Why do some cameras crop in 4K mode?
Some cameras crop the image in 4K because they cannot read the full sensor fast enough to deliver 4K video. Instead of reading all pixels and downscaling, they read only a smaller central portion — effectively turning your full frame camera into an APS-C or even MFT camera during video recording.
Why full sensor readout is difficult
A 4K frame contains 8.3 million pixels. At 30fps, the camera must process 249 million pixels per second. At 60fps, that doubles to 498 million.
A 24MP sensor has 24 million pixels per frame. Reading all 24 million and downscaling to 8.3 million (oversampling) produces the best quality — but requires enormous processing power and generates significant heat.
Many cameras lack the processing power or thermal headroom to oversample, so they take a shortcut: read only 8.3 million pixels from the center of the sensor. This is the crop.
How crop affects your shooting
Field of view narrows: A 24mm wide-angle lens behaves like a 36mm (with 1.5x crop) or even 48mm (with 2x crop). Your wide-angle shots become standard shots.
Depth of field deepens: The effective crop factor gives you deeper depth of field — harder to achieve that shallow cinematic blur.
Lens planning changes: You need wider lenses to compensate. An ultra-wide 16mm becomes essential if your camera crops in 4K.
Quality varies: Cropped 4K from line-skipping is lower quality than oversampled 4K from full readout.
Full-readout 4K cameras at Camera Shop Egypt
Cameras that avoid the crop
Premium cameras with powerful processors and stacked sensors can read the full sensor and oversample to 4K — no crop.
Canon EOS R5 / R6 II: Full-width readout in most 4K modes. Slight crop only in 4K 60fps.
Sony A7 IV / A7C II: Full-width 4K 30fps. Crop in 4K 60fps.
Sony FX30 / FX3: Full sensor readout with oversampling in 4K — designed for video.
Always check your camera’s specific recording modes — crop behavior can vary between 4K 24fps, 4K 60fps, and 4K 120fps.
Before buying a camera for video, check the crop factor in every recording mode you plan to use. A camera that shoots beautiful full-frame 4K at 24fps might crop to APS-C at 60fps and Super35 at 120fps.
