It’s pretty much accepted that the majority of images captured in 2020 happened after pushing a button on a mobile telephone. Did I just say button? Okay, we’ll let that one go for now.
Actually the number of images taken around the world in 2020 roughly equal the total number of images taken in the entire history of photography to the end of 2019, and most of those, as I say, were on mobile phones. That’s quite a thought. Over 150 years worth in one year. Actually, when you think about it for a minute, you’ll appreciate that that really isn’t that much of a surprise when you consider the processes required in the past to get your finished picture and the fact that all you have to do now is to pull your phone out of your pocket, much like drawing a Colt six-shooter from its holster, and shoot. And then hardly anybody does anything with the pictures. They just stay right there on the phone. So pressing a button 150 times when your grandad pressed a button once seems no great shakes at all.
Anyway, I digress, but only to a point. The cameras in phones are tiny. They make the diminutive spy cameras in WW2 look colossal when, at the time, these were regarded as miniature. In fact they were called sub-miniature.
But a tiny camera shoehorned into device just 5mm deep isn’t just a small version of a big one. Well actually it is in many ways, but it differs in certain aspects too. One of these is the way it handles perspective and depth of field. These two things can go hand in hand. To illustrate what I mean let’s switch to film cameras. This makes sense because the range of sizes in film cameras is so much greater than it is in the digital domain.
Before we look at film formats (sizes) we should take a look at lenses, but from only one point view. Their focal length. There are long ones and short ones, and there are many things to be considered before selecting a particular focal length, but let’s leave all of those to one side, for now … save for one. Depth of field. The depth of field of a lens is the distance between the nearest and farthest objects in a scene which remain in focus. The depth of field increases the smaller the aperture and the further away the objects are within the scene, but I wish to ignore these variables here.
The greater the focal length of a lens, the more its native depth of field reduces, in other words, the shallower it becomes.
Now let’s look at the big/small camera situation. The major reason for a lens change is to alter the perspective in the picture, so for the purposes of this piece we’ll keep it to a standard lens. The sort of thing that “came with” the camera you bought from the camera shop in the old days. The standard lens gives you not too much foreshortening and not too much compression, whatever not too much means! Loads of either might be just the job, but you’ll see what I mean in a minute. Anyway, the standard lens purports to be “just right,” like the three bears’ porridge. This focal length equates to the diagonal dimension of the film. So 35mm is 44mm, 120 (box brownie or Hasselblad) is 80mm, 6”x9” is 100mm, Quarter Plate is 135mm, 4”x5” is 160mm, Half Plate is 200mm, Full Plate is 270mm and 8”x10” is 325mm. Now how’s that for a big range of focal lengths? 44mm > 325mm and the perspective in the pictures taken with all these different camera/lens combinations will be exactly the same.
So what’s the point here? What’s different, apart from print quality of course? Well, remember the depth of field changing with the focal length? There it is. If you want the perspective within the picture to be the same but with a nice out of focus background as well, you need a bigger camera. Now you know why, if you’re using your iPhone SE (1st generation) with its dinky 4mm lens, you need to be practically on top of the subject to throw the background out of focus, even a little. And that lens isn’t even a standard one, it’s shorter (wider) … lots of foreshortening.
So the question seems to be, “does size really matter?”