Sony A6400 vs Sony RX100 VI: Which Sony Mirrorless or Compact is Right for You?

Sony’s Alpha a6400 and the Cyber-shot RX100 VI both occupy intriguing, albeit distinct, niches within their brand’s extensive lineup, appealing to advanced hobbyists and pro-level shooters. Despite sharing many core strengths, these two cameras deliver very different experiences optimized for separate photographic priorities. As someone who has put thousands of cameras through rigorous field tests, I’m excited to dive into a detailed, no-nonsense comparison between these two models, helping you decide which one fits your style, budget, and shooting ambitions.

Understanding the Cameras’ DNA

Before we get elbows-deep in specs and sample images, it’s important to frame the cameras in context.

• Sony A6400: Released in early 2019, this advanced APS-C mirrorless camera is designed for serious enthusiasts and professionals who want a versatile body capable of handling everything from portraits to wildlife. Its interchangeable lens design leverages Sony’s full E-mount lens ecosystem, arguably one of the most extensive and high-quality lens systems available outside traditional DSLRs.

• Sony RX100 VI: Launched just a few months earlier, this is a premium large-sensor compact - a remarkable pocket camera sporting a fixed 24-200mm zoom lens. It targets travelers and street photographers craving high image quality without the bulk of interchangeable lenses, and who value top-tier autofocus and video features packed into a tiny chassis.

Both cameras run Sony’s reliable Bionz X image processor, enabling similar 4K video capabilities and some shared technologies - but they are clearly engineered for different use cases. Let’s see how these design philosophies translate into real-world performance.

Ergonomics and Handling: Size Isn’t Everything, But It Matters

Handling is often overlooked in spec sheets but can make or break your shooting experience. The A6400 sports a rangefinder-style mirrorless body measuring 120x67x50 mm and weighing 403 g, while the RX100 VI is more compact at 102x58x43 mm and 301 g.

The A6400 is unmistakably a proper camera: it has a pronounced grip, direct access dials for exposure compensation, modes, and custom buttons that allow quick manual adjustments - think spinning a dial to tweak ISO or shutter speed without digging through menus. This tactile friendliness is a hallmark of pro-style mirrorless and makes working in the fast-paced world of sports or wildlife quite fluid.

On the other hand, the RX100 VI’s smaller body emphasizes portability and convenience. The controls are more compressed, with fewer physical buttons and smaller dials. While it does offer touchscreen control and a decent electronic viewfinder, its grip is minimal. This makes it ultra-discreet for street photography but less comfortable over long shooting periods or in rougher conditions.

If you’re traveling light or shooting casual events, the RX100 VI’s pocketability is a huge win. But for longer sessions or more demanding work, the A6400’s ergonomics truly shine.

Sensor and Image Quality: APS-C Muscle vs. 1" Sophistication

Size matters when it comes to sensors, and while the RX100 VI boasts a respectable 1-inch BSI-CMOS sensor (13.2x8.8 mm, approx. 116 mm²), the A6400’s APS-C sensor is significantly larger (23.5x15.6 mm, approx. 367 mm²), delivering approximately 3.2 times more surface area for light gathering. This fundamental gap underpins most differences in image quality, noise handling, dynamic range, and depth of field control.

Both cameras feature anti-aliasing filters to suppress moiré, with the A6400 offering a larger 24MP resolution (6000x4000 pixels) compared to the RX100 VI’s 20MP (5472x3648 pixels). The A6400’s larger photodiodes typically yield cleaner high-ISO performance and richer tonal gradations.

Using industry-standard DXOmark scores as one data point, the A6400 scores an overall 83 with a color depth of 24.0 bits, 13.6 EV of dynamic range, and low-light ISO rating around 1431 ISO at acceptable noise levels. While the RX100 VI isn’t officially tested on DXOmark, real-world testing confirms it performs well for a 1” sensor but can’t quite match the APS-C’s noise control or highlight recovery.

For landscape and studio photographers who demand the cleanest RAW files or large print sizes, the A6400 is the superior tool. The RX100 VI excels when portability is prioritized over absolute image tactical superiority.

Autofocus Systems and Speed: Tracking Life’s Moments

Sony is renowned for its autofocus innovations, and both cameras bring sophisticated hybrid AF systems combining phase and contrast detection points with face and eye tracking.

The A6400 sports 425 phase-detection points, covering a wide portion of the frame, with full eye autofocus for humans and animals, enabling sharp portraits even with shallow depth of field. This is complemented by impressive continuous AF tracking, firing off 11 frames per second with AF locked.

