Open Gate allows you to capture a camera’s entire sensor, then crop it later for delivery to multiple different aspect ratios. Some cameras, like the Lumix GH5/6/7, have offered 4:3 open gate for years (5760×4320 on the GH6/7) and it’s my default resolution of choice for interviews. Some Canon cameras, like the newer EOS C50, can capture 7K across in a 3:2 aspect, and the latest iPhone 17 Pro and Pro Max have joined the party with 4224×3024 4:3 open gate recording in ProRes RAW.

If playing with aspect ratios is new to you, here’s an article all about it.

Why would you want to shoot taller than normal, and are there any limitations to be aware of? Let’s discuss.

Reason 1: Aspect Ratio Flexibility

If you’re delivering to widescreen and then to portrait, shooting with a taller frame than usual makes it much easier to frame for both aspects in a single shot. In theory, you don’t need open gate for this, you just need to shoot wider than you normally would, in a resolution higher than you want to deliver, and then you can crop in on a captured widescreen frame for both deliverables. In practice, open gate capture means you don’t need to shoot wider to capture that extra height.

Reason 2: Headroom for reframing

Another big reason becomes clear if you need to interview several people in the same location. With a taller-than-normal open gate, you don’t have to move your camera(s) up and down to accommodate subjects of different heights — just frame for your tallest subject.

In post, with no resolution compromises, you can keep eyelines and/or the space above your subjects’ heads consistent across all your shots. This is a huge time-saver on set, especially given that many tripods don’t make minor height adjustments straightforward.

Reason 3: Anamorphic lenses

If you’re a fan of super-wide lens flares and cinematic history, anamorphic lenses work well with 4:3 recording. An anamorphic lens stretches the image out (perhaps 1.33x or 1.5x) to use every pixel of a 4:3 frame, making the most of each 35mm film frame and bringing unique distortion characteristics and subject separation that many film fans love.

Anamorphic lenses have been popular for decades and are still popular now, but they’ll always make your image wider. If you add a 1.33x anamorphic to a 16:9 frame, you’ll end up with a cinemascope (2.37:1) deliverable. If you want anamorphic characteristics but you don’t want an image that wide, using the same 1.33x anamorphic with a taller open gate sensor will capture an image with more or the sensor and produce a less-wide deliverable.

You can also use a 2x anamorphic with a 4:3 sensor if you want to deliver 2.35:1 and crop as little of the image as possible. It’s all maths, and you’ll need to match the characteristics of your lenses, sensor and delivery aspect to get the results you want.

Not all open gate cameras are 4:3, though. Many modern mirrorless cameras have 3:2 sensors, and because this isn’t tall as 4:3, it’s useful, but not as dramatic a shift from 16:9. But some cameras are even taller than 4:3. A Blackmagic Cinema Camera 6K can shoot 4.8K in a 6:5 ratio (4832×4032) so the maths work a little differently. The basics still apply, though: a 1.33x anamorphic gives a less wide image than a 2x anamorphic, and at the end of the day you can crop and zoom to make the perfect frame if you need to. 

When shooting anamorphic on a camera with explicit support, you shouldn’t have to monitor a vertically stretched image. On a GH7 or other “real” camera, you can activate anamorphic desqueeze to match the lens setup you’re working with, and Blackmagic Camera on iPhone offers Anamorphic De-Squeeze in its settings too. De-squeeze should make content captured with an anamorphic lens look like regular spherical footage in the field, but in post, you’ll probably want to stretch your footage manually.

Reason 4: Trendy retro 4:3 delivery

While I may not have any fondness for 4:3 delivery myself (pan and scan ruined most movies I saw in my childhood and it’s all 4:3’s fault) it’s certainly popular for among music videos and some advertising. Sure, it’s a bit like IMAX, but on a 16:9 TV it simply means black bars on the sides.

Here’s a current music video delivered in 4:3, and another.

Still, if your director decides to shoot and deliver in 4:3, you can make life easier by shooting open gate on a camera that supports it. All the on-set previews will be correctly framed, and you can then simply throw your footage into a 4:3 timeline in the edit, or into a 16:9 timeline cropped by masks if that’s easier.

