This section covers Exposure, Aperture, Depth of Field, Shutter Speed, ISO, White Balance AND moving on from Auto
WHAT IS EXPOSURE?
In the simplest possible terms of how a camera works…
· You need a light proof box (i.e. your camera) a lens at one end and a light sensitive film/digital card at the other
· Light enters through the lens (Aperture) and after a certain amount of time (determined by the Shutter speed) an image will be recorded
· The recorded image is called an Exposure
· We all want Correct Exposure
On an iPhone you can change the ‘exposure’ by taping the screen to get the sun image. Then use the slider up and down to change how bright or dark the scene is.
On a DSLR you have the light meter built into the camera, which you can see at the bottom of the view finder. When the indicator is in the middle, the camera is suggesting this is correct exposure but you may have to manually change this to over or under expose to get the correct lighting for the scene you are photographing.
· On a DSLR the best way to get consistent and correct exposure is to use Manual mode
Here’s a brief explanation of the other modes.
· P Mode – is Programme Mode, this lets the camera make all the decisions for you
· TV Mode – Time Value / Shutter Speed Priority. You choose the Shutter Speed, so you make the decision about how sharp you want the image, select a fast Shutter Speed if you want to capture people moving. The camera then chooses an aperture and ISO to create correct exposure.
· AV Mode – Aperture Value / Priority. You choose the Aperture, so you make the decision about how much of the scene you want in focus. For portraits maybe a large aperture of F2.8 so the background blurs or a small aperture of F16 if you were doing a landscape. The camera then chooses the Shutter Speed and ISO to create correct exposure
· So, a correct exposure is a combination of three elements; Aperture, Shutter Speed & ISO
Aperture controls the volume of light reaching the film/digital card. Think of it as an eye, the pupil expands and contracts depending on how bright/dark it is. The aperture of a lens does the same.
· A large aperture allows in more light, compared to a small aperture.
The other important and creative point of aperture is Depth of Field.
· As well as controlling the amount of light, Aperture choice controls What and HOW MUCH of a scene is in focus
· At F2.8 focusing on a persons eyes, the eyes are in focus and not much else in front or behind will be. SHALLOW DEPTH OF FIELD.
· At F22 focusing on a persons eyes, the eyes are in focus as is pretty much everything else in front and behind the subject. LARGE DEPTH OF FIELD.
What is an F-Stop?
Traditional F Stops are F/1.4, F/2.8, F/4, F/5.6, F/8, F/11, F/16, F/22 (now DSLR have all sorts of F-stop numbers in between the above too)
· Your camera may just show the number as F1.4 F2 but the important thing to note is that these numbers are actually written as fractions. f/8 is 1/8 f/16 is 1/16
· This means, 1/8 is bigger than 1/16 so therefore an aperture of f/2.8 is much LARGER than an aperture of F/22
· Therefore the LARGER the aperture the LARGER the opening, allowing more light to come in and to achieve this you’d be using apertures of F/1.4 F/2.8
· And by that logic the SMALLER the aperture the SMALLER the opening allowing less light to come in and to achieve this you’d be using apertures of F/16 F/22
· On a DSLR you can choose your F Stop, but the range available will depend on the lens you have. Some will start at F/4 not F/1.4
Shutter Speed controls the amount of time the light coming through the lens is allowed to stay on the film/digital card
· this can vary from 1/8000 to 30 seconds depending on your camera and are measured as fractions of a second
· therefore 1/500 is a 500th of a second
· 1/500 1/250 1/125 1/60 1/30 1/15 these are Full Stops from the film days but newer cameras have stops in between and can be as fast as 1/8000 of a second all the way to 30 seconds.
· Slower shutter speeds will give movement or blur in the image, fast shutter speeds will capture motion, like water droplets or children running
ISO (International Standards Organisation)
This is the Film Speed (you may remember before digital buying Kodka Sunny Film or Kodka Cloudy Film - Sunny had an ISO of 100 and Cloudy had an ISO of 400)
· 100 / 200 / 400 / 800 / 1600 /3200 these are the traditional film speed numbers and again DSLRs have lots of settings in between going up to 256000 and beyond
· The lower the number the lower the sensitivity of film/camera sensor is to light. The grain or noise will be less or not noticeable
· The higher the number the higher the sensitivity of the film/camera sensor is to light and the higher and more noticeable the grain/noise will be. You may notice if you try to take pictures in the evening or dark places that the images are really pixelated, this is grain or digital noise. It’s sometimes used artistically but generally this is not a good thing and something we want to avoid.
Light has a colour temperature, determined by the Kelvin numeric value, the scale is as follows:
· 1000-2000 K Candlelight
· (COOL / BLUE)
· 2500-3500 K Tungsten Bulb (household variety)
· 3000-4000 K Sunrise / Sunset (clear sky)
· 4000-5000 K Electronic Flash
· 5000-6500 K Daylight with Clear Sky (sun overhead)
· 6500-8000 K Moderately Overcast Sky
· 9000-10000 K Shade or Heavily Overcast Sky
· (WARM / ORANGE)
I generally leave my camera on AWB (Auto White Balance) it’s the only setting that I allow the camera to make the decision for me. Generally I’ve found my Canon’s are usually spot on with getting the colour temperature right. But this is something that can be corrected in Lightroom, if the end result is too warm or too cool.
If you made it this far, well done!
The basics about how a camera functions seems like hard work but I’ve always thought about it like driving a manual car. The gears, clutch control, biting points, mirror, signal, manoeuvre, it took me soooooo long to learn how to drive it was the most confusing, frustrating thing for me. But now do I ever think about any of those steps? No I just drive. And that is how learning how to use Manual Mode was for me, it was so frustrating but I persevered and practised and now it’s just instinctive.
If you are still in Programme mode and Manual seems too daunting, then switch to Aperture Priority. This will really help you with your creativity. Just look at the difference between the image shot with an aperture of F2.8 and one shot at F22, which do you find more appealing?
When going through this course, start asking yourself how much of the scene do I want in focus. Experiment by dialing up and down, start at your largest aperture on your lens, be that F/1.4 and shoot at the smallest F/22 what happens with the other choices the camera makes like the shutter speed? Is it too slow now to give you a sharp in focus image if you are hand holding the camera? Do you need a tripod? It will really help you get to know your camera and get to know your style. Perhaps you love everything in focus so you want to choose to use smaller apertures like F/22 or you love your images being a blur of colour so you shoot everything at F/2.
If you are not already in Manual Mode, start the first assignment in Aperture Priority please!