they've also eliminated any major penalties there used to be with using a third-party lens on E-mount cameras.

All this has been achieved while costing less than the 35 F1.8 OSS, and in fact many APS-C F1.4 primes for other systems. There is a slight cost in terms of distortion, but the high amount of sharpness means images should be more tolerant of correction.

The result is a lens that deserves no less than the highest praise. It is a relatively lightweight F1.4 prime for low light needs and producing shallow depth of field, and makes an excellent lens for street shooting, or anywhere else a photographer might typically use a 50mm lens (or in this case 50mm equiv.). A beginner wanting to replace or augment their kit zoom with a decent walk-around prime should definitely consider the Sigma 30mm F1.4 DC DN | C and learn how to 'zoom with your feet.' Seasoned photographers will love the amount of quality packed in to its size, and will find the 45mm equiv. field of view is as functional and versatile and creative as the classic 50mm field-of-view is. 

Sigma 30mm F1.4 DC DN | C (E/EF-M mounts)
Category: Normal Lens
Optical Quality
Build Quality
Autofocus
Ergonomics and Handling
Value
PoorExcellent
Conclusion
The Sigma 30mm F1.4 DC DN | C is one of the sharpest lenses available for Sony E-mount, and costs less than many of the prime lenses it outperforms. Combine that with being one of the brightest autofocus lenses available as well, and the result is an excellent lens for anyone interested, whether they're just getting started, or are a seasoned shooter.
Good for
A wide variety of shooting situations such as environmental portraits, low light, street shooting. Great as a standalone prime, or paired with a kit zoom.
Not so good for
High magnification/macro shooting, or shooters that prefer prime lenses with a wider field of view, or use in inclement weather.
87%
Overall score