Sigma fp vs Sony A9: A Deep Dive Into Two Remarkable Full-Frame Mirrorless Cameras

In the ever-evolving landscape of mirrorless cameras, two models from very different philosophies stand out: the minimalist yet audacious Sigma fp and the powerhouse Sony Alpha A9. Having spent countless hours behind the lens with both, I’m eager to share a deep, hands-on comparison that goes beyond spec sheets into how these cameras perform in the real world - from landscapes to wildlife, portraits to street photography, and everything in between.

If you’re debating between the Sigma fp and Sony A9, buckle up. This is not just a numbers game; it’s a journey through ergonomics, usability, optics, and the subtle art of image-making. Let’s begin with a quick peek to set the stage...

First Impressions: Physical Presence and Ergonomics

At first glance - or should I say first grip - these two cameras feel worlds apart. The Sigma fp is tiny, light, and minimalist, whereas the Sony A9 feels like a Swiss Army knife of dials and buttons, crafted for professional reliability and extensive control.

The Sigma fp weighs in at a mere 422 grams with dimensions 113 x 70 x 45 mm, embracing a slender rangefinder-style body. It’s like the “skinny jeans” of full-frame mirrorless; sleek and fuss-free. In contrast, the Sony A9, weighing 673 grams and measuring 127 x 96 x 63 mm, offers a beefier SLR-style body that’s ergonomically robust to handle pro workloads and larger lenses.

If your photography tends to involve long shoots or heavy glass, the A9’s heft actually feels reassuring. Sigma’s fp, on the other hand, is a joy for travel, street photography, or any situation demanding ultra-portability without sacrificing sensor size.

Design and Control Layout: Simple vs. Sophisticated

While size is one thing, control layout reflects philosophy and intended user experience. The Sigma fp is stripped down to essentials - a design no doubt inspired by filmmakers and modular shooters - but that minimalism can feel like a double-edged sword.

You’ll find no top LCD panel, no dedicated dials for ISO, shutter speed, or drive modes - just a handful of buttons and a touchscreen interface. This keeps it compact but requires more menu diving or reliance on external controllers for speed-critical adjustments.

The Sony A9 sports a more traditional pro camera layout. Dual memory card slots, a large electronic viewfinder (more on that later), a tilting LCD screen, and direct access dials make it ideal for fast-paced shooting environments like sports or wildlife where every millisecond counts.

Personally, I appreciate having physical controls at my fingertips when under pressure, but the Sigma fp’s design shines in studio or cinematic contexts where the camera is part of a rig or workflow rather than the sole shooting tool.

Sensor Technology and Image Quality: Two Full-Frame Giants

Both cameras leverage full-frame BSI-CMOS sensors, but their design intents diverge significantly. The Sigma fp's 24.6MP sensor offers a good balance of resolution and noise performance, optimized for image quality and video shooters alike.

Conversely, the Sony A9 has a slightly lower resolution 24MP sensor, but what it lacks in pixel count it makes up for with phenomenal speed and low-light capability.

The Sigma fp’s 25MP sensor yields crisp 6000x4000 pixel photos and impresses with excellent color depth and dynamic range, though it’s not yet benchmarked extensively on DxOMark. Rich skin tones and subtle gradations particularly stand out, making it a delight for portrait and fashion photographers.

Sony’s A9 sensor is battle-tested with an overall DxOMark score of 92, outstanding color depth at 24.9 EV, and dynamic range exceeding 13 stops at base ISO. Its low-light ISO performance is tremendous, reaching effective usable ISOs up to 51,200 without too much noise. This makes the A9 a top pick for event, sports, and astrophotography where light is challenging but action won’t wait.

Viewing Experience: EVF vs Having None at All

One of the most contentious points for many Sigma fp users (myself included) is the absence of any electronic viewfinder.

If you’re used to composing via an EVF or through an optical prism, the fp feels at first like a novelty - relying solely on a 3.2-inch fixed touchscreen at 2.1 million dots can be tricky, especially in bright environments.

Sony’s A9 sports a 3-inch tilting touchscreen at 1.44 million dots and a phenomenal 3.68M dot OLED electronic viewfinder with 0.78x magnification. This EVF delivers crisp, real-time previews, excellent color fidelity, and lag-free action tracking - essential for fast-paced shooting.

From my testing, the A9’s EVF becomes an indispensable part of my workflow for both manual and autofocus shooting, while the Sigma fp’s screen benefits from touch interface simplicity but sometimes requires an external EVF module for critical framing.

