Depth of field and other profundities

It is generally true that you need a proper tool for every job. Banal as it might sound, this maxim has a tendency to be misconstrued as one suggesting an expensive, “professional grade” contraption, which you will spend the rest of your life learning and paying for.

Quite often it is the opposite. A compact camera, such as the cult Ricoh GR or a cheap mobile phone (the above was taken with a Xiaomi Redmi that costs $120 a pop) may at times demonstrate an advantage over a mammoth full frame number even in versatility!

How so? We are used to thinking that large sensor cameras are a good thing. Less noise, higher ISOs, better colour gradations. All true. A mobile phone with a sensor hardly half an inch across is no match for those. Except one thing. A tiny sensor uses a very short-focus lens, a few millimetres for the normal angle of view. And lenses of this kind have a very large depth of field.

I remember a Thomas Heaton video on YouTube about photographing a seascape with a prominent foreground. He was using a special technique: focus stacking. The camera was, as it usually is with landscape shooters, installed on a tripod and it took two pictures, focusing in turns on the foreground and the background. Thomas then combined the shots in post-processing to achieve the edge-to-edge sharpness that he had needed for his landscape.

While the technique is a major pain, it is not even feasible if there is a slight breeze disturbing branches or foliage near the stitching line; you need a static scene. Also, your lens must have very low “focus breathing”, i.e. the scale of the image should not at all change as you refocus the lens or else the stitching software would have an awkward job of scaling and righting the distortion before combining the results. Ideally you need your optics to be good for video (where low focus breathing is a strict requirement) — and boy, do these trinkets cost!..

A mobile phone to the rescue. If you open the image above in a separate browser tab, you will be able to see it in full resolution. Including the leaf in the foreground, hardly a foot away from the lens, and the pebbledash church wall far ahead.

One shot — and all is sharp.

Your mobile phone is a valid tool. Even if you have a camera about your person, it sometimes pays to use the phone camera instead. Sometimes. Not all of the time. Do not leave your camera at home.

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