Sony A850 vs Sony RX100 III: A Deep Dive into Two Distinct Camera Worlds

Choosing between the Sony Alpha DSLR-A850 (hereafter Sony A850) and the Sony Cyber-shot DSC-RX100 III (Sony RX100 III) can feel like comparing apples and oranges. Yet, both hail from Sony’s line-up and offer impressive image-making potential, albeit for very different users and scenarios.

With over 15 years of hands-on experience testing cameras - ranging from full-frame DSLRs to premium compacts - I’m here to walk you through an expert, detailed comparison that leaves no stone unturned. We’ll cover everything from sensor technology to real-world shooting across multiple photography disciplines, helping you find the perfect match for your creative journey.

At a Glance: Breaking Down the Basics

Before diving into nuanced performance and features, let’s quickly lay out their core specs for easy reference.

Right off the bat, you’ll notice striking differences. The A850 spans a hearty mid-size DSLR form, designed for robust handling and use with an extensive lens ecosystem. The RX100 III is a compact powerhouse built for portability without sacrificing too much on image quality or features.

Sensor and Image Quality: Full-Frame vs 1-Inch Sensor Dynamics

Image quality is often the top priority when selecting a camera. Let’s unpack the sensor technologies and what they mean for your photos.

Sony A850: The Full-Frame Workhorse

The A850 features a 25-megapixel full-frame CMOS sensor measuring 35.9 x 24 mm. Compared to crop sensors, a full-frame sensor offers:

• Superior low-light capability. Larger sensor area means bigger individual photo sites - capturing more light and reducing noise, especially at elevated ISOs.
• Greater dynamic range. The A850 boasts a measured 12.2 EV dynamic range per DXOMark, enabling it to recover highlight and shadow details in challenging lighting.
• Higher color depth. With 23.8 bits of color depth, the camera delivers smooth gradations, vital for skin tones and subtle color shifts.

Sony RX100 III: Big Sensor in a Compact Body

The RX100 III packs a 1-inch back-illuminated (BSI) CMOS sensor with 20 megapixels. While smaller (13.2 x 8.8 mm), the BSI design improves light gathering despite the smaller size. Key attributes:

• Decent low-light ability for its size. Score of 495 ISO in low-light DXOMark ratings, significantly lower than the A850 but excellent for a compact.
• Dynamic range slightly better than some APS-C compacts. Measuring about 12.3 EV, it competes well given the sensor size.
• Color depth rated at 22.4 bits, quite respectable for a compact.

Our take: If you’re after maximum quality, especially for large prints or professional work demanding low noise at high ISO, A850’s full-frame sensor stands tall. The RX100 III is a marvel for its sensor class but naturally can’t beat a bigger chip’s clean responsiveness.

Autofocus and Shooting Speed: Keeping up with the Moment

Autofocus (AF) and frame rates can decide the success of fast-moving or unpredictable scenes like wildlife, sports, or street photography.

Sony A850: Solid, Classic AF

• Uses 9 phase-detection AF points with multi-area modes.
• No face or eye detection capabilities.
• Continuous shooting maximum of 3 fps.
• Does not include live view AF or contrast detection.

These features were competitive in 2010 but lag behind modern standards, especially for tracking moving subjects.

Sony RX100 III: Compact with Advanced AF

• 25 autofocus points using contrast-detection, enhanced with face detection.
• Can track moving subjects with AF tracking enabled.
• Continuous shooting up to 10 fps, excellent for capturing fleeting moments.
• Supports live view AF and quick manual focus control.

The RX100 III’s AF system is lively and responsive, providing snappy focus in both stills and videos.

Our take: For fast action scenarios like sports or dynamic street photography, the RX100 III’s autofocus and speed deliver a noticeable edge. The A850’s AF is solid for portraits and landscapes but less suited to high-speed shooting.

Build, Ergonomics, and User Interface: Handling and Controls

You’ll interact with your camera daily, so ergonomics and ease-of-use critically affect your shooting experience.

Sony A850: DSLR Ergonomics

• Weight: 895 g, dimensions 156 x 117 x 82 mm - substantial but manageable for long-term handheld use.
• Robust weather sealing provides confidence when shooting outdoors in varied conditions.
• Traditional DSLR layout with a top-panel LCD, multiple physical dials, and buttons for quick access.
• Fixed 3” LCD with 922K dot resolution.
• Optical pentaprism viewfinder at 98% coverage and 0.74x magnification.

Sony RX100 III: Compact Convenience

• Weighs 290 g; pocketable dimensions 102 x 58 x 41 mm.
• No weather sealing, better suited for fair-weather use.
• Tilting 3” LCD with 1229K dots supports flexible shooting angles.
• Pop-up electronic viewfinder with 1440K dots and 100% coverage.
• Minimal physical controls reflecting compact size, but well laid out for intuitive use.
• Touchscreen not available but offers comfortable handling for a point-and-shoot.

Our take: The A850’s heft and controls provide serious grip and tactile feedback, ideal for professionals or enthusiasts who prioritize handling. The RX100 III excels in portability without feeling cramped, perfect for travel and street shooters valuing discretion and mobility.

Lens Ecosystem and Compatibility: Freedom vs Convenience

Lenses shape your creative potential. Understanding each camera’s lens options is vital.

