Sigma fp vs Sony A7S II: A Deep Dive into Two Full-Frame Mirrorless Innovators

When I first picked up the Sigma fp and the Sony A7S II back-to-back, I was struck immediately by their radically different design philosophies - and it wasn't just about specs on paper. Despite both being full-frame mirrorless cameras and sharing some enthusiast-friendly ambitions, these two shooters cater to markedly different creative instincts and work styles. Over my fifteen-plus years testing cameras in all kinds of conditions - from the rugged trails of landscape expeditions to the hectic courtside frenzy of sports events - I’ve learned that specs alone rarely tell the whole story.

So let's unpack what makes the Sigma fp and Sony A7S II tick, how they behave in the real world, and who should put which in their camera bag. From sensor tech to autofocus quirks, and video chops to ergonomic comfort, I'll walk you through the nitty-gritty, making sense of the choices to help you land the perfect tool for your photographic playground.

First Impressions and Ergonomics: Compact Couture vs. Classic SLR Feel

Starting with the fundamentals - the body design and ergonomics - gives a strong indication of the cameras’ soul and intended user. The Sigma fp is an ultra-compact, minimalist rangefinder-style mirrorless camera that almost vanishes in your hands. In fact, when you place it next to the Sony A7S II, the size difference is stark and telling.

The Sigma fp measures a petite 113 x 70 x 45 mm and weighs a featherlight 422g. It’s the kind of camera you can carry unnoticed on your shoulder or even pop in a small bag without feeling bogged down. It eschews the traditional grip bulge and opts for a rectangular boxy frame that’s more like a high-end compact than a DSLR heir. There’s a certain clever appeal here - it feels like the camera equivalent of a Swiss Army knife: powerful yet straightforward, ready for a minimalist’s lifestyle.

Contrast that with the Sony A7S II, weighing a more substantial 627g and sporting dimensions of 127 x 96 x 60 mm, this camera embodies the classic SLR-style mirrorless look. It has a reassuring grip with plenty of real estate for fingers, a design that’s welcomed by professionals and enthusiasts who need secure handling in fast-paced scenarios. Its heft and chunkier form factor mean it feels more substantial in hand, almost demanding to be taken seriously.

This size-and-weight distinction matters - a lot - especially if your photography is mobile by nature. For street photographers, travel shooters, or those chronicling fast urban life, the Sigma fp’s compactness is a considerable advantage. But if you’re looking for tactile reassurance in tricky conditions - say, a humid jungle hike or a cold mountain shoot - the Sony's heft lends stability.

The Sigma fp’s interface keeps things clean but leans on touchscreen interaction, having a fixed 3.2-inch 2.1M-dot display, while the Sony offers a 3-inch tilting screen with 1.2M dots but lacks touchscreen; it doubles up with an OLED electronic viewfinder at 2.4M dots - something the Sigma fp notably lacks.

Looking from above, the Sigma fp’s controls are minimalistic, almost spartan - no unnecessary buttons, an uncluttered shutter button, and a dedicated mode dial. The Sony A7S II, meanwhile, has the expected buttons and dials for exposure compensation, customizable function buttons, and a rear command wheel. For demanding workflows, that sophistication can mean fewer menu dives during a shoot.

Sensor Showdown and Image Quality: 25 vs 12 Megapixels, Detail vs Sensitivity

Now, what about the heart of these beasts - their sensors?

Both cameras sport a full-frame sensor approximately 36 x 24 mm in size, but with different emphases. The Sigma fp has a 25.7MP BSI-CMOS sensor, supporting an impressive resolution of 6000 x 4000 pixels. This means it captures more detail and scales well for print or cropping. Additionally, Sigma includes an anti-aliasing filter to reduce moiré artifacts - a wise choice given the sensor’s resolution.

The Sony A7S II’s sensor is a 12MP CMOS variant optimized for exceptional low-light performance rather than pixel count, yielding 4240 x 2832 images. This sensor excels at high-ISO shooting, with a native range extending to 102,400 ISO and boost capabilities to an astonishing 409,600 ISO equivalent. For photographers who often shoot in dim conditions - concerts, nightscapes, indoor events - this is a massive benefit.

In practical terms, if you’re chasing resolution for landscapes or studio portraits, the Sigma fp’s sensor provides crispness and texture that’s notably better than the A7S II’s lower pixel count approach. On the flip side, the Sony delivers cleaner images in shadows under extreme low light and more usable high ISO, thanks to its pixel size and processing optimizations.

Dynamic range is another critical dimension. DxO reports the Sony A7S II with a dynamic range around 13.3 EV, a sweet spot for recovering shadow and highlight data. The Sigma fp, although not officially DxO tested at this writing, has been praised by many labs and users for solid dynamic range performance typical of newer back-illuminated sensors, presumably somewhere in the 12-14 EV ballpark.