Autofocus Systems: Precision vs Speed

Where Sigma’s simplified approach is most evident is autofocus. The fp uses a contrast-detection autofocus system with 49 points and face detection, but lacks phase-detection or animal eye AF.

Sony’s A9, built for speed, packs a staggering 693 phase-detect autofocus points covering 93% of the frame and sophisticated tracking algorithms including real-time eye, face, and even animal eye detection.

For sports and wildlife shooters, this makes a night-and-day difference. I tested both on dynamic subjects: the A9 locked focus milliseconds faster and tracked errant movements with reliability that made me forget I was shooting.

Though the Sigma fp can do continuous AF and face detection, it lags behind in aggressive tracking and low-light AF. For portrait work, the fp’s AF is enough but expect some missed moments with fast action.

Burst Shooting and Buffer Capacity

An extension of autofocus speed is continuous shooting performance. Sony’s A9 boasts a blistering 20 frames per second with silent electronic shutter, ideal for sports, wildlife, or any fast-moving subjects.

Sigma fp offers a respectable 12 fps mechanical shutter rate but lacks the silent high-speed electronic shutter capabilities and boasts a smaller buffer.

In practical terms, if your shooting style often revolves around capturing fleeting action sequences or decisive moments, the A9 is the clear choice. On the other hand, the fp’s burst rate caters more to casual continuous shooting or video frame grabs.

Image Stabilization: Built-in vs Not

One area where the Sigma fp stands out as minimalist is its total lack of in-body image stabilization. Stabilization support is entirely lens-dependent.

Sony’s A9 incorporates a sophisticated 5-axis sensor-shift stabilization system. This makes a phenomenal difference when shooting telephoto or handheld video, allowing easier use of longer angles and smoother footage.

In my hands, the A9’s IBIS often saved shots that would otherwise have been blurred - especially under low shutter speeds or in dim lighting. The fp demands more of the photographer or the lens ecosystem on this front.

Lens Ecosystem and Mount Compatibility

Lens selection can make or break a camera system. Sigma fp uses the Leica L-mount, a newer but growing lens mount with a more modest native lens library of about 30 lenses, ranging from fast primes to zooms - plus the ability to use adapters for other lenses.

Sony’s E-mount, however, boasts an immense catalog (over 120 native lenses), with offerings covering every focal length, aperture range, and specialty lens you can imagine - including high-end G-master primes and professional sports glass.

If lens variety and future-proofing are priorities - and let’s face it, for many professionals they are - the Sony A9 has an undeniable advantage here.

Video Capabilities: Lightweight Versatility vs Pro-Grade Features

Sigma’s fp gets points for razor-sharp 4K UHD video at 30p with 8-bit 4:2:0 recording in MOV format, plus professional audio I/O options (mic and headphone jacks). Despite its petite frame, it supports time-lapse recording and has a modular design that integrates well into video rigs.

The Sony A9 records 4K UHD video as well, though it’s more geared toward stills photographers needing high-quality video without extensive filmmaking features like internal log profiles or 10-bit capture (reserved for Sony’s A7S/FX lines).

Critically, the Sigma fp’s minimalist but modular philosophy makes it a darling among cinephiles who prioritize lightweight setups and high image quality in video, whereas the Sony A9 aims more at hybrid shooters prioritizing autofocus and image stabilization in both video and stills.

Weather Sealing and Durability: Both Built for Endurance

Both cameras feature environmental sealing suitable for dust and moisture resistance but lack full waterproof or freezeproof ratings.

Sony’s A9, designed explicitly for professional outdoor use, feels more rugged with robust body construction. The Sigma fp’s rangefinder-style body is solid but feels more delicate; careful handling is advisable during demanding shoots.

For travel, events, or wilderness usage, the A9’s build inspires more confidence out of the box.

Battery Life and Storage

Sony’s A9 packs a large NP-FZ100 battery offering around 650 shots per charge under typical usage - an excellent score for a mirrorless camera with an EVF.

Sigma fp uses a smaller BP-51 battery, with shorter life (precise figures vary, but effectively under 300 shots per charge). The fp’s small battery is understandable given its size but means carrying spares for extended shoots.

Storage-wise, the A9 features dual SD cards, both UHS-II compatible, offering versatility and backup options critical for professionals. Sigma fp offers a single SD card slot with UHS-II support, adequate for casual shooters but somewhat limiting for workflow-intensive professionals.

Connectivity and Workflow Features

Sony’s A9 shines with integrated Wi-Fi, Bluetooth, and NFC for seamless tethering, remote control, and quick file transfers - vital for fast turnaround environments like sports photography or event coverage.

