The announcement of the Nikon Zf seems to have rekindled an old adage: full frame is better than APS-C. Some are saying that full frame cameras have the minimum sensor size necessary for serious photography, and APS-C and smaller are for amateurs. But is this actually true? Is full frame superior to APS-C? Can APS-C cameras be just as good or perhaps even better than full frame? Does the size of the sensor actually matter all that much? Why even buy a Fujifilm APS-C camera now that Nikon has the full frame Zf?
At the core is the physical size of the sensor. Full-frame is 50% larger than (most) APS-C. The size of a full frame sensor is the same as a 35mm film frame, while the size of an APS-C sensor is the same as an Advanced Photo System Classic film frame. In the film days, no respectable pro or enthusiast photographer used Advanced Photo System cameras. Why should they in the digital age?
Back in the early days of digital, when dynamic range and noise control were much more critical than nowadays, full frame had a clear advantage, as one needed to squeeze the absolute most out of their files and full frame allowed that. APS-C was more affordable and smaller, so it was popular with amateurs and enthusiasts on a budget. This is where the stigma originated that APS-C is not for those who are serious, and to an extent it unfortunately remains to this day, despite so many incredibly talented and successful photographers utilizing APS-C models.
Since APS-C sensors are smaller than full frame, there is less physical room for light sensitive sensor elements (pixels). There are two options: smaller pixels or fewer pixels. Smaller pixels will allow for increased resolution, but at the expense of low-light capabilities and dynamic range. Fewer pixels allows for better low-light capabilities and dynamic range, but at the expense of resolution. Resolution is resolution, and 24mp on full frame is the same as 24mp on APS-C, yet the pixels on the APS-C will be smaller than those on the full frame sensor. 61mp on full frame is more resolution than 40mp on APS-C, yet their pixels are similarly sized. It’s easy to see the advantage of full frame! Except that most photographers don’t actually need 40mp of resolution, let alone 61mp. It looks good on paper, and it’s great for pixel-peeping and bragging rights, but in practical use, the majority of photographers don’t actually need more than 20mp, and everything above that is overkill. Yes, there are some who do need more, because they crop deeply or print huge, but most people who say they need that much resolution don’t actually need it. Megapixels sell cameras, though, so camera makers keep pushing higher and higher. My argument is simply that there is plenty of real estate on an APS-C sensor; while the increased room on full-frame sensors does offer advantages, those advantages find themselves on a diminishing returns segment of an inverted U curve.
Improved dynamic range and high-ISO are often overstated on full frame. The dynamic range of, say, the APS-C Fujifilm X-T5 and the full frame Canon EOS 5DS R are quite similar, and not much different at all in real world use. There are some APS-C cameras with more dynamic range and some with less dynamic range than the X-T5; likewise, there are some full frame cameras with more dynamic range and some with less dynamic range than the 5DS R. But even if we’re talking about an APS-C camera with less and a full frame with more, in practical use, that difference is fairly insignificant (outside of some extreme circumstances). Same with digital noise. Full frame might be cleaner with less noise—particularly as the ISO climbs—but a camera like the X-T5 has a film-grain-like rendering to the digital noise that is much more tolerable than the noise from the 5DS R. In other words, the more noisy X-T5 might be preferable to the less noisy 5DS R at the same ISO. For the most part, full frame does have the advantage with both dynamic range and high-ISO, but it isn’t nearly as big nowadays as many might think.
Now let’s talk crop factor, which is often given as a reason to choose full frame. Because full frame sensors are 50% larger than APS-C, there is a 1.5x crop factor for APS-C focal lengths. For example, a 50mm lens on an APS-C camera will have the same focal length as a 75mm lens on a full frame camera. If you are trying to reach far, it’s a little easier on APS-C than full frame, and if you are trying to go wide, it’s a little easier on full frame than APS-C; however, there are plenty of long telephoto and ultra-wide lens options for both sensor sizes. Crop factor also affects depth-of-field, as f/2 on APS-C has a larger depth-of-field than an f/2 on full frame. If you want a shallow depth-of-field, it’s a little easier to achieve on full frame than APS-C, but if you want a large depth-of-field, it’s a little easier to achieve on APS-C than full-frame; however, it’s still very much possible to get a small depth-of-field on APS-C and a large depth-of-field on full frame. One often-overlooked advantage of APS-C is that, to achieve that shallow depth-of-field, you’re likely to use a larger aperture, allowing more light to reach the sensor, which means shooting at a lower ISO.
Perhaps the biggest advantages that APS-C has over full frame—and likely the main reasons why most choose APS-C instead of full frame—are size and price. APS-C cameras are often smaller and weigh less than full frame. Smaller gear can be preferable, especially when traveling, and it can potentially provide a better user experience. Because the sensor is smaller, the price is often lower, sometimes much lower. Your money often goes further with an APS-C system than full frame.
While APS-C cameras can have some advantages over full frame, and some of the strengths of full frame can be overstated, bigger sensors obviously do allow for more and/or bigger light sensitive sensor elements, which generally speaking is better. My point is not to diminish full frame, because they serve important purposes, and can be preferable; instead, my point is only that the stigma that APS-C is “less than” and isn’t for serious photographers is outdated and inaccurate. Full frame has advantages, and APS-C has advantages, and you might find one more preferable than the other, but they are both very capable sensor sizes. My personal preference is Fujifilm X-Trans APS-C, as it works quite well for my photography. You have to decide for yourself what works best for you. I just hope that the stigma can finally be put to rest, as it’s simply not true.
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