The Sony A7III may be stretching your videos – here’s how to fix it

If you’ve been shooting 4K video with your Sony A7III and thought things looked a little off, you might just be right. While shooting some footage for a video, Caleb Pike over at DSLR Video Shooter noticed that footage shot at different resolutions on the A7III wasn’t quite lining up. It seems that 4K 24fps full frame video was actually being stretched vertically.

You can see in the above shots of full frame vs super 35 crop mode, that horizontally the images line up all the way. Vertically, however, the full frame image is appears stretched.

According to Caleb’s tests, the issue only pops up if you’re shooting full frame 4K video at 24 frames per second. But that’s probably the most common setting that many people will use – it’s the format I’d use if I were shooting an A7III.

Caleb’s video goes pretty in-depth into his testing method to reproduce the issue, so if you’re interested in seeing exactly what’s going on, it’s worth a watch. And it’s not just a random glitch with Caleb’s camera. He had a number of people help him test this to see if they could reproduce the issue, and they all did.

The stretch looks quite minimal, but it’s definitely there. You may or may not notice it in your final footage in the real world, but even if you don’t notice it, others may. While it might seem like a small thing, that Caleb suggests fixing by scaling the X axis of your shot up by 1%, it’s a pretty big problem. If you’re mixing different formats footage, it may be difficult to keep track of exactly which shots you need to correct.

Caleb’s theory about what’s going on is how Sony’s resizing the images from the A7III’s 6K sensor. He believes that Sony might’ve messed up the aspect ratio calculation and it’s simply not scaling the vertical down quite as much as it needs to vs the horizontal.

If that’s the case, then it’s likely just a firmware issue and an update can fix it. Hopefully, they’ll do that soon and the Sony A7III will shoot as it should.