I was wading through HyperboleTube and came across a claim I hadn’t heard before: apparently we’ve all been lied too, having been told that we must use only ISO 100 … or else!
Hmm. That’s odd. Never heard that one before. It’s almost as stupid as the unfounded claim made by an infamous and allegedly professional photographer couple that ISO doesn’t matter.
Please tell me the majority of photographers in this world aren’t stupid enough to believe either claim!
Anyone who does has utterly failed to learn the underlying basic mechanics of photography.
Now personally I’m an old (very old) film-trained photographer and I like to use digital cameras as though they were film cameras. This means I tend to fix the ISO setting, usually at some standard film rating like 100 (as per the first claim). I have a couple of cameras that won’t go below 200 (which I often use even on the ones that do) and one that goes down to 80. There are not many times I’ve ever cranked it past 1600, except when experimenting.
So here’s the thing: ISO set too low means; 1). you may find yourself having to shoot at a large aperture and thus lose some depth of field sharpness; 2). the aperture needed may not be the best for sharpness; 3). you may find yourself having to slow down the shutter speed to where the image blurs even with stabilization; 4). you may not have enough light to get the shot at all. Whereas ISO set too high means; 1). you may need to use too small of an aperture to control the depth of field the way you want; 2). the aperture may not be the best for sharpness (which falls off in both directions from the optimum one for any given lens); 3). you may find the shutter speed ‘maxed out’; 4). you may have too much light to get the shot at all.
Okay, that’s the basics. The ol’ ISO/Aperture/Time business you probably already knew. Ergo ISO does matter, and only a moron thinks otherwise.
Now let’s look at the trickier aspect of it: how ISO relates to a particular camera.
First up, my almost dead Nikon P610. Great camera. Great lens. Tiny 1/2.3 16MP sensor. At ISO 400 the image noise is already noticeable. At 800 it becomes, for me, unbearable. Keep in mind that ‘noise’ is not the same as ‘grain’; an image can be grainy without being peppered with incorrect coloured dots in the field. Second up, my Canon T100. Great camera. Acceptable lenses from Canon, great if I stick an old manual Super Takumar on. Medium-sized APS-C 18MP sensor. It can manage ISO 800 without too much objectionable noise. Go above that and … not so good. Third, my Sony a6000. Great camera, aside from the tiny-size-accidental-button-pushing problem. Kit lens sucks, but I mostly use it with manual lenses anyway as it adapts them so easily. Again medium-sized APS-C 24MP sensor. This one can handle quite outrageously high ISO without the noise being a big problem. Why? Partly the pixels, but mostly a different sensor/processor/programming that handles the image information.
Three different cameras with three different abilities on ISO handling.
So, low ISO? High ISO? Let the camera choose? Which to use?
That depends on you; your shooting style, your camera, and the results you want/will accept. Just because I turn AWB off and fix ISO at 200 to shoot mostly telephoto images of wildlife in Program mode doesn’t mean you have to. Use P, A, T, or M as you see fit. Let the ISO and white balance go on automatic if you prefer. The reason why cameras have all these different setting is to get different results under the same conditions*.
Learn the rules, then learn when and how to ignore them. But don’t let any so-called ‘professionals’ tell you what you ‘must’ do, because that’s bovine fertilizer in a bag.
*I realize this is very close to the definition of insanity; repeating an action and expecting different results. But it is photography, after all, and it is an art form: some craziness is to be expected.