The RX100 VI offers 315 focus points, also with phase and contrast-detect AF, though it lacks the animal eye autofocus feature. Its standout is an exceptional continuous shooting speed of 24 fps, which is remarkable for a compact camera but comes at a slightly reduced buffer depth and fewer physical control options to manage rapid shooting.

For wildlife or sports photographers relying on pinpoint autofocus and tracking fast-moving subjects, the A6400's AF precision, customizable focus area selection, and animal eye AF deliver more confidence in challenging scenarios.

Portrait and travel shooters will appreciate the RX100 VI’s speed and decent AF performance, but it slightly trails behind on nuanced subject tracking.

Build Quality and Weather Resistance: Ready for Adventure?

For professionals working in varied environments, weather sealing is a non-negotiable feature.

The Sony A6400 features environmental sealing, meaning it can withstand some dust and moisture exposure - a big plus for outdoor, landscape, or wildlife photography in less-than-ideal conditions. It is definitely not a fully ruggedized body, but the sealing offers peace of mind for tough shoots.

In contrast, the RX100 VI lacks any environmental sealing. Its compact, tightly integrated design prioritizes slimness over durability, so use it cautiously in rain or dusty environments.

If your photography routinely takes you outdoors or in unpredictable weather, the A6400 is unquestionably better suited.

LCD and Viewfinder: Framing and Reviewing Your Shots

Both cameras feature 3-inch tilting, touchscreen LCDs, but with differences in resolution and articulation. The RX100 VI’s screen offers 1229k dots, slightly higher resolution than the A6400’s 922k dots, providing a crisp and bright display for composing and reviewing images.

The RX100 VI’s screen flips upward almost 180 degrees, ideal for vlogging or selfie shots, whereas the A6400’s tilting screen flips up about 180 degrees but cannot rotate fully forward for selfies (though it flips towards the top).

Viewfinder-wise, both use electronic viewfinders (EVF) with identical 2.36M-dot resolution, but the A6400 provides higher magnification at 0.7x versus the RX100 VI’s 0.59x. The A6400’s larger body physically accommodates a slightly bigger eyepiece, making the viewfinder experience more immersive and comfortable for extended shoots.

Lens Ecosystem: Interchangeable Freedom vs. Fixed Convenience

An undeniable advantage of the A6400 lies in Sony’s E-mount system, offering over 120 lenses ranging from affordable primes to fast telephotos and professional zooms. This endless customization allows photographers to adapt to virtually any genre or technique:

• Portraits: Fast 85mm f/1.8 or f/1.4 primes for exquisite skin tones and creamy bokeh
• Wildlife/Sports: Long 100-400mm zooms or super-telephoto primes for reach and speed
• Macro: Dedicated close-up lenses with excellent sharpness and stabilization

The RX100 VI is built around a single, albeit versatile, fixed 24-200mm F2.8-4.5 zoom lens. While this lens impressively covers wide-angle to medium telephoto needs, it cannot be swapped or upgraded. It’s nice for general travel photography but limits creative flexibility for specialized genres such as macro or shallow depth of field portraiture.

If lens choice matters - and for many enthusiasts it should - the A6400’s system is a major, long-term asset.

Burst Rates, Buffer and Memory: Capturing Action

Speed is critical in capturing dynamic moments. The RX100 VI can shoot bursts at an eye-watering 24 fps, far exceeding the A6400’s solid 11 fps. This gives the RX100 VI an edge in capturing fleeting street moments or wildlife action bursts.

However, buffering is important too. The A6400 supports larger buffer depths before slowing down, beneficial for sports shooters needing to capture longer burst sequences. Additionally, extensive customization of burst modes and AF tracking modes on the A6400 provides better control.

Both cameras use SD cards, compatible with UHS-I standards, though neither supports UHS-II, which mildly limits write speed for high-bitrate video or RAW burst shooting.

Video Capabilities: 4K with a Twist

Both the A6400 and RX100 VI deliver 4K UHD video at 30p, utilizing full pixel readout oversampling with minimal pixel binning, resulting in sharp, detailed footage.

The A6400 supports microphone input (3.5mm), a boon for serious video shooters seeking external mics, but lacks headphone out, making audio monitoring slightly more awkward. The RX100 VI has no microphone or headphone ports, limiting serious video production.

Image stabilization differs as well. The RX100 VI boasts optical image stabilization within the lens, critical for smooth handheld video. The A6400, however, does not have in-body image stabilization (IBIS), instead relying on optically stabilized lenses for shake reduction.

If video is a priority, the RX100 VI’s built-in stabilization and compact form factor are appealing for casual shooting, while the A6400, with its bigger sensor and microphone input, fits better in hybrid photo-video professional workflows.

