Photo Lesson 7: Feeding the meter

I’m filling in my time between trips by thinking about what makes a good holiday photo, and the first step towards the perfect shot is understanding how images are created, and knowing your camera.   When you take the perfect picture your heart races a little every time you view it.  So, stick with me and I’ll help you get there.

Now, last post we looked at exposure, but didn’t elaborate on how the camera calculates the correct exposure for your scene.  Let’s rectify that oversight now.

Find your hidden meter
Every camera has some sort of light meter that it relies on to detect the quantity of light and, using the calculation we have discussed previously, selects the best aperture and shutter speed for the shot.

We don’t really need the technicalities of the inner workings of light meters in order to take advantage of them.  But we do need a camera that allows you some interaction with it.

This interaction starts, and the magic begins, when you start to press the shutter release button.   On all the digital cameras I have every owned, compact, bridge or DSLR, and many film cameras too, shutter buttons work in two stages – the half press, and the full press.

Related image

When you press the shutter release button, which you should do by squeezing the button with a gentle steady pressure from your finger, you should feel a slight resistance when the button reaches the halfway mark. On most cameras, the following will happen:

  1. If the camera has been in standby, it will wake up.
  2. The camera’s autofocus system ( if it has one) will check and adjust the focus
  3. The camera will switch on the metering, and set a shutter speed and aperture

You will normally know when the focus and metering operations have completed from the viewfinder or back screen.  There is normally an icon in the middle of your screen that will change colour (commonly red or yellow to green), or size or shape, to let you know that the camera’s exposure and focus are set and you are good to go.   You might even get a beep!
Image result for d3200 focus indicator
At this stage, squeezing the button further until it reaches the full travel will cause the camera to trigger the shutter and take the image.

Taking control
Normally, as you move the camera around, the meter will keep adjusting the exposure settings for the light that it is seeing through the lens.  One trick that can be very helpful, if your camera supports it (and most do) is exposure lock.    Sometimes this is done from the shutter button, or sometimes there is another button that you hold down with another finger, so check your camera, but how this works is you point your camera towards the part of your picture that you need to be correctly exposed (e.g. someone’s face) press down the shutter button to halfway, and then no matter how you adjust your composition including point the camera up at the sky, or into  dark forest, the exposure will be remain correct for the face, whileever you hold the button down to lock exposure..   You can experiment with this.  Try going outside on a sunny day, and find somewhere with a lot of shadow.   Point the camera to the sky and take a shot, and odds are the shadows will be black.  Now take another shot, but point the camera into the shadows first, and then hold down the shutter button (and AE Lock button if necessary) then move the camera back to the original position while holding the button down halfway and take the same shot again.  If the lock has worked, you should find more detail in the shadow, and the sky more burnt out as it will be over exposed.

Manipulating the meter
Something that will help with the above is changing the way the camera takes the meter reading.   Some basic compacts won’t have this function available, because being basic, you are suppose to let the camera handle everything.

But better compacts, bridge cameras and DSLR’s have a meter mode setting:

They work in different ways and I suggest you check your camera’s instruction manual, but commonly you will find:

  • Average (or matrix) metering : The camera measures the light in all portions of the image, including the highlights and shadows, and comes up with an average setting.  This is the default setting and is fine most of the time and works best for evenly lit subjects.
  • Centre weighted – Like average average, but gives more bias to the centre of the camera, as normally that’s where your subject will be framed.  If your subject is mainly always in the centre of your frame, this might be a better choice of meter mode, as it ignores highlights and shadows on the edges of your frame, which aren’t important to the shot but will affect the exposure setting in average mode.
  • Spot metering – In spot mode, the camera only takes the meter reading from the area normally within the focus brackets (although on some cameras you can re-position the “spot” within the frame, where the reading is taken.  By pointing the “spot” at the portion that you need correctly exposed, you can ensure that the camera’s settings are correct for your target subject. This is ideal for badly lit subjects or subjects with extreme contrast.

You might have guessed that spot mode works really well with the exposure lock, if the area you need exposing correctly isn’t in the centre of your image.  Simply select spot mode, point the camera at the target, lock the exposure, and then re-compose your shot!

Think exposure
There is nothing worse than taking a photo only to find the exposure was wrong afterwards.   Correct exposure is a fairly basic requisite for the perfect shot, and you should now be armed with the information you need to take control of the exposure.   but this information isn’t any good if you don’t consider it when taking a photo.  So, next time before you push the button, look around at what you are taking, and decide if the default settings are going to work for you.   Better still, review your shot straight after you have taken it, and if the exposure is wrong, delete it, change your settings and take it again!

Your decision this time is this – do you want to allow the camera to do all the exposure work, or do you want to have some control?  If you are happy to let the camera deal with exposure, then the basic compact is ideal for you.  But if you want to have a say in how exposure is calculated, then you need a compact with exposure settings, or maybe you should be looking at bridge and DSLR cameras…

To be continued…

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