The Sigma fp, in contrast, lacks wireless connectivity altogether. For those wanting robust remote capture or on-the-go sharing, the Sony makes life easier.

Both cameras have USB and HDMI ports, and microphone/headphone jacks, but the A9 supports USB 2.0 speeds (a bit lagging behind current standards) while fp offers USB-C.

Price-to-Performance: Where Value Lies

Let’s talk numbers: the Sigma fp launched around $2,050, while the Sony A9 carries a heftier $4,498 price tag (at launch and still close today).

What you’re paying for with the A9 is an incredibly fast and reliable imaging machine with pro-level autofocus, buffer capacity, EVF clarity, weather sealing, lens selection, and wireless features.

The Sigma fp offers groundbreaking portability, superb video integration, and excellent image quality in a tiny package, making it ideal for creators who prioritize size and multi-functionality over blazing autofocus or burst speeds.

Putting It All Together: Who Should Pick Which?

To make this comparison easier to digest, I’ve broken down strengths per genre:

• Portrait Photography: Sigma fp’s color rendition and skin tones shine; A9’s eye AF and tracking give consistent focus on eyes and faces during dynamic sessions.
• Landscape Photography: Both excel in dynamic range but the A9’s weather sealing, battery life, and lens options edges the day.
• Wildlife Photography: Sony A9 dominates with autofocus speed and tracking; Sigma fp less reliable for fast critters.
• Sports Photography: A9’s 20fps and advanced AF make it unmatched; Sigma fp less suited for high-speed action.
• Street Photography: Sigma fp’s compact form factor and quiet shutter make it a joy; A9 is bulkier but delivers better AF in complex lighting scenes.
• Macro Photography: A9’s IBIS helps stabilize finely focused shots; both depend on lens, but A9 offers more compatible macro primes.
• Night/Astro Photography: A9’s higher ISO performance and low-noise sensor hold advantage.
• Video: Sigma fp’s modular design, clean 4K, and audio features appeal to filmmakers; A9 competent but less cinematic.
• Travel Photography: Sigma fp’s size and versatility win for minimalist travel; A9 suits photographers wanting a do-it-all pack.
• Professional Work: Sony A9’s robust build, dual card slots, wireless and EVF features better match professional demands.

Sample Images: Seeing Is Believing

Because words only go so far, I’ve included a gallery of sample images shot under diverse conditions with both cameras:

Sigma fp front Sigma fp screen back Sony A9 front Sony A9 screen back

Comparing side by side, you’ll note the A9 is sharper in fast-action and low light shots, while the Sigma fp dazzles with color and tone in portraits and video capture frames.

Real-World Testing Notes: What Did I Notice?

• The Sigma fp is incredibly liberating - a full-frame still/video hybrid you can tuck in a coat pocket. But it demands a more deliberate shooting style; no autofocus wizardry or rapid fire bursts.
• The Sony A9 feels like a beast bred for pro photojournalism, sports, or wildlife where latency and reliability govern success.
• Sigma’s lack of EVF and subdued controls can be frustrating outdoors or during fast shoots; you’ll want accessories.
• Battery life on the A9 is far superior; a single charge can last an entire wedding day.
• Sony’s Wi-Fi/BT makes quick client delivery easier; Sigma fp demands cable or card removal.
• Sigma’s exposure latitude is excellent, great for extensive color grading and video post work.
• Sony’s autofocus in challenging light or cluttered backgrounds is simply better at not losing focus.

Overall Performance Ratings

Here’s the straightforward summary of strengths and weaknesses in a quick-glance rating panel, reflecting my testing impressions:

Final Thoughts: Two Cameras, Two Worlds

There’s no doubt these two cameras serve distinct overlapped niches with some crossover.

If you crave a pocketable full-frame powerhouse with gorgeous color, brilliant video chops, and surgical minimalism geared toward mindfulness in image making, Sigma fp is your spirited companion - it demands more of you, but rewards with creative freedom rarely found at this price and size.

If, however, your craft demands speed, resilience, tracking precision, and a deeply integrated pro workflow in a mirrorless body with a thriving lens ecosystem, the Sony A9 remains a benchmark - even two years post-launch - deserving your serious consideration despite the steeper investment.

Whichever side of this mirrorless divide you choose, you’re investing in cameras that represent meaningful technological achievements. No gimmicks, just tools with their own philosophies, powers, and quirks.

Happy shooting!

Feel free to share your experiences with either camera or drop questions below - I’d love to hear how they fit into your camera bag and creative routine.