First look & review of the G7X Mark III underwater

A first look at the Canon G7X Mark III’s underwater performance, ergonomics, and updates to the G7X Mark II
By Nirupam Nigam

The Canon G7X Mark III is a first-rate camera in a compact body. As an upgrade from the G7X Mark II, the Mark III incorporates a similar sensor and the same lens, but there have been significant improvements to the camera’s processing capabilities. Most notably, a “stacked” sensor and a DIGIC 8 image processor. 

These hardware updates have resulted in an improved burst shooting rate (now 20 fps), 4K video capability (no crop), improved image buffer (now 70 shot RAW), and slow-motion video. Although image quality will likely remain the same, these improvements will give underwater photographers new tools below the waves to create their artwork. 

The G7X Mark II has dominated the compact camera market for the last twoish years. But a lot of has happened in two years, especially when you look at Canon’s competitors – the Sony RX 100 V/VA and the Sony RX100 VI. That being said, the G7X Mark III is definitely the camera to bring Canon back to the future. We can’t wait to take this camera underwater and put it to the test.

U.S. MSRP Canon G7X Mark III: $750


Canon G7X Mark III

Canon G7X III compared with G7X II

The upgrades on the Canon G7X Mark III from the G7X Mark II will be welcomed mostly by video-oriented compact shooters and vloggers. However, there are a few improvements made to the camera that are exciting for underwater photography – most notably when it comes to 4K video, slow motion video, burst shooting, buffer, and the new stacked CMOS sensor. 


Canon G7X Mark III Specifications


Key Upgrades from the G7X Mark II

4K video @ 30fps and 1080p @ 120 fps

Built-in Bluetooth and WiFi

Ability to shoot panoramas

External microphone jack

20 fps burst mode (upgraded from 8fps)

70 shot RAW buffer (upgraded from 21 shots)

Ultra-fast electronic shutter for shooting wide open aperture in daylight – 1/25,600s

Slow motion video (120 fps in 1080p)

Supports vertical video shooting (not for live-streaming)

Supports live streaming videos to YouTube

Cheaper than the Canon G7X Mark II on release date

New stacked CMOS sensor

DIGIC 8 image processor


Additional Key Canon G7X Mark III specs

20.1 megapixel 1.0” stacked CMOS sensor

DIGIC 8 image processor

4.2x optical zoom lens (24-100m f/1.8-2.8) with optical image stabilization

3.0 inch touch panel LCD screen with tilt option of 180 degrees for selfies and vloggers

Compatible with USB charge/power supply

Contrast-detection autofocus (no dual pixel autofocus)

Clean HDMI output

Native ISO: 125 – 12,800

Size: 4.1” X 2.4 “ X 1.6 “

Weight: 11.3 oz (319 g)




Improved Video Capability

The G7X Mark III’s most exciting update by far is its new and improved video capability. 4K video capability is standard now here in 2019. Canon brought the G7X III to this standard with 4K capability at 30 fps. It’s also a relief that there is no 4K crop factor, so the full potential of the sensor is utilized resulting in excellent video details. Slow motion video capability (120 fps) is also available at 1080p. This will be great for any underwater photographer capturing quick moments underwater – like schools of fish, pelagic animals, and marine mammals. 

Beyond the many juicy features for divers, there have been some exciting updates made for topside users as well. The G7X Mark III now supports video live streaming on YouTube as well as vertical video shooting (so your video looks like it’s from a cellphone, I guess?). 


Improved Photo Capability

There are a number of improvements to the G7X Mark III’s photography capability; all of these improvements are a result of the new 1-inch stacked CMOS sensor and the DIGIC 8 processor. Although the new sensor seems similar to the sensor on the G7X Mark II, the “stacked” sensor means that it has one layer for collecting data and one layer for processing. This means the camera has more ability to process images. The G7X Mark III’s burst shooting capability has been improved from 8 fps to a whopping 20 fps. The RAW buffer has also been improved to 70 shots from 21. This is very exciting for underwater photographers who want something small that can capture ludicrously fast fish and mammals underwater. 20 fps is excellent for any compact camera and combined with a 70 shot RAW buffer, that means you can shoot RAW at 20fps for just over three second continuously before the camera needs to take a break to process. That’s perfect for getting dive bombed by a cormorant or passed by a sea lion. Unfortunately, burst shooting is only 8.3 fps when shooting with continuous AF, not that 8 fps is slow… 

Side note: The G7X Mark III now can shoot Panoramas! Not the most useful feature for underwater photographers, but very cool nonetheless. Check out our guide to shooting underwater panoramas. 


Canon G7X Mark III Key Features

Body and Build

At 4.1” X 2.4 “ X 1.6 “, the Canon G7X Mark III is a very compact camera. In fact, it weighs less than a pound. It’s hard to find many cameras smaller and more compact to bring underwater. For many divers, the size of the Mark II was one of its main selling points, and this will likely be the same for the G7X Mark III. 

