I’ll be honest. I’m a bit tired of photography experts explaining how inferior ‘crop’ sensors are to full frame sensors for depth of field. By ‘crop sensor’ I mean APS-C and Micro Four Thirds.
These experts have a technical point, of course, in that full frame sensors offer shallower depth of field, better background blur and a more cinematic feel to video. That much is true, and there are good technical reasons for this. You get shallow depth of field from longer focal length lenses, amongst other factors, and full frame cameras use longer focal length lenses to get the same angles of view as shorter focal lengths on crop sensor cameras.
Again, I can’t argue with the theory. But I can argue with the assumption that we always want shallow depth of field. Sometimes it’s really useful, for isolating portrait subjects from their backgrounds, for example, or separating athletes from the crowds behind them. But often – very often, in my opinion – the shallow depth of field of a larger format can be a nuisance. It’s a nuisance for landscapes, for interiors, for close-ups and for any other kind of image where you want objects at different distances from the camera to all look adequately sharp.
I shoot with MFT cameras, full frame cameras and sometimes cameras in between, so I have plenty of opportunity to compare the pros and cons of each in everyday shooting. And what I would say is that I need the deeper depth of field of a smaller format camera far more often than I need the shallower depth of field of a larger format.
I’ll go further. With my MFT cameras I can shoot a wide range of subjects in varying types of light, indoors and out, without having to worry one half as much about depth of field. I use Olympus f/4 Pro lenses a lot and, even wide open at f/4 these offer a depth of field equivalent to f/8 on a full frame camera. If ever I’m out shooting with my EOS RP, however, or my Sony A7R II or Nikon D800, I’m constantly aware that there’s less depth of field and that I have to accept my subject being sharp and not much else. Either that, or really close down the aperture and take my chances with higher ISOs or slower shutter speeds.
Full frame cameras don’t permanently live in a world of dreamy bokeh and cinematic depth. Mostly, where sharpness falls away, it’s not dreamy at all, but a slow and insidiuous softening of detail away from the point of sharp focus that can make full frame images look less sharp overall than those taken on a smaller format.
You can argue quite rightly that it’s a matter of photographic skill to get these things right. And so it is – if there’s time to work through the best aperture and focus distance, and there’s enough light to use a small enough aperture to get the depth of field you want. The larger the format, however, the harder you’ll need to work at it. You’re playing catch-up with smaller formats that are innately better at the thing you are trying to achieve.