The latest reports from rumor site Sony Alpha Rumors suggest that the new Sony A7 IV will not shoot 4K 60p video as previously hoped, but will instead capture 4K 30p downsampled from 7K.
This would be a disappointment. Over the past few years, Sony has produced a near-endless succession of 4K mirrorless cameras (we count 11!) which top out at a frame rate of 30fps. In 2021 (or even 2022, if we have to wait that long for the A7 IV), 4K 30p capture would surely be headline news for all the WRONG reasons.
Why do we need 4K 60p video?
It’s true that not every filmmaker even needs 4K, and 60p video is useful principally for slow motion effects that can be achieved on most cameras simply by swapping to full HD capture – where frame rates of 120p or even 240p are becoming common (that’s 4x and 8x slow motion respectively). So you might argue that the audience that needs both 4K capture and 60p is relatively small.
However, the resolution and frame rate of any camera is a good barometer of its sensor readout and processing speed, which is related to the codecs, frame rates and bit depths available, together with the rolling shutter or ‘jello’ effects you tend to see with older sensors.
Not only that, 60p capture and playback does give some advantages for fast-moving action and maintaining a 180-degree shutter angle (for filmmaking buffs) at faster shutter speeds in bright light, even if some videographers don't like the high frame rate 'look'.
If the A7 IV does offer 4K 30p capture again, then Sony might say it’s all the market asks for. Others might begin to wonder if it’s all that the Sony tech is capable of.
There is, of course, the Sony A7S III. This camera takes a massive leap to 4K 120p capture with 10-bit 4:2:2 internal recording. But this is a camera that uses a custom 12MP sensor barely adequate for stills, and has a price tag of $3,500/£3,800. Competent as it is, there is a huge gulf between the capabilities and the price of the Sony A7 III (and the unambitious A7C, for that matter) and the A7S III, and so far we’ve seen little sign that Sony is able to fill it.
What cameras CAN shoot 4K 60p?
If you want a faster 4K frame rate from a Sony, you have to take a giant step to the Sony A7S III, which is more than twice the price. (We could bring the 8K Sony A1 into this, but at $6,500, let’s not even go there.)
So what can we expect from the Sony A7 IV?
The current talk is that the Sony A7 IV will have a 33MP sensor (or in the 30-33MP range), that it will cost slightly more than the A7 III but not excessively so, that a couple of corners may be cut in the viewfinder and LCD specs… and that’s about as much as anyone seems to know, apart from the fact we’ve been expecting it for around a year and a half.
Originally it was thought that the Sony A7 IV would also shoot 4K 60p video, but the latest rumor, if true, suggests that it will capture 40K 30p video instead, like so many Sony cameras before.
The idea of a jump in resolution to 33MP is enough to keep the anticipation levels high, and it’s hard to imagine Sony’s AF systems could get much better, so we have no doubt that the Sony A7 IV will be as competent and popular as an all-rounder as the Sony A7 III is now – but unless some dramatic new specifications emerge, the excitement around the Sony A7 IV could be starting to dwindle.
It's possible that the reason we've waited so long for the A7 IV is not because it's a technological breakthrough but because it's a relatively low-key upgrade that can wait.