If you’re new to digital photography, you might well be wondering what all the fuss is about regarding the unveiling of full-frame mirrorless cameras. What’s the big deal about having a large sensor in a smallish camera? And what exactly does ‘full-frame’ mean anyway?
Most DSLRs and mirrorless cameras have an imaging sensor that’s the same size as a single frame of APS-C film – about 22 x 15mm. A full-frame camera, however, has a sensor with the same dimensions as a frame of 35mm film – 36 x 24mm. This means a full-frame sensor has more than 2.5 times the surface area of APS-C.
Why does size matter when it comes to sensors? Larger sensors can accommodate more pixels for more detailed pictures. For instance, the Canon EOS 5DS’s full-frame sensor houses around 50.6 million effective pixels, and can produce images that measure 8,688 x 5,792 pixels. That works out as a high-resolution 74 x 49cm print! With an abundance of pixels, it’s possible to make substantial crops to the full image in software to improve the composition, but still end up with a usable file size.
Not all of the best full-frame cameras outclass crop-sensor cameras in terms of resolving power, though. At 20.8MP, the Nikon D5 has almost the same pixel count as the company’s 20.9MP Nikon 500 flagship APS-C SLR. This means that despite the difference in sensor size, both cameras are capable of producing an image that’s the same size.
Common sensor sizes
There are a wide range of sensor sizes, from the smaller chip in camera phones to the 150MP medium-format monster in the Phase One XF IQ4. But three formats dominate in DSLRs and mirrorless cameras...
Full-frame and crop-sensor cameras – what's the difference?
The big difference between full-frame cameras and crop-sensor cameras that share a similar resolution in this vein is the size of the pixels. The pixels on the full-frame sensor are larger, and this allows for more efficient light gathering. The upshot is cleaner, better-quality images at high ISO settings, which makes a difference when you’re shooting in low light or at night, or when you’ve increased the ISO sensitivity to get a faster, action-stopping shutter speed.
There are further technical and creative reasons why you might consider making the move up to a full-frame camera. For a start, it’s easier to exploit shallow depth of field effects, so that images have more blur and less sharpness. The effect is enhanced when a large-aperture full-frame prime lens is used.
Shallow depth of field contributes to the appealing full-frame aesthetic – something exploited by filmmakers keen to get the cinematic ‘look’, as well as photographers – although it is entirely possible as well to reduce the depth of field when you use a crop-sensor camera.
Talking of lenses, you get more choice when it comes to full-frame. While other cameras are hardly short of options, there is a legacy of lenses from the days of film which is open to many full-frame users.
Something else to consider if you’re a cropped-sensor camera user looking at moving up to full-frame, is that your current lenses may not be compatible with a full-frame body, as the image projected by the lens won’t cover the larger surface area of the sensor – although some cameras get around this by switching to ‘crop’ mode. You can find out more about this by looking at what sensor is best for bird photography.
Crop-sensor cameras can deliver great images, so why bother with full-frame?
Although the design of components, image processing and lens quality make a big difference to the end result, a larger sensor allows for larger pixels – and more of them – giving a clean, detailed image.
Full-frame cameras are aimed at enthusiasts and professionals, so they tend to have the level of build quality that these users need. High-end crop-sensor cameras share a similar level of robustness.
You’re presented with a larger image in the viewfinder, which can make it easier to compose. It’s not always easier if you wear glasses, however: you may not be able to see the corners without moving your head.
The ability to crop full-frame images and retain image quality is a big benefit. Shots taken at high ISO settings can also be ‘downsampled’ – made smaller in software – to reduce the effects of noise.
Of course, full-frame isn’t for everyone. Despite the amazingly compact full-frame mirrorless cameras on the market now, full-frame bodies still tend to be bigger and more expensive. Check out the cheapest full-frame mirrorless cameras if you're on a budget, or consider buying a used camera.