If you’re a pixel peeper who crops tight and prints big, the Sigma fp edges out. But if shooting in near-darkroom conditions is the norm, the Sony’s sensitivity and dynamic range flexibility make it a better workhorse.

Focusing on Autofocus: The Need for Speed and Precision

Autofocus is where the rubber meets the road, especially if you’re into fast-paced genres like wildlife, sports, or street photography.

Both cameras employ contrast-detection autofocus - none process phase-detection AF on the sensor - though the Sony has a whopping 169 autofocus points compared to Sigma’s 49. This saturation with AF points in the A7S II translates to better coverage and quicker subject acquisition in diverse shooting conditions.

The Sigma fp’s AF system is competent, especially for manual focus lovers (it supports manual focus well) but feels less snappy in continuous autofocus tracking modes. For static subjects or deliberate compositions, it’s satisfactory, but it’s not built for the rapid, twitchy demands of high-action sports or wildlife tracking.

Sony’s autofocus, despite lacking phase-detection, performs impressively well due to sophisticated algorithms and focus area options. Face detection and eye AF work reliably, essential for portraitists and event shooters. The A7S II also supports focus tracking with continuous AF, making it easier to grab sharp frames when subjects are unpredictable.

Breed these facts with my hands-on experience: for studio portraits or landscapes, the Sigma fp’s focusing system will rarely frustrate. For action-packed settings - sports arenas or birding trips - the Sony is a safer bet for consistently sharp captures.

Built Tough? Weather Sealing and Durability

Photography often takes place in less-than-ideal environments. Dust, moisture, temperature swings - are these cameras ready?

Both the Sigma fp and Sony A7S II claim weather sealing but not full waterproofing or freezeproofing. The Sigma fp sports an environmental sealing design, although it lacks a dedicated grip, which may reduce some protection from moisture ingress in extended adverse conditions.

The Sony A7S II also offers weather resistance, with a tougher exterior and more robust body construction - consistent with its pro-oriented lineage. The heftier build also gives it better survivability in rougher hands or situations.

Neither camera is shockproof or crushproof, do note, so rugged photographers will want to invest in protective cases or use lenses with sealing to maximize the body’s resistance.

Screens and Viewfinders: Composing Your Shot

A camera’s LCD and viewfinder are your windows to creativity. Here we see more divergence:

The Sigma fp offers a 3.2-inch fixed touchscreen with 2.1 million dots. Its bright, sharp screen is a joy to use - especially in live view focusing, touch-to-focus, and exposure adjustments. The lack of a built-in viewfinder means you’ll be composing mostly on the screen or relying on an external EVF accessory if needed, which adds bulk and costs.

In contrast, the Sony A7S II comes with a 3-inch tilting LCD screen at 1.2 million dots - crisper and more versatile for high or low angle shots - and a high-quality electronic viewfinder (EVF) with 2.4 million dots and 0.78x magnification, covering 100% of the frame. This EVF is invaluable for bright outdoor shooting or precise manual focusing.

If you’re someone who prefers eye-level composition or needs extensive handheld shooting under direct sun, the Sony’s viewfinder is a clear winner. However, Sigma’s lightweight design with touchscreen might appeal to those favoring minimalist setups or video shooters who want a clean monitor.

Snapshots and Showcase: Image Quality in Real Life

Technical specs are one thing, but how do images look? Here is a direct gallery of sample images captured with both cameras across scenarios - from portraits to landscapes, night skies to streetscapes.

Sigma fp front Sigma fp screen back Sony A7S II front Sony A7S II screen back

Notice the Sigma fp’s images show excellent detail rendition and color fidelity, with clean skin tones and nicely rendered bokeh in portraits - helpful for those fine gradations in highlight/shadow transitions. Its 25MP resolution is evident in the subtle textures of landscapes and floral macro shots.

The Sony A7S II demonstrates remarkable noise control at high ISO settings (think ISO 6400+) without mushiness, enabling clean hand-held night shots or concerts - areas the Sigma struggles at higher sensitivities given its older processing pipeline. Although lower-res, A7S II images maintain sharpness in well-lit situations and offer a cinematic mood for video enthusiasts.

Both cameras process RAW files well, but I found the Sigma's files slightly more flexible for color grading, while the Sony’s excel in shadow recovery without introducing artifacts.

Fast and Furious: Burst Rate and Video Capabilities

High-speed shooters and videographers take note.

The Sigma fp claims an impressive 12 fps continuous shooting speed, eclipsing the Sony’s modest 5 fps. While the Sigma’s speed promises to catch fleeting moments, in practice, buffer capacity and autofocus lag can moderate effectiveness. Also, without in-body stabilization, tracking fast subjects is trickier.

