Sony Alpha a7R II

Manufacturer: Sony
Type: camera — full-frame mirrorless
Year introduced: 2015
Sensor: 42.4MP back-side-illuminated Exmor R CMOS (world’s first full-frame BSI sensor)
Key specs: 399 focal-plane phase-detection AF points, 25 contrast AF points, 5-axis in-body image stabilization, 4K UHD internal video (Super 35mm and full-frame), silent shooting, no optical low-pass filter
ISO range: 100–25600 (expandable 50–102,400)
Continuous shooting: 5 fps with AF/AE tracking
Shutter durability: ~500,000 cycles
Viewfinder: XGA OLED Tru-Finder, 0.78x magnification (world’s highest at launch)
Price at launch: $3,200 USD

Overview

The Sony a7R II is a 42.4-megapixel full-frame mirrorless camera announced on June 10, 2015 (^[1]). Sony described it as their “new flagship full-frame mirrorless camera,” and it featured the world’s first back-side-illuminated full-frame Exmor R CMOS sensor — a landmark achievement that combined high resolution with high sensitivity in a way that previously forced photographers to choose one or the other (^[2]).

The BSI sensor architecture used gapless on-chip lens design, AR coating on the sensor glass seal, and copper wiring to achieve approximately 3.5x faster data output compared to the original a7R. On-sensor phase detection covered 399 focal-plane points — the widest AF coverage on a full-frame sensor at the time — providing AF speeds up to 40% faster than the original a7R (^[3]).

The camera borrowed the acclaimed 5-axis in-body image stabilization system from the a7 II, fine-tuned for 42.4MP shooting, providing approximately 4.5 stops of compensation. It also introduced a redesigned shutter with 50% less vibration than its predecessor, plus a silent shooting mode with zero shutter vibration (^[4]).

The a7R II became available in August 2015 at $3,200 USD (^[5]).

Significance for Underwater Photography

The a7R II represented a pivotal moment in the transition from DSLRs to mirrorless cameras for underwater photography. The Sony a7-series offered full-frame image quality in a smaller, lighter package than equivalent DSLRs, and the a7R II specifically triggered a housing race from every major underwater housing manufacturer.

For underwater shooters, the camera offered several compelling advantages:

• 4K video in full-frame and Super 35mm modes — the first digital camera to offer in-camera full-frame 4K recording. In Super 35mm mode, the camera oversampled from ~1.8x as many pixels as 4K, reducing moire and artifacts. S-Log2 gamma and professional picture profiles made it attractive for serious underwater videography (^[6]).
• Hybrid stills/video capability — Aquatica specifically noted that the a7R II could alternate between stills and video “directly, without the need to switch, rotate or flip a lever,” a practical advantage in underwater housings where control access is limited (^[7]).
• Compact body — the mirrorless design eliminated the mirror mechanism, producing a slimmer body that enabled smaller housings, a significant benefit for travel and in-water handling (^[8]).
• Lens versatility — Sony FE-mount lenses plus compatibility with Canon EF lenses via Metabones adapter (providing both aperture and autofocus control), and even legacy Nikonos water-contact lenses on the full-frame sensor (^[9]).
• DxOMark score of 98 — placing it among the highest-scoring sensors available to photographers at the time, just behind the RED Helium 8K (108) and RED Epic Dragon (101), and ahead of the Nikon D810 (97) (^[10]).

However, the Wetpixel community identified significant limitations:

• Battery life — the small NP-FW50 battery was a persistent concern. Forum users reported that macro shooting with the 90mm lens drained batteries particularly fast due to intensive autofocus activity. Multiple threads discussed workarounds including Nauticam’s external battery pack, though using it precluded fiber optic flash triggers due to space constraints — users had to switch to sync cords routed through accessory ports (^[11], ^[12]).
• Fisheye lens limitations — Wetpixel editor Adam Hanlon identified the lack of a decent native fisheye option as the “end of the discussion” for wide-angle underwater shooters considering the a7R II. Users could adapt Canon’s 8-15mm fisheye via Metabones adapter, but AF performance suffered (^[13]).
• Autofocus quirks — community member Paul Kay reported that the camera was “a frustrating camera” that was “happy to focus on suspended matter” and difficult to persuade otherwise, particularly in UK waters with sediment. Forum member JackConnick noted that AF with adapted Canon lenses was “even slower” and that macro autofocus could be “jumpy,” often requiring manual focus (^[14]).
• Housing size offset — despite the smaller camera body, underwater rigs still required full-frame-sized ports, dome ports, and extensions, reducing the size advantage. JackConnick observed: “You have to use a port adapter, extension and mid-sized DSLR sized ports on the a7II. So what are you really saving?” (^[15]).

