The Exposure Triangle – A must know!

31 May

The Exposure Triangle is important to know like the back of your hand especially in regards to HDSLR  film-making where as the slightest change in sunlight can completely throw out your image. If like me you studied at University its likely you got into your THIRD year before lecturers even started going into this in detail, personally I find that to be a joke. Lucky enough for me my passion for film and the vast amount of online resources meant I learnt this a while ago, but if it wasnt for my intern and venture into HDSLR films I probably wouldn’t have. Anyway, this is a PHOTOGRAPHIC technique that you must know and understand so please read it, it WILL change how you Film forever.

The Exposure triangle is based on three methods of controlling your cameras image – ISO, SHUTTER SPEED, APERTURE which combined create a perfectly exposed picture.

  • ISO – the measure of a digital camera sensor’s SENSITIVITY to the light.
  • Aperture – the size of the opening inside the lens when a picture is taken, essentially how much light is lets in. This is the QUANTITY of light that is hitting the sensor.
  • Shutter Speed – the amount of time that the shutter is open per second, i.e 100/1sec, the will shutter open and close at a hundredth of a second. This is the DURATION of how long the light hits the sensor for.

ISO is what the 5Dmrkii & iii are best known for, these cameras can shoot an incredible high ISO with very little noise. Here’s what I mean by noise, as a rule of thumb the lower your ISO the lower the Noise. Remember when shooting for film use 1/3rd increments for your ISO settings so, 320, 640 e.t.c :

LOW ISO – 100    HIGH ISO- 12,800

NEVER use and kind of auto settings on your HDSLR camera, NEVER!. You must do everything yourself manually other wise your settings will be constantly changing whilst you are actually filming, resulting in your video visibly changing settings. The same goes for white balance, LOCK YOUR WHITE BALANCE DOWN and don’t change it until you either stop recording or you move to a different location with different lighting. Back to the Exposure triangle.

Aperture is the iris inside your lens that controls the AMOUNT of light coming into your cameras sensor. Whether its all the way closed only letting a tiny amount of light in (Aperture f22), or very slightly closed letting tonnes of light in (Aperture f1.2). Note the wider you have your Aperture (wider/wide  open would be a small Aperture of f.1.2 or see below f2.8 letting tonnes of light in) the Narrower your DOF. See images below.

Last but not least we have SHUTTER SPEED. As mention before this is how fast the shutter closes per second. By using shutter speed you can create some very interesting effects however, In film you LOCK DOWN your shutter speed to TWICE that of your frames per second. For example 25fps (PAL) would be a shutter speed of 50th/1sec and so on. This is to create enough motion blur in each captured image that the Human eye can see the images blend smoothly together. If you use a higher shutter speed for this you will get a stuttered still motion effect, (sometimes these high shutter speeds are needed, i.e creating slow motion). For PHOTOGRAPHY you can change the shutter speed to whatever you like, just remember to change it back to 50th/1 sec when you want to start filming again.

Here’s some popular PHOTOGRAPHY effects using different shutter speeds:

So there’s the basics behind the Exposure triangle. By combining all three together you get that perfectly exposed image. Try it for your self, don’t rely on any auto setting’s, set your top dial to M for manual and play around. Try shooting an image with very Narrow DOF, (where a large potion of the image with be out of focus and the object you wish to draw attention to will be in focus) and an image with very Deep DOF (where everything is in focus, i.e a landscape image.


  • Shoot as wide open as you can or place your subject closer to the camera. 
  • Having a wider Aperture for narrower Depth of Field will result in you using a much lower ISO, thus you will get a much cleaner images (less NOISE).
  • In an outdoor situation Narrow DOF is much harder to create because you are being bombarded by tonnes of Daylight, mostly resulting in ‘Stopping Down’ (closing you aperture to let in less light). Instead Invest in a Variable ND filter to block the light first, resulting in you being able to open up your Aperture.
  • Dont over do the narrow DOF technique, for an interview scene f1.2 is TOO NARROW, use it respectively people don’t want to see someones nose going in and out of focus. This technique can look amazing so think about how you can use it to make your film look more like Cinema.

I hope this Post has been useful, check out this video if you can’t be arsed reading. Remember DO NOT USE AUTO SETTINGS, keep everything manual:


One Response to “The Exposure Triangle – A must know!”


  1. Datavision I-pad prompter « - January 2, 2013

    […] One quick thing to remember is that the traditional mount option reduces the amount of light entering the camera by up to 2 stops. […]

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