Sony A850:

• Uses Sony/Minolta Alpha mounts compatible with over 140 lenses.
• Supports manual and autofocus lenses, primes and zooms across focal lengths.
• Enables professional optics including macro, telephoto, tilt-shift, and specialty lenses.
• Ideal for photographers wanting to build or maintain a versatile lens collection.

Sony RX100 III:

• Fixed 24-70mm equivalent zoom (F1.8-2.8) lens with excellent sharpness, close focusing (5 cm macro), and fast aperture.
• No lens change capability.
• Small and fast zoom covers common focal ranges for travel and everyday use.

Our take: The A850 wins hands-down on flexibility. If lens variety, optical quality, and tailored glass are priorities, the DSLR is unmatched. RX100 III’s fixed zoom is a solid performer but limits creative control over optics.

Battery Life and Storage Options: Stability for Long Shoots

Extended shooting demands reliable batteries and ample storage.

The A850’s battery life is superior, giving you the stamina for demanding sessions like weddings or events. The RX100 III’s shorter run is typical of compacts but supplemented by built-in Wi-Fi and NFC for quick sharing.

Versatility Across Photography Genres

Portrait Photography

• Sony A850: Larger sensor yields beautiful skin tones and creamy bokeh with quality primes. But slower autofocus and no eye detection means you must rely on manual focus precision.
• Sony RX100 III: Sharp 24-70mm lens and face detection aid easy portraits. However, smaller sensor limits shallow depth-of-field effects.

Landscape Photography

• Sony A850: Brilliant dynamic range and full-frame resolution are ideal for landscapes, enhanced by weather sealing for rugged outdoor conditions.
• Sony RX100 III: Good dynamic range but limited sensor size and lack of environmental protection reduce flexibility outdoors.

Wildlife and Sports Photography

• Sony A850: Limited 3 fps burst and basic AF make fast subjects challenging.
• Sony RX100 III: 10 fps and face/subject tracking better suit action, but short telephoto zoom limits wildlife reach.

Street Photography

• Sony A850: Bulky and conspicuous, less ideal for candid moments.
• Sony RX100 III: Compactness, silent shutter option, and fast zoom excel in street contexts.

Macro Photography

• Sony A850: Dependent on lens choice, can deliver excellent macro shots with dedicated glass.
• Sony RX100 III: Close focusing at 5 cm and sharp optics offer casual macro capability without extra gear.

Night and Astro Photography

• Sony A850: Superior ISO performance and longer exposure capabilities make it more usable in low light and astrophotography.
• Sony RX100 III: Usable up to ISO 12800 but noise becomes evident; lower light performance limited.

Video Capabilities

• Sony A850: No video recording function - strictly stills.
• Sony RX100 III: Full HD 1080p video at multiple frame rates, optical image stabilization, and time-lapse support via app make it a strong all-round multimedia tool.

Travel Photography

• Sony A850: Heavy and bulky, better for planned shoots rather than on-the-go travel.
• Sony RX100 III: Lightweight, pocketable, versatile zoom, and wireless sharing make it travel-friendly.

Professional Workflows

• Sony A850: RAW support, robust build, and compatibility with professional lenses and accessories enable demanding workflows.
• Sony RX100 III: Offers RAW files and decent editing flexibility but less suited for rigorous professional use.

Sony A850 front Sony A850 screen back Sony RX100 III front Sony RX100 III screen back

Price-to-Performance and Value Analysis

• The A850 is discontinued, mostly available used at varying prices, offering excellent imaging for a bargain if you find a well-maintained unit.
• The RX100 III retails around $748, delivering excellent value as a premium compact with video and wireless features.
• Both cameras balance features against price differently: the A850 targets quality-first photographers with lens investment, while the RX100 III appeals to convenience-focused creatives.

Final Thoughts: Who Should Choose What?

Choose the Sony A850 if:

• You want professional-grade still image quality on a full-frame sensor.
• You already own or want access to a wide range of compatible lenses.
• Your work involves landscapes, studio, portrait, or event photography requiring superior image fidelity.
• You prefer optical viewfinders, robust build, and longer battery life.
• You don’t need video and can cope with modest autofocus and burst rates.

Choose the Sony RX100 III if:

• You need a highly portable, everyday carry camera with excellent image quality for its size.
• You want fast autofocus, continuous shooting, and full HD video in a pocketable format.
• You prioritize convenience, wireless sharing, and versatile zoom lens without swapping glass.
• Your photography spans street, travel, casual macro, and video content creation.
• You are an enthusiast or advanced amateur who values compactness and smart features over ultimate image quality.

Getting Started and Next Steps

Photography is deeply personal. Whether you pick the DSLR classic A850 or the powerful compact RX100 III, it’s all about enabling your creative vision. I recommend:

• Trying each camera hands-on if possible to feel the ergonomics and interface.
• Matching your lens and accessory wishlist to the camera’s ecosystem.
• Considering workflow needs - storage, battery, and editing.
• Planning your typical shooting scenarios and weighing the importance of speed, size, and video.

Both cameras embody Sony’s innovation and can take your photography to meaningful places. Embrace the journey, explore their capabilities, and create images that inspire.

I hope this detailed comparison sheds light on these two venerable Sony models from very different eras and categories. Happy shooting - and don’t forget to share your best shots!

If you want personalized advice or lens recommendations, feel free to ask!