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Square sensors for mirrorfree cameras (by Zoltán Biró).


This is a guest post from Zoltán Biró. Feel free to contact me at if you want to publish an article on 43rumors!

Square sensors for mirrorfree cameras (by Zoltán Biró).

Once imaging technologies have evolved, some interesting projects become achievable far more easily than before. That’s the case with the square-shaped multi-orientation and multi-aspect ratio sensor, which would pose a real problem for DSLR technology but are quite easy to implement for mirrorfree cameras.

What is the square-shaped multi-orientation and multi aspect ratio sensor (SMOAR)?

The SMOAR is a square sensor which – unlike e.g. some medium-format cameras – should cover not just the image circle for 1:1 (square) format but also for 4:3 portrait, 4:3 landscape, 16:9 portrait and 16:9 landscape modes respectively. See the illustration below (the 4:3 modes are omitted for simplicity, they have to fall anyway between 16:9 and 1:1). Somewhat similar to ‘conventional’ multi-aspect ratio sensors – and opposite to classical square formats – there is no mode where all the pixels from the whole sensor would be used simultaneously.

What would be the main benefit of such sensors?

This type of sensor renders the portrait grip and camera rotation obsolete: you can always hold the camera in its ‘natural’ (landscape) position even if you want to shot in portrait mode. The orientation could be set (together with the aspect ratio) using a button or switch – instead of rotating the camera body.

Advantages (beside the main benefit):

  1. A simple tilting screen/viewfinder would be enough for all situations, no need for the swivelling screen.
  2. Using a tripod is much easier as there is no need for a special head which lets the camera be used in portrait mode. Moreover, the camera always stays centred on the tripod, its centre of mass would fall much closer to the tripod axis for enhanced stability. Also much more convenient for shooting mixed portrait/landscape from tripod.
  3. This is even more evident when using a monopod in which case shooting with rotated camera is a real challenge.
  4. True (not cropped) 1:1 aspect ratio would become available for high resolution square photos.
  5. When shooting in RAW you can even decide lately whether you want to use portrait, landscape or square crop.
  6. No need of orientation sensor.
  7. No need of rotating on-screen information for a better readability.
  8. No need to ‘learn’ a much less comfortable layout when keeping the camera rotated (besides the normal position where the controls are already optimised for maximum comfort).


  1. Obviously, the sensor has to be bigger, which means less space for additional circuitry, more heat dissipation, bigger cost etc. However, the sensor size won’t exceed even the (Sony) APS-C sensor surface.
  2. Manufacturers would either accept that the viewfinder/screen image has to be smaller when shooting portraits or should implement square EVF/LCD. Although a square viewfinder may be a bit more pricy, a square rear screen would be even more convenient as it allows more space for additional buttons.
  3. The mechanical shutter has to be also bigger which would be the only serious drawback (GM1 can be such small because of its hybrid shutter, even a pure mechanical 4:3 shutter wouldn’t fit in the body). The size remains an issue only until mirrorless shutters become exclusively electronic ones (what I hope will happen very soon).
  4. Some lens hoods are asymmetrical and optimised for landscape use. This is a real problem, but fortunately this is mostly the case of wide angle lenses where portrait shooting is hardly typical anyway.
  5. The sensor readout time might be increased (but likely just for RAW shooting if the reading is made already optimised for the appropriate jpeg orientation).


  1. The body should be bigger to house the bigger sensor. False, as the sensor would fit anyway behind the (much larger) mount assembly.
  2. The electrical contacts of the mount may obtrude and obscure the sensor. False, as they are placed way outside the image circle.
  3. Lenses are more or less optically designed to be used in landscape mode. False, all but a few cine- lenses have circular symmetry alongside the main axis.

Why this sensor would be much easier to implement with mirrorless systems than for DSLRs?

The flange distance should be increased due to the fact that the mirror assembly (mirror, pentaprism) should be also bigger, this would be unacceptable for existing DSLR mounts. Fortunately this problem is actually no problem for mirrorless systems.

If this sensor is such good idea why manufacturers have not implemented it already?

This is mainly because of conservatism. Just take a look e.g. on the lack of success of mirrorless systems despite of their long-confirmed viability. The other reason may be the problem of the mechanical shutter which – at least as I hope – will become history within a few years.

So, dear colleagues, what do you think, is this proposal worth to be focused on by Panasonic or Olympus – at least for premium models, where the size or the cost factor are not so critical?

Would you like to get a square sensor MFT camera?

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