Digital formats have often ended up mimicking the dimensions of film formats, simply because the lenses for those formats already existed. But the higher performance and more steeply rising cost of fabricating ever larger expanses of silicon mean that the image quality gains from slavishly matching film formats becomes uneconomic beyond a certain point. In short, the possible image-quality gain of a ‘6×9’ digital sensor simply isn’t worth the fabulous cost it would entail.

But this brings us to the sensor in the Phase One XF IQ4 150MP system, which measures an impressively large 54 x 40.5mm. This is a little over 2.5x the size of a ‘full-frame’ sensor and essentially matches the size of the 645 film format. It’s the largest digital sensor format in large-scale production and sits as the only practical option beyond the smaller 44 x 33mm medium format adopted by Ricoh, Fujifilm and Hasselblad.


Our test scene is designed to simulate a variety of textures, colors and detail types you’ll encounter in the real world. It also has two illumination modes to see the effect of different lighting conditions.

Based purely on size, the IQ4 150MP will receive 2.5x more total light (1.33 stops) with the same exposure settings than a full-frame sensor would. And, unlike previous generations of medium format cameras and backs that used rather outdated CCD chips, you need to consider very few caveats to this fact.

This is because the IQ4’s sensor is based on the same 3.76 μm pixels as those in the Sony a7R IV (and the Fujifilm’s GFX100 and recent APS-C models). This promises as much of an improvement over full-frame as full-frame does over APS-C, and twice the difference that exists between full-frame and 44 x 33mm.

This is, at the time of writing, the biggest version of a modern sensor you can go out and buy. Which is why we’re using it as our new reference-point camera. Explore our scene above and see what the larger sensor, and massive 150MP of single-shot resolution, get you.

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