Firmware Updates

In September 2015, Sony announced that uncompressed 14-bit RAW still image capture would be added to the a7R II via firmware update, following customer feedback. The feature was initially launched on the a7S II and then extended to the a7R II, offering selectable compressed or uncompressed 14-bit RAW output — a capability widely requested by photo and video enthusiasts (^[16]).

Housing Ecosystem

The a7R II shared its body dimensions with the a7 II and a7S II, meaning housings designed for the a7 II family generally accommodated all three variants. Six major housing manufacturers supported the camera within its first year:

Nauticam NA-A7II

• Price: $2,750 (without bulkhead) / $2,850 (with Nikonos bulkhead)
• Shipping: March 6, 2015 (for a7 II; compatible with a7R II)
• Material: Aluminum, 100m depth rating
• Weight: 2.35 kg with handles
• Features: Lever controls for AF-ON, review, and record; EVF/LCD switch; pull-out zoom/focus dial; integrated vacuum monitoring and leak detection; optical strobe connectors; M16 bulkhead port for HDMI or Nikonos sync cable; Nauticam Mini Flash Trigger option for Sony
• Port system: N100, with support for the Sony FE 16-35mm f/4 ZA OSS (via Nauticam 180mm dome), Sony FE 90mm macro, and Canon lenses via Metabones adapter. Also supported legacy Nikonos water-contact lenses (Sea & Sea 12mm, Nikonos 15mm) on the full-frame sensor
• Accessories: 180-degree and 45-degree enlarging viewfinders, M14 vacuum valve, Super Macro Converter

(^[17])

Sea & Sea MDX-a7II

• Price: $2,895.95 (special introductory price)
• Shipping: Early May 2015
• Material: Machined corrosion-resistant aluminum alloy, 100m depth rating
• Weight: 2,250g (housing only), 1,860g without grips
• Features: Internal Optical YS-Converter (converts TTL signal to optical for fiber optic strobe triggering); ML-NX Conversion Ring 30 for compatibility with NX ports in addition to ML ports; luminescent buttons; diopter adjustment dial; movable focus and zoom gear; 10-degree LCD tilt; built-in leak detector; two fiber-optic sockets; one N-Type 2-pin connector and one HDMI accessory port

(^[18])

Subal Alpha 7

• Price: $2,850
• Shipping: End of April 2015
• Material: Machined single-block seawater-resistant aluminum with patented hard-coat anodizing and 3-layer powder coating
• Depth rating: 80m standard, 120m TEC version on request
• Weight: 1.46 kg without grips
• Features: Compatible with Sony a7, a7R, and a7S (identical body design); Type 2 bayonet port mount; SUBAL Quick Lock closure system; leak alarm standard; electronic or fiber optic strobe triggering; GSV 180-degree and WSV 45-degree rotatable viewfinder options; wet diopter lenses (+5 to +25)
• Supported lenses: Sony FE 16-35mm f/4 ZA OSS, Sony FE 90mm f/2.8 Macro, Sony Zeiss 35mm f/2.8, Sony FE 24-70mm f/4, Sony FE 28-70mm f/3.5-5.6

(^[19])

Aquatica A7R II

• Price: $2,699 (same price for all strobe connector configurations)
• Announced: October 30, 2015
• Material: 6061 T6 aluminum (aerospace-grade) with MIL-A-8625 Type 2 anodizing and AAMA 2603-98 polyester powder coating
• Depth rating: 90m or 130m at no extra charge
• Features: Designed specifically for a7R II (also compatible with a7S II); exclusive rear rotary dial control for quick ISO access; extenders for SET and C1 buttons; strobe triggering via optical (with included LED trigger relay powered by CR2450 batteries, ~4,000-5,000 flashes), dual Nikonos, or single Ikelite bulkheads; compatible with full Aquatica DSLR port range; Surveyor moisture and vacuum monitoring sensor; stainless steel latches with safety tabs; Type 304 stainless steel controls
• Notable design point: Aquatica specifically highlighted that existing DSLR port, extension, and viewfinder owners could migrate their accessories directly to this housing

(^[20])

