Points in Focus Photography

Why You Shouldn’t Spend Time Memorizing the F-numbers


If you use the camera enough, you’ll end up memorizing them without doing anything at all

It’s often suggested that memorizing the aperture number sequence is something photographers should do. Unfortunately, the people proffering this never seem to be able to articulate why all that well. If it’s such a good idea, shouldn’t it be easy to point out how beneficial it is?

When someone tells me, I should do something; in a way, it’s a sales pitch. The product is the idea, in this case memorizing the f-numbers. The price is some of my free time. The payoff is whatever the benefits of doing the thing are.

I don’t think I’m alone when I say I have a limited amount free time; that makes my free time valuable. Therefore, I think it’s reasonable to expect someone presenting an idea to actually be able to convince me of its merit.

If you know the f-numbers you can adjust the exposure more quickly, for example, if you know f/5.6 allows twice as much light as f/8 you know you have to change your shutter speed from 1/60th to 1/30th.

Not very much of an argument is it?

Even worse, I’d say the way it’s presented is a bit disingenuous. Those full stops make everything nice and easy; substitute f/7.1 and f/3.2 and it’s not so easy anymore. Doing that also makes it apparent that you need to memorize more than just the whole stops which is often the only thing mentioned by the proponents.

Since what needs to be remembered is already snowballing, why stop there? Why not memorize the shutter and ISO speeds too?

Moreover, you don’t adjust exposure settings in a vacuum. You do it with a camera and cameras provide several solutions that involve no memorization at all. In fact, 3 technologies come to mind that have largely render memorizing f-numbers unnecessary.

  • Auto Exposure
  • The Meter
  • Click-stops at each setting

Even if we ignore the first two, you can easily keep the exposure the same by changing the shutter’s value by the same number of clicks as the aperture’s. In fact, coupled with the camera’s meter after a while it becomes so second nature you just do it.

However, I think the most damning reason not invest any time on this is simple; if you use the camera enough, you’ll end up memorizing them without doing anything at all. Off the top of my head, I can recite most apertures, shutter speeds and ISOs in 1/3-stop increment and I never actually spent a minute trying to memorize them. Just seeing them in the viewfinder enough times was all it took.

I’m willing to take this a step further, I don’t think think it’s necessary for most photographers to understand how the f-number is derived at all; there’s simply nothing intrinsically useful about it for most photography.

However, what is important is understanding how the aperture affects the image and that equal f-stops pass the same amount of light regardless of the focal length. The former, is important for controlling creative aspects of the image, in other words, depth of field. The latter tells us that if an exposure is 1/60th f/4 ISO 100, it will be the same regardless of whether the lens is 10mm or 1000mm.

My advice, if you want to spend time doing anything, practice handing your camera and changing lenses. Being able to change settings without thinking about where the controls are can have a massive positive impact on all of your photography simply by letting you get shots you otherwise would have missed. Being able to change lenses quickly can help keep dust off your sensor as well as keeping you shooting so you don’t miss the critical moments. Either way, there’s no substitute for familiarity and practice when handling your camera in the field.

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