It also features a 3 inch touch screen LCD that can be flipped up by 180 degrees for selfies. Canon is trying to appeal to the vlogger market with an external microphone jack and built-in WiFi/Bluetooth. 



We look forward to taking the Canon G7X Mark III underwater to test its AF capability once housings start rolling out for the camera. As of yet it sounds the Mark III shares a contrast-detect autofocus system with the Mark II. Although it’s not terrible, some people had high hopes for Canon’s famous dual pixel autofocus. We’ll just have to wait for the next iteration! 


Sensor and Image Quality

As we mentioned before, there has been an upgrade in the sensor of the G7X Mark III, but not a huge one. Although a “stacked” CMOS sensor improves image processing, it won’t necessarily improve image quality. So we expect the G7X Mark III’s image quality to be similar to the Mark II. That being said, the image quality is still excellent – 20.1 MP is impressive for any compact sensor. 

The lens on the Mark III appears to be the same as the Mark II, which means it is versatile for both wide angle and macro underwater photography – especially with wet lenses. 


G7X Mark III for Underwater Photography

The Canon G7X Mark III will be one of the best choices for underwater photo and video with a compact camera. The G7X Mark II was one of the most popular underwater compact cameras since its release in 2016 – even with competition from the Sony RX 100 V/VA and RX 100 VI. By the release of the Sony RX 100 VI, it was starting to look like the G7X Mark II was falling behind. But the G7X Mark III puts it back in 2019 with 4K video recording, quick burst modes, and large buffers. 

Ultimately, underwater photographers will benefit with upgrades in processing and have newfound ability to capture quick subjects, whether its slow motion video or burst shooting. We expect underwater controls to be similar to the Mark II with aperture and shutter speed at your fingertips and ISO one tap away. Underwater macro and underwater wide angle shooting is bound to be a joy with the G7X Mark III’s zoom lens, especially with accessories like wet diopters and wide-angle wet lenses. 


Canon G7X Mark III Underwater Lenses


Wide-Angle Wet Lenses

A wide-angle wet lens increases your field of view, which means that you get more background behind your subject and must be closer to it. This means that you will often get less water between the camera and your subject than if you did have a wide anlge lens. Less water means a clearer subject, as well as better lighting from a video light, photo light or strobe....and ultimately better colors. A wider angle also allows for more dramatic shots, especially with large subjects like oil rigs, kelp forests, large animals, reefscapes and wrecks.

We recommend using the UWL-04 fisheye lens, with its 165 degree wide angle of view will allow you to create stunning wide-angle shots. Other great options to consider are the Kraken KRL-01 and KRL-02 wet wide anglelenses, which provide 145 and 150 degree angles of view, respectively.


Macro Wet Lenses

Although the Canon G7X Mark III has a macro mode, the best option for underwater macro photography is to use a diopter. The Bluewater +7 macro lens gives very good results. We recommend stacking 2 of these lenses for supermacro.



Canon G7X Mark III Underwater Housings

Because the G7X Mark III shares dimensions with the Mark II, it’s quite possible that the Mark III will be compatible with housings for the Mark II. That being said, we won’t be able tell if this is true until manufacturers come out with the first G7X Mark III housings. We expect underwater housings from Fantasea, Ikelite, Nauticam, and Isotta. 

Be sure to keep checking these pages for major underwater housing brands for updates on the G7X Mark III's housing options:

Ikelite Canon G7X Mark III Underwater Housing


Nauticam Canon G7X Mark III Underwater Housing


Fantasea Canon G7X Mark III Underwater Housing


Sample Images from the G7X Mark II

(until housings for the G7X Mark III are released)


As the G7X Mark II and G7X Mark III have basically the same sensor (with minor differences), underwater photos will be similar. We’ll update this section once we take the G7X Mark III underwater. See our Canon G7X Mark II review for more! Thanks for reading our Canon G7X Mark III review and stay tuned for updates soon.

Below are some sample photos from shooting the Canon G7 X Mk II in the Fantasea G7XII housing.









The Canon G7X Mark III is the long-awaited successor to the highly-successful G7X Mark II. While it faces tough competition from the Sony RX100 VI and Sony RX100 V/VA, it holds its ground with the addition of 4K video, 20fps burst, and a 70 shot RAW buffer.

The new 1”  20 MP “stacked” CMOS sensor is bound to deliver great image quality with improved processing ability. What more could you ask for in such a compact underwater package? 


Nirupam Nigam is a dedicated underwater photographer and fisheries scientist. While growing up in Los Angeles he fell in love with the ocean and pursued underwater photography in the local Channel Islands. He received degrees in Aquatic and Fisheries Science and General Biology, as well as a minor in Arctic Studies, at the University of Washington. Now he works as a fisheries observer on boats in the Bering Sea and North Pacific. When he is not at sea, he is traveling with his fiancee and taking photos. Check out more of his photography at!


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