Ikelite for Sony Alpha a7 II / a7R II / a7S II

• Shipping: December 21, 2015
• Material: New grey polycarbonate and acrylic (announced at DEMA 2015)
• Depth rating: 200 ft (60m)
• Weight: 5 lb (2.3 kg) without tray and handles
• Features: Camera-specific TTL flash encoding for a7 II, a7R II, and a7S II; slide-in front-loading camera tray; laser-engraved rear pushbutton controls; corrosion-proof transparent construction for visible sealing surfaces; Ikelite bulkhead connector with integrated TTL circuitry
• Lens compatibility: Sony, Canon, Sigma lenses, and Metabones adaptors
• Known issues: Forum users reported problems with the first-generation Ikelite a7 housing including F-stop scroller misalignment, buttons sticking under pressure at depth, and record button jamming against the camera body (^[21])

(^[22])

Seacam Compact Sony A7II

• Shipping: January 20, 2016
• Material: Milled saltwater-proof light metal alloy, double-hardened and high-value anodized, in distinctive Seacam silver design
• Depth rating: 80m
• Weight: 1,600g excluding port and viewfinder
• Features: First housing in Seacam’s new “compact” series for mirrorless cameras; titanium Safety Lock fastening system; double O-ring sealing on all shafts and press buttons; full compatibility with Seacam port system; electronic strobe triggering with optional optical trigger and dual fiber connection; 30-degree tilted viewfinder display with integrated sunshade; 2 flash sockets (N5 or S6); vacuum test optional

(^[23])

Additional Housing Options

• Ikelite for Sony Alpha a7/a7R/a7S (first generation) — Released March 2016 at $1,500, using white and clear polycarbonate with TTL encoding. Offered as a budget option for first-generation a7 bodies (^[24]).
• Meikon — Budget housing used by some community members, with single wired connector bulkhead. UW-Technics TTL converters became available for it in Meikon-mount versions (^[25]).

Lens Options Underwater

The Sony FE lens ecosystem matured rapidly during the a7R II’s lifespan. At launch, Sony had 12 native FE full-frame lenses, with plans to expand to 20 by early 2016. Key underwater lens combinations included:

• Sony Vario-Tessar T FE 16-35mm f/4 ZA OSS* — the primary wide-angle rectilinear zoom for underwater use, described by Nauticam as “a game changer.” Best results with 180mm+ dome ports, though some users preferred 230mm domes. Required stopping down to f/11-16 for sharp corners (^[26], ^[27]).
• Sony FE 90mm f/2.8 Macro G OSS — the primary macro lens, providing 1:1 magnification. Noted for intensive AF power draw that reduced battery life (^[28], ^[29]).
• Canon EF 8-15mm f/4L Fisheye USM via Metabones adapter — the most common fisheye solution, though AF performance was slower than native. Some community members shot successfully with this combination for years (^[30], ^[31]).
• Canon EF 100mm f/2.8L Macro IS USM and EF 16-35mm f/2.8L II USM — additional Canon lenses used via adapter (^[32]).
• Sigma Art 20mm f/1.4 — reviewed underwater on the a7R II by freediver Daan Verhoeven via Metabones adapter in a Nauticam housing, praised for “creamy, blurry backgrounds and buttery bokeh” for underwater portraits, though noted as specialized rather than a general-purpose lens (^[33]).
• Nikonos water-contact lenses — the Sea & Sea 12mm fisheye and Nikonos 15mm could be used directly on the full-frame sensor, bringing legacy lenses back into service (^[34]).
• Nauticam WWL-1 wet lens — used with the Sony 28mm f/2 as a compact wide-angle solution, avoiding the need for large dome ports (^[35]).

Reviews & Coverage

• Phil Rudin reviewed the a7R II with the Ikelite housing in UwP Magazine Issue 90 (May/June 2016), and was also referenced in multiple forum discussions as an authority on the camera’s underwater capabilities (^[36], ^[37]).
• JackConnick published a comparison article on his blog: “Sony a7II and Sea & Sea MDX-A7II Housing System Review,” also covering Micro 4/3 vs APS-C vs full-frame comparisons (^[38]).
• The Atomos Ninja Assassin recorder/monitor ($1,295) was announced in September 2015 as a companion device aimed at mirrorless shooters, offering 4K UHD 4:2:2 10-bit recording via HDMI for the a7R II’s clean HDMI output (^[39]).