Battery Life and Storage: Keeping You Shooting Longer

One of the RX100 VI’s compromises for its diminutive size is battery life: an official rating of about 240 shots per charge. This means carrying spare batteries or a power bank is advisable for day trips or video work.

The A6400 is stronger here, rated for roughly 410 shots per charge, facilitated by its larger, more robust NP-FW50 battery. It’s better suited to long days or travel photography, especially when combined with dual charging options via USB.

Each camera supports a single SD card slot, compatible with SDHC and SDXC cards (UHS-I). The A6400 also supports Sony’s proprietary Memory Stick Duo standard, although SD remains the preferred choice for capacity and speed today.

Practical Imaging Results: What’s in Your Frame?

I conducted side-by-side shooting of portraits, landscapes, street scenes, and wildlife, always ensuring consistent lighting and conditions.

Sony A6400 front Sony A6400 screen back Sony RX100 VI front

• Portraits: The A6400’s larger sensor depth and excellent eye autofocus produced consistently sharp eyes and smooth bokeh transitions in backgrounds. Skin tones felt natural and nuanced. The RX100 VI’s smaller sensor had slightly less background blur ability, and while sharp, the images felt more ‘compact sensor-like’ - good but less creamy.

• Landscapes: The A6400’s superior dynamic range preserved highlights and shadow details well, particularly with RAW files. The RX100 VI performed admirably but showed slightly more highlight clipping on bright skies and less latitude in shadows.

• Wildlife and Sports: The A6400’s autofocus system and lens flexibility were decisive. Images were tack sharp across varying distances, and burst shooting combined with focused tracking worked superbly. RX100 VI could capture fast-moving street action but struggled when subjects reached the edges of the zoom range or rapid focus adjustments were needed.

• Street Photography: The RX100 VI’s stealth factor and fast autofocus make it incredibly effective. It is so small, it practically disappears in hand, allowing candid shots without drawing attention. The A6400 is considerably bulkier but still wieldable on urban walkabouts.

• Macro and Night Photography: The A6400’s ability to adopt dedicated macro lenses and deliver low noise images at high ISO brings versatility that the RX100 VI’s lens cannot match. For astrophotography, the A6400’s reduced noise and longer exposure capabilities fare better.

Performance Benchmarks and Overall Scores

While Sony doesn’t release official benchmark numbers, DXOmark ranks the A6400 highly among APS-C cameras. The RX100 VI has yet to be officially tested but performs within expected limits for 1” sensors.

Combined with real-world usability, the A6400 leads in image quality, autofocus sophistication, and ruggedness, while RX100 VI scores on speed and portability.

How Each Camera Performs Across Photography Genres

For a clearer picture tailored to specific genres:

Final Recommendations: Which Sony Camera Should You Buy?

Choose the Sony A6400 if:

• You want maximum image quality, dynamic range, and low-light capability
• Interchangeable lenses, including macro, telephoto, and primes, are essential
• You prioritize professional autofocus features like animal eye AF and robust face tracking
• Shooting outdoor adventures with some weather sealing is a requirement
• You want a camera adaptable to multiple genres, including video with external audio options
• Battery life and comprehensive physical controls matter

Choose the Sony RX100 VI if:

• You need a truly pocketable, travel-friendly camera without sacrificing too much image quality
• You prefer a fixed zoom lens that can go from wide to telephoto quickly, ideal for street and travel photography
• Burst speed and autofocus responsiveness in a compact are priorities
• You want 4K video with optical stabilization in a tiny package
• You prefer simplicity and convenience over interchangeable lenses and extensive customization
• You don’t require weather sealing or professional audio inputs

Closing Thoughts: Not Just Two Cameras, But Two Lifestyles

Both the Sony A6400 and RX100 VI are excellent cameras within their spheres, and neither disappoints. Their strengths lie in their differences: the A6400 as a powerful, adaptable mirrorless for serious enthusiasts and professionals, the RX100 VI as a pocket rocket blending quality and portability.

Choosing between them comes down to assessing how much you value image quality, lens flexibility, and handling versus size, speed, and convenience. As camera testers with extensive backgrounds, we see these two complement each other rather than cannibalize. One opens doors to creative expansion; the other shrinks your kit without a huge compromise.

Whichever you pick, both carry Sony’s tradition of stellar autofocus, crisp imaging, and user-friendly interfaces worthy of embedding in your photographic arsenal.

Happy shooting!

Disclosure: All testing was conducted using stock camera firmware, consistent lighting conditions, and standard settings to ensure fair comparisons. Images displayed were shot RAW and converted with identical processing parameters.