The most often claimed advantage of mirrorless systems is that they can be designed to be much smaller than DSLRs. While image processing and sensor technologies vary across DSLRs and mirrorless cameras, the fact that many mirrorless models use the same APS-C and full-frame sensors that you’ll find in DSLRs means that neither system has any inherent advantage when it comes to image quality. Indeed, this is the main sell of the system: the same size of sensor and image quality as offered by a DSLR without the bulk.
The Canon EOS M50, for example, has the same sensor and technology as Canon’s equivalent DSLRs but is a fraction of the size.
The main reason for this is that DSLRs have a mirror just behind the lens mount and an optical viewfinder mounted above it, whereas mirrorless cameras do not. On entry-level DSLRs with ‘pentamirror’ designs like the Nikon D3500, this doesn’t have a major effect on weight, but more advanced DSLRs with a glass prism in their viewfinder chamber are heavier.
There are often trade-offs in making a mirrorless camera body so compact, such as the size of the sensor and battery life, together with the way a camera handles with larger lenses, and how many external controls can be fitted.
Some mirrorless cameras fashioned like smaller versions of a DSLR while others have a smaller rectangular ‘rangefinder’ shape. These are often designed for novice camera users or smartphone upgraders more used to touch control than physical knobs and dials, so a simplified exterior won’t bother them. The Olympus PEN E-PL9 is typical of small mirrorless cameras designed for this new type of user.
Small bodies also means small controls, and users with larger hands may not find those on some mirrorless bodies to be comfortable. This extends to touchscreens too, with virtual buttons and controls often too small for then to be keyed comfortably, so although the Nikon D850 DSLR seems huge in comparison to full frame mirrorless camera, many of its pro users will prefer its size because it makes it much easier to see and change camera settings – and because it balances better with big lenses, which is what we cover in the next section.