Community Discussion

The a7R II generated extensive discussion in the Wetpixel forums, reflecting the broader DSLR-to-mirrorless transition debate:

• “Thoughts: Sony A7R II from D810” (25 replies) — A photographer considering switching from the Nikon D810 to the a7R II received mixed advice. Benefits cited included smaller housing, 4K video, and competitive AF. Negatives included battery life, fisheye lens limitations, and the observation that housing+port size negated much of the body size advantage. The thread ended with the original poster opting for a Nikon D850 instead (^[40]).
• “External battery for Aquatica housing Sony a7R II” (7 replies) — Users discussed battery drain during macro shooting. Aquatica’s Carolina A confirmed the company was developing an internal external battery solution. Phil Rudin pointed users to Reef Photo’s battery pack solution (^[41]).
• “What’s more valuable, Autofocus vs resolving power?” (32 replies) — A photographer choosing between the a6400 and a7R II for macro work was advised that the a7R III had “much better autofocus compared to the a7RII” and that Sony was not investing in new APS-C lenses. Multiple respondents recommended Micro 4/3 systems instead for macro work (^[42]).
• “Which full frame camera would you choose?” (39 replies) — Adam Hanlon’s 2019 survey revealed that most Wetpixel community members still preferred the Nikon D850 for underwater stills, with the Sony mirrorless system gaining ground but not yet dominant. Respondents noted that Canon’s auto white balance was superior to Sony’s for ambient-light video work (^[43]).
• “Do you shoot with Sony a7 or a9 series?” (53 replies) — By 2021, Sony users reported shooting with a7R II, a7R IV, a7S III, and other models. The Sony 16-35mm f/4 and Canon 8-15mm fisheye via MC-11 adapter were the most popular wide-angle choices. The Nauticam WWL-1 with Sony 28mm f/2 emerged as an increasingly popular compact wide-angle alternative (^[44]).
• TTL systems discussion (100 replies) — The a7R II was used with UW-Technics TTL converters in both Meikon and major manufacturer housings. Pavel Kolpakov led extensive technical discussions about TTL implementation for Sony cameras (^[45]).

Context: The a7 Series Lineage

The a7R II was the fifth camera in Sony’s full-frame mirrorless lineup, which began with the a7 and a7R in October 2013 — the “smallest and lightest full frame interchangeable lensed cameras on the market” at 24MP and 36MP respectively (^[46]). The a7 II followed in November 2014, adding 5-axis IBIS and improved AF (^[47]). Nauticam was the first major housing manufacturer to support the Sony full-frame mirrorless system, announcing the NA-7 for the a7/a7R in January 2014 at $2,850 (^[48]).

The a7R II was succeeded by the a7R III in October 2017, which doubled battery life, improved AF to 10 fps continuous shooting with full AF/AE tracking, and maintained the same 42.4MP BSI sensor. The a7R III’s improved battery life directly addressed the a7R II’s biggest underwater limitation (^[49]).

Timeline

• 2013-10-16: Sony releases the a7 and a7R, first full-frame mirrorless cameras (^[50])
• 2014-01-08: Nauticam announces NA-7 housing for a7/a7R (^[51])
• 2014-11-25: Sony announces the a7 II with 5-axis IBIS (^[52])
• 2015-03-06: Nauticam ships NA-A7II housing for a7 II family ($2,750/$2,850) (^[53])
• 2015-03-30: Subal announces Alpha 7 housing ($2,850) (^[54])
• 2015-05-01: Sea & Sea announces MDX-a7II housing ($2,895.95) (^[55])
• 2015-06-10: Sony announces the a7R II (^[56])
• 2015-08: a7R II available at $3,200 (^[57])
• 2015-09-15: Sony announces uncompressed 14-bit RAW firmware update for a7R II (^[58])
• 2015-10-30: Aquatica announces A7R II housing ($2,699) (^[59])
• 2015-12-21: Ikelite ships housing for a7 II / a7R II / a7S II with TTL (^[60])
• 2016-01-20: Seacam announces compact housing for a7 II R/S (^[61])
• 2016-03-10: Ikelite releases housing for original a7/a7R/a7S ($1,500) (^[62])
• 2016-05: Phil Rudin reviews a7R II with Ikelite housing in UwP Magazine Issue 90 (^[63])
• 2016-08-29: Daan Verhoeven reviews Sigma 20mm f/1.4 Art underwater on a7R II (^[64])
• 2017-01-11: DxOMark references a7R II score of 98, just below RED Helium 8K (108) (^[65])
• 2017-10-25: Sony announces a7R III successor with doubled battery life (^[66])

References