I recently found myself contemplating the thorny issue of APS-C vs full-frame sensors. You see, I’m wondering whether my next camera body should be the new Fujifilm X-T3 or the Nikon Z 6.

Oh, to be on the horns of such a sweet dilemma, I hear you cry. No? Moving on.

I have lenses for both systems. So why spend nearly double the money on a full-frame camera? Which, in the case of the Nikon, I will need to use with the F-mount lens adapter for the foreseeable future.

The smartphone camera that’s as good as a DSLR – apparently

We’ve all read all those articles that claim the latest smartphone cameras can take photos that are every bit as good as a professional DSLR takes, with side-by-side image samples to prove it. Can we assume from this that the professional photographic community are throwing their camera kits into the non-recycle bin and taking to their beds with bottles of colourless hard liquor? Probably not.

If a smartphone, with its pathetic little sensor, can take photos that are equally as good as a DSLR, then why bother with a dedicated camera? And who cares if it has a full-frame or an APS-C sensor?

The great, big, light-guzzling sensor on a full-frame camera and the titchy little sensor on a smartphone have something in common: They are both composed of individual photosites (or pixels) using similar technology. Each photosite, regardless of what sensor it is built into, has, give or take, the same functionality. The photosites on the smaller sensor are necessarily smaller, otherwise they wouldn’t all fit on to the surface of the sensor. (You see. I do know my stuff.) So here is the first thing that needs to be addressed – the smaller the photosite, the worse the signal to noise ratio. That’s physics for you, so there’s no point in getting antsy with me.

Physics is what it is

In fact, physics is the absolute arbiter of this argument. If you want to get the same amount of accurate image data from a small sensor/lens combo as you do from a large one, the only possible way this can be achieved is by taking longer exposures or multiple exposures.

Smartphones do indeed use all sorts of multiple exposure and mathematical tricks to get around this degraded signal problem, which requires extra image capture and processing time. This plays to a smartphone’s strength because it may well have a more powerful CPU than your average high-end camera.

Given ideal circumstances for its image sensor, a smartphone can, with difficulty, be coaxed to produce an image that is equally as competent as a DSLR. The limitations of these ideal circumstances quickly becomes apparent in practice. While it’s true that smartphones have exceeded our expectations in producing usable snaps of our lives, making a Hollywood feature film or a Vogue magazine feature photo-shoot with one falls unequivocally into the tray marked ‘gimmicks’.

About APS-C vs Full-Frame

So back to the APS-C versus full-frame argument: A decent APS-C sensor is, absolutely, capable of producing images almost indistinguishable from a full-frame sensor. As long as you don’t look too hard. Which is to say, as long as you don’t go blowing it up too much or doing too much post-processing and go spoiling the illusion by exposing all that nasty hidden noise. Oh yes, and another thing – as long as you provide enough light.

To put this all another way, an optimum image from a small sensor may be as good as an average image from a larger sensor.

The big decision

So, is it to be the light and lithe Fujifilm X-T3 with its APS-C sensor and its too-good-to-be-true good looks, or is it that dark horse, the full-frame Nikon Z 6 with its top-of-the-line Nikon hand-feel? (What, no Canon? Or Sony? I’m convinced that they produce great cameras, but I have never gone that direction.)

Both these cameras are capable of producing fantastic images, so it’s not about IQ. And anyway, I’m just as likely to put up with a less than perfect lens if it is nice and small and easy to carry. But the thing about the more expensive full-frame camera is that it can operate better with less light. Not only that, it has IBIS. Put those two things together and you have an image capturing monster that can get a half-decent image anywhere short of a coal mine with the lights out.

Whether it’s in a poorly lit church, a concert arena, a field of combat or just challenging lighting on your average, every-day, travel photography jaunt, the Nikon is more reliably capable of grabbing an image just the way you saw it. Is that worth the extra bucks? I think it is.

The final word – Finally!

So here is the advertised final word – at least – the final word as of the beginning of 2019, so it’s probably good for a couple of years.

Is an APS-C sensor as good as a full-frame sensor? Yes, near enough – as long as you accept its comparative light-capturing limitations and that the image noise will begin to show up more quickly as you enlarge it, or process it for that matter. If you’re good with those two caveats then don’t waste your money on a full-frame banger. For that matter, stick with your smartphone if that covers the majority of your photographic circumstances, because, of course, that’s what this all boils down to.