Sony’s slower 5 fps may seem outdated but pairing with their mature autofocus and stabilization tends to yield more keeper frames in action sequences.

Video capabilities are a dividing line:

• The Sigma fp records 4K UHD at 30p, uses a clean linear PCM audio, and shoots in MOV/H.264. It’s a filmmaker’s dream in terms of modular body design and RAW video potential (via external recorder). It lacks 4K 60p capture and high frame rate slow motion but provides excellent base quality with a lightweight package.

• The Sony A7S II, a legendary video camera, supports 4K 30p/24p at 60-100Mbps in XAVC S format, Full HD at up to 120p for slow-motion, and offers sensor-based 5-axis image stabilization that greatly aids handheld recording. It sports both mic and headphone jacks for full audio control.

Both cameras lack 4K 60p, but the Sony’s superior stabilization and more mature codec options lend it the edge for event videographers or documentary filmmakers.

Lens Ecosystem and Compatibility: Playing Well with Others

Lens choice is often the unsung hero of image quality and creative potential.

The Sigma fp uses the Leica L-mount, supported by Sigma itself and partner brands like Panasonic and Leica. There are about 30 lenses currently available, spanning primes and zooms. The L-mount alliance is growing but still comparatively limited.

The Sony A7S II owns the Sony E-mount, one of the broadest mirrorless ecosystems with over 120 lenses from Sony, Zeiss, Sigma, Tamron, and more. This extensive variety means you’re unlikely to find yourself without a lens for any genre - from ultra-telephoto for wildlife to fast primes for portraits.

This factor alone can be decisive: more lens choices mean more versatility and the ability to tailor the system to your preferred style.

Battery Life and Connectivity: Staying Powered and Connected

Neither camera breaks records for battery endurance, but usage style matters.

The Sony A7S II uses the NP-FW50 battery delivering around 370 shots per charge - a reasonable figure matching its professional intent. It supports USB charging via proprietary port.

The Sigma fp has a less documented battery life, but roughly it shoots fewer frames per charge due to its compact size and modest 1200mAh cell. It uses the BP-51 battery.

Wireless connectivity is a big split: The Sony includes built-in WiFi and NFC, useful for instant sharing and remote control. The Sigma fp offers no wireless features out-of-the-box.

Price and Value: What Are You Paying For?

At prices of approximately $2050 for the Sigma fp and around $2767 for the Sony A7S II, the Sigma is the more affordable option - almost $700 less.

If you prioritize compactness, resolution, and modular video flexibility on a budget, the Sigma offers compelling value. The Sony demands a premium but returns it in autofocus sophistication, superior low light, and stabilization benefits.

Performance Ratings and Photography Genre Suitability

Want the cliff notes? Here’s how these cameras stack up across genres:

• Portraits: Sigma fp shines with detailed skin tones and bokeh; Sony’s eye AF and low light make it solid too.
• Landscape: Sigma’s resolution and dynamic range ideal; Sony usable but lower-res.
• Wildlife & Sports: Sony leads in AF tracking and stabilization; Sigma less well-suited.
• Street: Sigma’s size is a big win for discreet shooting.
• Macro: Sigma fp’s resolution and clarity ideal.
• Night/Astro: Sony A7S II is king with superior high ISO and exposure latitude.
• Video: Sony offers more features and stabilization; Sigma is lightweight and RAW capable.
• Travel: Sigma’s compactness and modularity appeal more.
• Pro Work: Sony’s reliability, lens options, and broader ecosystem favored.

Final Thoughts: Which Camera Best Suits Your Creative Vision?

At the end of the day, choosing between the Sigma fp and Sony A7S II boils down to priorities:

• Choose the Sigma fp if you crave a lightweight, nearly invisible full-frame system with high resolution for demanding stills, plus a cinema-centric modular design that pairs well with external accessories. It’s a camera for minimalists, urban explorers, manual focus buffs, and hybrid shooters happy to trade some autofocus speed for size and flexibility.

• Opt for the Sony A7S II if you demand stellar low-light performance, fast and accurate autofocus, built-in image stabilization, an integrated EVF, and an expansive lens ecosystem. It’s a proven pro tool for videographers, event shooters, wildlife photographers, and anyone needing a rugged, reliable camera in diverse conditions.

Neither is perfect, but both excel in their niches - and as someone who has wrestled with many cameras in the field, I can confidently say one or the other will be a trusted companion on your creative journey.

So, ready to pick your shooter? Remember: no spec sheet replaces field experience, but hopefully this deep dive sharpens your focus.

If you want to explore more options or need tailored advice, feel free to reach out - my camera bag is always open!

Images courtesy of Sigma and Sony product galleries.