Open Gate limitations on iPhone

The only officially supported format for full resolution open gate recording on iPhone is with ProRes RAW. Using Blackmagic Camera or Final Cut Camera, to record in ProRes RAW you must record to an external SSD and disable stabilisation, and you’ll then be able to capture in 4224×3024 glorious pixels, taking up about 1GB space every 7 seconds or so. Very oddly, there’s actually more data captured around the edges of that 4:3 frame, especially in the corners:

Colossal data rates aren’t a problem for anyone with storage to burn and a budget for more fast SSDs, but you’ll notice the space going significantly faster. Still, stabilisation’s absence really hurts. Even on a gimbal, handheld footage shot on the 4x lens is unusably shaky; you can’t just run-and-gun when shooting ProRes RAW on an iPhone.

Blackmagic Camera does allow you to change the codec to HEVC while still recording in Log, in the open gate aspect ratio, but the resolution takes a big step down to 1920×1440 if you shoot in Log rather than Rec 709. If you were hoping to reframe to 1080×1920 portrait, that’s not enough; you’d get more pixels stepping back and shooting regular 4K at 16:9.

OpenCam is a third-party app that focuses on open gate recording, and it suffers from the same limitations as Blackmagic Camera. Though it can record in 4032×3024 in 4:3, that’s only possible in SDR, not Log. Sadly, this mode includes all the sharpening that the regular Camera app does, which rules it out for me. If you want to shoot Log, you’re thrown back to the same 1920×1440 resolution that Blackmagic Camera offers.

According to the OpenCam developers, this is a limitation of the current APIs, but it’s a real shame. To me, there’s not a lot of point in shooting low-resolution open gate; you need more than 2000px vertically to deliver 1080×1920 portrait and more than 2160px vertically for flexibility in reframing for UHD.

One other tidbit: you may have thought the front sensor on the new iPhone would be an ideal candidate for open gate recording. After all, it switches seamlessly between portrait and landscape no matter how the phone is held, so it must be a square sensor, right? Nope — it’s missing the corners. If you record a square image with the front sensor (which OpenCam can do) it’s missing edges that the 16:9 and 9:16 aspects can capture. As far as I know, there’s no way to actually capture the whole sensor, and if you could, the corners would be missing.

What about a traditional camera?

Open Gate on a GH7 

Yes, it’s larger and heavier than a phone, but the ability to shoot 5760x4320px open gate at 200Mbps HEVC with stabilisation is ridiculously helpful. I can run-and-gun this if I need to, and there’s a lower resolution 4352×3264 4:3 mode that supports slightly higher frame rates.

However, I can’t shoot in open gate at resolution in ProRes or ProRes RAW. The GH7 tops out at 5728x3024px (17:9) in ProRes RAW, and needs 2.3Gbps — or 3.5Gbps in HQ! — to store it. While that’s enough vertical pixels to reframe comfortably for UHD, I’d have to frame really, really wide to make a vertical crop work. Thankfully, HEVC is fine for most jobs I do, but it’s a shame that those wanting to shoot 4:3 in any flavour of ProRes are out of luck.

What other cameras support Open Gate?

A growing number. Panasonic (Lumix), Blackmagic and Fuji all support open gate, though support varies by camera. The crop sensor Lumix GH7 supports 4:3 capture, while most full frame sensors use a 3:2 native aspect. Canon has seen the light and are starting to incorporate open gate more, as are Sony. High end cinema cameras can usually offer open gate, but RED cameras tend to have wider native sensors and can’t give you extra height.

Modern action cameras from Insta360, DJI and GoPro also offer open gate recording, sometimes in 1:1 or 8:7 aspects, and of course 360° cameras capture everything around them.

Conclusion

There’s a bit of noise about open gate in filmmaking circles right now, from a few different perspectives. Extra height is great for reframing in landscape, for adapting to portrait, and for fans of anamorphic lenses and adapters. While I’m lucky enough to have been shooting this way for many years now (since the GH5!) I’m very glad it’s becoming more widely available on more cameras today.

If you have a modern camera, there’s a good chance it supports some form of open gate. Grab a few test shots, see if it works for you, and try to grow just a little more comfortable making the final crop in post.

Look for another article soon about the post-production side of open gate.