WTF do all these camera settings do?

By someone who knows jack shit about photography and the artisic sensitivity of a dead pigeon, but I read the manual so you don’t have to.

If you want to take some photos, have a digital reflex or decent brige, and you think SLR means Self Loading Rifle , then you are probably in the right place.

So what do I care?

Well, if you have just spent 600 euros on an SLR and a lens because changing a lens on a camera is cool and makes you look a badass - but then only use auto mode is a bit of a shame as most good smartphones will give you excellent happy snaps already. The difference between camera vs smartphone is a bigger, more sensititive sensor that can get more light in darker situations, and all the settings that can really get you the photo you want rather than what your iPhone is able to take.

You can't take photos of a thunderstorm, or a starry night, or light painting with a smartphone. You can get ready in 10 seconds with a proper camera. I'm not going into how to do these, but from knowing what these options do, you can start to work out what you could do with your equipment.

What is a camera?

I'm going to science the shit out of this… A camera is a precision instrument designed to record a measured amount of light for a measured amount of time on a recording medium of a pre-defined de sensitivity to light.

I'm going to compare this by analogy with your eyes, as they more or less do the same thing.

So at it's most basic, a (digital) camera operates 3 mechanisms over which, depending on your camera, you may have more or less control:

  • The aperture: a sort of iris that lets in more or less light. Just as your eyes do in the dark or in bright light.
  • The shutter: A door that covers the sensor and opens for a certain amount of time to expose the sensor to the world. Like your eyelids.
  • The sensor, which you can set to be more or less sensitive to incoming light

Comparing to a human eye

  • Close your eyes, blink them open and close again, that was your shutter. How fast you blinked open was your shutter speed.
  • Your irises open in dark places, and close up in bright light, in an attempt to balance the sensitivity of your retinas to the ambiant light. That's your aperture.
  • Go from somewhere dark to light, or light to dark: Even if your irises can close down or open up almost instantly, your eye still needs a while to adapt to the overload of light or be able to adjust to the dark. That's your sensitivity. We cannot control that ourselves, but you can on a camera.

So, open the aperture, more light gets in. Good at night, but too much light during the day will wash out your photo, so you may want to reduce the amount of light when it's bright.

The shutter opens slower or faster, and allows the sensor to see more of a scene. Blink your eyes open and closed very fast and remember what you saw: Even if somthing was moving, you only saw it for an instant, as if it was fixed. That was a fast shutter speed. Blink slowly, and you will notice things moving. That's fine for our eyes that are more video more than still images, but transpose all that live movement into one still, will cause whatever was moving on the image to be fuzzy and blurred.

Finally, go from somewhere dark to somewhere bright. Your iris will close down instantly, but you will still be blinded, possibly with some discomfort for a few moments, while your brain gets used to seeing a lot of light: That's your eyes moving from high to low sensitivity. Go from somewhere light to dark, your irises will open right up, but you still won't be able to see details until your retinas clear up and restock chemicals needed to run the optic nerve in the dark: That's your eyes moving from low to high sensitivity.

Lets transpose that into camera.

The aperture is measured in f stops. The lower the number, the more light is let in. The shutter speed is measured in seconds. Or more often, fractions of a second, say in general for decent single lens reflex cameras, from 1/4000th's of a second to 30 seconds. The light sensor, fixed behind the aperture and behind the shutter, has a range of sensitivity settings, equivalent to silver oxide film sensitivity settings, measured in ISO numbers. The higher the number, the more sensitive to light the sensor will be

And so all the knobs and buttons help you adjust these settings - or let you select a preset value and the camera will manage these for you.

As an example of what “Automatic” takes out of your hands to help you, from my Canon 550D manual, the “quick start” guide has 8 illustrated steps on 2 pages that explain:

  • Charging a battery
  • Finding the battery and memory card slots and inserting the battery and memory card
  • Attaching a lens
  • Turning the camera on
  • Selecting “Automatic” on the program knob
  • Press the button to snap a photo
  • View that photo on the rear screen.

The remaining 256 pages go over all the other settings, features and menu options.

