The great lie.
September 24, 2025This one’s a bit of inside baseball. IYKYK, so to speak.
I’m getting sick of hearing about all these mythical so-called “full-frame” digital sensor cameras. For anyone not in the know, the term refers to a standard size of sensor based on 135 film. We used to call that 35mm, based on the diagonal measurement of the frame, 36mm wide by 24mm high. It’s been some time since I had to use any of my high-school math, but if you know the formula for calculating diagonals, (the constant β figures in there somewhere), you can see how that number came to be.
So plenty of cameras these days use that 35mm frame as their sensor size. And plenty of others use smaller ones. The smaller ones tend to have various designations decided on by camera manufacturers’ marketing departments: APS-C and APS-H, four-thirds, micro four-thirds, 1-inch, 2/3”, etc. You can google it to see how they compare. Note how none of these sensor sizes are described according to the actual physical sensor dimensions . Like much of what marketing departments come up with, that obfuscation is by design.
35mm isn’t the largest frame size. In the world of film it’s rather lilliputian. Even among digital sensors, it’s not the largest. I own two digital cameras, one of which contains one of the largest digital sensors you can purchase as a civilian. The other has a 35mm sensor. Both are great cameras, both do things that the other can’t, and they both continue to bring me joy when I use them. But the idea that the 35mm sensor is a “full” frame – that it’s the largest there could possibly be – is patently and demonstrably ridiculous.
So where did this notion of a 35mm frame being “full” even come from, you might ask. The answer to that hearkens back to those very same camera marketing departments, back at the turn of the 21st century, when digital cameras were just beginning to appear in the market. Among early digital single-lens reflex cameras, most (though not all) used sub-35mm sensors, but they were built to use lenses designed for 35mm film cameras, since a good many photographers already had those lenses at hand. Those lenses were made to project an image circle large enough to cover a 35mm frame (with a little to spare, to account for any vignetting at the edges). Since these newfangled digital sensors were only using a small portion of the projected image, they were designated “crop” sensors. It would be a number of years before camera manufacturers began making lenses designed to create smaller projected image circles to specifically fit these “crop” sensors. And was a few years longer before they built cameras with larger sensors that could fully take advantage of the old lenses – 35mm sensors, in other words.
Marketing departments being what they are, they decided they needed a way to differentiate between sensor sizes in cameras. They already had “crop” sensors. They needed to create another term to describe the 35mm-sized sensor cameras. A term that could instill a bit of FOMO. Thus, “full-frame”, with all its associations of superiority and professionalism. Not to mention the professional price tag: early 35mm DSLRs weren’t cheap.
So why do I hate the term? For the same reason I hate “professional photographer” – it’s pretentious as fuck. It’s also silly in implying that there can’t possibly be any larger sensor size. I should know, after all.
Frankly, the term is stupid, and for the sake of clarity and honesty, the photography world really needs to ditch it.