Camera manufacturers used to fight for consumers with ever-higher megapixel ratings, but at some point most buyers stopped caring about the numbers.

So why has Sony stirred the pot by releasing a mass-market camera with 61 megapixels (MP)?

For camera buffs, the specifications of the firm’s a7R IV camera – which dropped into an unsuspecting market in July – made it a revelation.

The market’s previous megapixel champion was the Canon 5Ds, with a 50.6MP sensor – but that camera is a full-sized digital SLR (DSLR), making it bigger and heavier than Sony’s mirrorless design.

Take it to the limit

Sony supplies camera sensors to around 40 per cent of the camera market, but in recent years it has won accolades after building cameras around new full-frame sensor designs that differentiate its products from its rivals.

“Sheer resolution has always been an important aspect of image quality,” Sony Australia senior product specialist Sean Ellwood told Information Age, “but around the 24MP level we reached a point of sufficiency for a lot of people.”

While most manufacturers had peaked in the 20MP to 24MP range, Sony last year pushed its popular a7R III to 42.3MP – and its latest upgrade represents a 50 percent boost on that figure.

The increase is due as much to technical reasons as marketing strategies, says Richard Butler, technical editor with camera-review giant

“Generally, pixel counts have gone up when technology has allowed them to,” he explains, noting that the megapixel race “has always been active, though the trend towards full frame makes it look more dramatic than it is. Even a 4K video only requires around 8MP of data.”

Sensor and sensibility

As resolution increases, cameras need ever more-powerful processors to handle ever-larger volumes of image data.

Casual snappers won’t notice, but professionals shooting dozens of pictures in succession often wait for their camera to catch up as it applies image enhancement, converts images to JPEG, and writes the data to a storage card.

Putting a faster CPU in the camera speeds these processes, but reduces battery life and usability – another limitation that has kept smartphone makers from pushing their resolution counts much higher.

Increasing resolution has largely been limited by diminishing returns: most users are content with the 12MP or 16MP cameras in their iPhones, so there was no point cramming larger and more power-hungry sensors into smartphones’ tiny bodies.

Instead, smartphone makers focused on features such as new depth-simulating portrait modes and multiple fixed lenses (Samsung’s Galaxy A9 has four lenses) for wide-angle and zoom photography.

Conventional fixed-lens cameras, however, need to figure out other tricks – and better sensors are still a drawcard for high-end buyers that appreciate their value in numerous situations.

Wildlife photographers, for example, need as many pixels as they can get because they often crop their pictures hard to focus on a single animal.

Yet higher resolution can also improve overall results by reducing aliasing and improving colour accuracy.

“Most sensors only capture one of their three primary colours at each pixel,” Butler explains, “therefore the more pixels you have, the lower the risk of coloured detail in the scene falling awkwardly between the gaps between same-coloured pixels on your sensor.”

Looking beyond resolution

Having decisively captured the megapixel crown – for now – Sony may have single-handedly revived the megapixel wars.

Canon is said to be readying a mirrorless rival built around a sensor north of 80MP, while Fujifilm’s GFX100 102MP medium-format camera had cameraphiles breaking their piggybanks and 100MP offerings from Hasselblad and Phase One cost as much as your average 4WD.

By comparison, the $5000-plus price tag on Sony’s latest camera brings it within range of enthusiast photographers – and that could once again make megapixels a talking point in the run-up to the Christmas gift-giving season.

“With the rise of the smartphone, photography is more popular than ever – yet while convenience is king in a lot of situations, megapixels never stopped being something that people were interested in,” Ellwood said.

“As the technology gets better and better, we can expect that trend will continue. Resolution is a big number that we can all pay attention to and has a very clear meaning, but there are other interesting and more exciting things we can do.”