March of the Pixels

The Sony Alpha A7R IV is the only full frame camera yet with a resolution of 61MP, bringing it into the market space of budget medium format cameras. K Madhavan Pillai finds out if the fourth generation of Sony’s popular resolution-oriented A7R series recaptures the thrill its predecessors evoked.

- K Madhavan Pillai

Especially for those times when pixel counts fall short, the Sony A7R IV is here to make a statement. Depending on how you see it though... numerically, 61MP is about a 44% increase in resolution over the A7R III and II (and the current full frame resolution frontrunner, the Nikon D850), but in terms of the difference this makes in print size, it is less than 20% in width and height, or diagonal. However, given the same print size, a 20% bump up in pixel level detail is important for many kinds of photographers, and so are the consequent benefits of being able to make tighter crops, using different image formats (new in the A7R IV), or using its APS-C crop mode, with a respectable 26MP, for better reach.

Features Rather than the addition of technology that made the A7R III a big, exciting leap over the II, the changes in the IV over the III is more incremental and subtle, but it makes the IV a significantly more refined camera. To begin with, the 61MP back-illuminated CMOS sensor and the new processor is designed to enhance dynamic range (a huge 15 stops at ISO 100), and reduce noise while delivering detail, especially at low-to-mid ISO settings.

Extremely high resolutions also have the effect of making shooting errors, especially camera shake, very apparent. The 5-axis sensor shift IS (5.5 stops), that the A7R IV inherits from the III, is especially useful in keeping images shake-free.

If 61MP seems insufficient, the A7R IV now includes a 16-shot Pixel Shift Shooting mode (in addition to the 4-shot mode from the A7R III) that makes 16 consecutively shot images, each image made with the sensor shifting by half a pixel. The 16 images then need to be combined externally (unfortunately not in-camera), using Sony’s Imaging Edge software, to produce a 240MP photograph. The Pixel Shift mode can only be used to photograph subjects that are absolutely still during the exposures, and necessitates the use of a tripod.