Exposure Triangle? Could anything be more confusing?!

I admit I am a very lazy photographer.  I often say that I don’t care what settings my camera is on…. I don’t want to be bothered by technicalities… I’m an artist……
So most of my pictures are taken on auto, and they turn out fine, but every now and then I am dissatisfied with a picture and my husband (who is geeky and understands all things camera) tells me (annoyingly) that the picture would have been better if I had understood the settings.
I am about to undertake an important assignment, one I am very excited about and one I do not want to mess up, so this weekend, I reluctantly realised that I needed to knuckle down, stop being so stubborn, and get to grips with using my camera in manual control.
And that means understanding this “exposure triangle” thing.
I’ve always individually ‘got’ the three aspects of the triangle, on their own they make sense, but the terminology is designed to be confusing (I swear!), the numbering system is crazy and each explanation uses a variety of terms to describe the same thing.   It’s all very counterintuitive.
I printed out a picture of the exposure triangle (if you Google it, there are many to choose from) and set to work understanding it.
After reading three explanations I had covered the diagram with extra annotations, and slowly but surely a clearer picture emerged for me.
I had a “Eureka!” moment when I realised that I had been looking at this all wrong, the answer was in fact simple!   I suddenly saw that there are three settings, you decide which one is fixed (basically, are you looking for depth of field (Y?N?), quality (Y?N?) or motion blur (Y?N?) – at this stage of my understanding,  I am pretty sure you can only have one main one that you’re concentrating on, the others have to compensate….) and then the other two need to be adjusted like a seesaw with a fixed fulcrum.   Simples.

The exposure seesaw – fix one and adjust the other two to adapt to conditions

So, just in case there are any other confused photographers out there I have made some notes and a couple of new diagrams to add to the genre to see if that helps anyone else too.


  • Also known as ‘lens opening’ it affects depth of field.
  • Terms around it include ‘bokeh’ (technically the quality of the out of focus bit), background blur, fStop.
  • Measured in fStops which are fractions but written f/5.6 (think 1/5.6 instead)
  • A narrow aperture lets in less light, there will be less background blur, less bokeh this means MORE depth of field, more in focus.
  • A wide aperture lets in more light, there is more background blur, more bokeh, and LESS depth of field, less is in focus.


Exposure Time

  • Aka shutter speed, time value (Tv).    This is used to control motion blur.
  • The longer the shutter is open, the more light gets in, and the more motion blur you’ll get.   After a certain point, you’ll need a tripod because your shaking hands will cause motion blur on the picture.
  • A faster (high) shutter speed, has less light, this will freeze motion (sport, cars, water etc) and can be done by hand.
  • A slower (low) shutter speed lets in more light, this allows for motion blur but as a rule of thumb will need a tripod roughly over 1/60 (one sixtieth of a second) – [telephotos are different again].   Some cameras have image stabilisation which means you might be able to hand-hold for longer exposure times.



  • Aka ‘ISO’ or image quality, how much noise or grainy the image will have.
  • A low ISO (for instance 100) is the least sensitive and good for bright conditions, or when you want the highest quality (least grainy) image.
  • A high ISO (such as 12,600) is the most sensitive, and is equivalent to letting in more light but will result in the lowest quality, quite a grainy poor image.



The three factors above are measured in ‘stops’ – a sort of standard measurement scale, each twice as big / small as the last – which are comparable in as much as moving one element up or down a stop or two should be compensated by reducing another measure by a similar number of stops (roughly).
Eg the aperture scale contains: f/2.8, f/4, f/5.6, f/8 etc. [It makes no apparent sense that the actual numbers are not twice as big as the last, but it’s about the light they let in].
The shutter speed scale is similarly:  1/250th, 1/125th, 1/60th‘s of a second and so on, – again each stop one lets in twice as much light as the one before.
Cameras differ and will often allow users to set settings in between the standard stops I’ve mentioned.
Therefore, if leaving ISO fixed, if the aperture is increased by two stops, the shutter speed can be reduced by two stops and this will help control depth of field or motion blur as required.
Or looking at my see-saw diagram below, if I want lots of bokeh, (a shallow depth of field) I set that on the camera, eg f/4.   This lets in more light so I will have to reduce the ISO and / or increase the shutter speed to control the light.   Each of those will depend on the conditions, are you handheld?, what quality you want etc.


This is a very basic guide, which I wrote for myself to get to grips with the subject, but I hope that someone else who was equally confused might find some light being shone on the topic 🙂
I was going to call this an ‘idiots guide’ or ‘dummies guide’ but I am neither an idiot or a dummy I was just very very confused about all the terminology and nonsensical numbering system.   I am sure there must be others out there, equally perplexed!


Two of the sites I used are:


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