Micro Four Thirds vs APSC vs Full Frame Depth of Field Comparison
The Internet is full of useful depth of field charts and tables. But sometimes a simple real-world comparison is all you want. In fact this is one of the most frequently asked questions which I receive in my mailbox each month. For the last few years I’ve been exclusively using Micro 4/3 cameras in both my professional and personal life. Then over the last year I introduced a couple of APS-C cameras (Sony a6300 and Canon 200D) and a full frame mirrorless camera (Sony A7rii). All have their own distinct uses.
As a full-time professional out in the real world, ultra-thin depth of field rarely raises its head in the vast majority of day-to-day situations. I’m talking about environmental portraiture, pet photography, landscape and street photography, and wildlife photography. If anything, the additional depth of field (and effective ‘reach’) afforded by the crop factor of the u43 sensor can be quite beneficial at times. When using a full frame camera I would need to stop down somewhat in the same conditions and use a larger and heavier lens. That doesn’t mean that my full frame camera is redundant, I keep it for those occasions when I need ultrahigh resolutions for extremely large print applications (a case in point being a billboard earlier in the year and occasional huge enlargements beyond about 40 inches). But what I like about this particular full frame body is that I can shoot in Super-35 mode which is hugely convenient at times.
The respective sensor sizes look something like this (with some slight variation according to your chosen aspect ratio). The Canon APS-C sensor (blue) has a ‘crop factor’ of x1.6 and the u4/3 sensor (yellow) is a little smaller at x2. The full frame sensor (pink) is notably larger than both:
The test target is the clothes airer in my back garden – one of my trees makes a convenient background reference point. I was shooting with the Pansonic GX8, Canon 200D, Sony A7rii. For the purpose of this example I shot each image at f5.6 (and the same aspect ratio) and I’ve framed in the same way for each photograph. I made sure that I stood on exactly the same marker for each picture – maintaining the same camera to subject distance means the background perspective remains constant. Incidentally ‘background blur’ is not the same as ‘bokeh’ which refers only to the characteristics of out of focus areas, particularly point highlights.
Even though the difference in size between a 4/3 sensor and a APSC sensor isn’t all that much, the depth of field difference in the photographs below is nevertheless apparent. The difference between APS-C and full frame is more obvious still. When shooting environmental portraits with my full frame camera, f5.6 is usually where I’m at when using a 70-200 lens at near to intermediate distances. On APS-C I’d be at about f4. The u43 lens lineup makes provision for f2.8 zooms. This gives me good subject separation and enough leeway for a small amount of movement. Very occasionally I’ll use my 85mm f1.8 lens on my A7rii at f2.8 for a controlled full length portrait – placing the focus point becomes ever more critical as depth of field shortens, but for moving subjects stopping down a little is key.