There are in general for an idiot amateur like me 2 other settings to know about:

  • White Balance: You can set the sensor to process light differently so that whites come out actually white and not yellow or blue. Sometimes the camera can guess right but can get confused, so you may need to explicitly set the white balance because:
    • Sunlight is white
    • Incandescent bulbs are yellower
    • LED bulbs and neon tubes are bluer.
  • EV +/- : - Exposure Value up or down. It allows you to bump up or down the exposition by forcing either the aperture or shutter speed depending on your program mode, allowing you to over or under expose a photo. This can be useful when taking a photo in a dark room with an outside window:
    • if your camera takes the window as a light source, you will be able to see everything through the window, but the room will be dark.
    • If your camera ignores the window, you will have a good shot of the room but the window will be blown out
    • If the camera is not taking the photo you expect, you can use this feature to crank up or down the exposure so you get the shot you actually wanted, overriding the camera.
    • Don't forget to set the EV back to zero when you are done to avoid surprises

Special shooting modes that can really help

Given that a digital camera sensor converts light to a digital signal, the camera’s brain box can process and enhance that signal. The camera maker has a notion of what is a “perfect” shot should be in specific conditions, and adds some quick access buttons to activate some presets from one easy switch. These are generally found on the program select dial on top of the camera.

So in addition to the manual and semi-manual options we have reviewed above, you may find some presets like:

  • Portrait : The camera will try to enhance skin and hair tones, possibly under artificial light.
  • Outdoors: The camera will try to enhance blue and greens for water and greenery, in sunlight.
  • Sport: Take fast non blurry shots of subjects in movement, and limit autofocus to the centre of the picture being taken and ignore everything else for a faster shot.
  • Night mode: Enhancing the sensor sensitivity, and changing aperture and shutter settings to attempt to give clear shots in darker environments - a tripod may still be needed or recommended!

Camera settings in a nutshell

Print these out and throw them in your camera bag!

The Holy Trinity of Camera Settings

The Aperture

Lets in more or less light to the sensor. Measured in f stops.

  • The difference between each stop doubles or halves the amount of light entering
  • Stopping down (going to lower numbers) opens up the aperture to let in more light.
  • Stopping up (going to higher numbers) closes the aperture down to let in less light.
  • The wider the aperture (lower f stop), the clearer the background is (wide depth of field)
  • The narrower the aperture (higher f stop), the more fuzzy the background is (shallow depth of field)

Shutter speed

The shutter controls how fast the sensor will be exposed to incoming light through the aperture.

  • Double the speed, halve the light. Halve the speed, double the light.
  • Slower shutter speeds will record more light - and also more movement, possibly leading to movement blur.
  • Faster shutter speeds will record less light, but also less movement, “freezing” a moving subject.

ISO sensitivity of the sensor

The sensor is rated in ISO numbers, as a carry over from classic photographic colour film.

  • The higher the ISO number, the higher the sensitivity
  • The lower the ISO number, the lower the sensitivity
  • Upping the ISO number can allow you to take better images in darker situations without having to resort to flash or longer exposure times
  • Digital sensors can run to very high sensitivity, but at the high range, for long exposures, such as night sky shots, the sensor can start to record “effects” that degrade the image quality.


Apart from the 3 main settings above that really influence how the camera can take images, there are some extra camera settings that can also influence the end result:

White Balance

Electronic sensors can be sensitive to different light “temperatures”, so you may need to manually set the type of light you are shooting under. Changing from sunlight to incandescent to fluorescent tubes can have a HUGE influence on your photo. If your photo looks blue or orange, set your white balance to match your light source if the auto setting is having a conniption fit.

EV - Exposure Value

If your photo settings are in the ballpark but a tad darker or lighter than you intend, you can fine tune your shot by adjusting the EV + or - settings, to over- or under-expose by a fraction. Remember to set them back.


Time exposures - or any shot longer than a tenth of a second will be blurry if you try to stabilise by hand. Use a tripod. They are cheap. Get one.

If you are doing long exposures on a tripod, when you manually press the trigger, you will jog the camera and get a blurry shot. Either use the time delay (so the camera will wait a few seconds before firing hands free) or use an external trigger. They are cheap too.


Try to avoid using the inbuilt flash where possible. They don't illuminate very far or diffuse well on the edges, and cast unnatural shadows.

For darker environments, open up the aperture, set a slower shutter speed, using a tripod if needed, setting a higher sensitivity can really transform a shot that auto mode would probably fire of the flash and look spooky.

Settings Reminder

Manual (M)

All aperture, shutter and ISO settings are available.

Aperture priority (A, Av...)

You set the aperture size and and the shutter speed is automatically managed by the camera - although you can influence the shutter speed slightly up or down via the Exposure Value settings. You have full control over the ISO sensitivity of the sensor.

Shutter priority (S, Tv...)

You set the shutter speed and the aperture size is automatically managed by the camera - although you can influence the aperture slightly up or down via the Exposure Value settings. You have full control over the ISO sensitivity of the sensor.

Programmed Automatic Exposure (P)

The aperture is automatically managed by the camera, but can be manually adjusted, and the camera automatically adjusts the shutter speed accordingly. ISO sensitivity can be adjusted, and Exposure Value can slightly bump up or down the shutter speed from what the camera calculated.