Camera basics – taking you through the basic settings on your digital camera.
When I was at school I wish my teachers had been as passionate about their particular profession as I am about Photography; Through experience after many years of Photographing people, landscapes and weddings, I do know that Photography is much more involved than learning the basics, its more about connection to your subject however I still believe that one has to understand the basics in order to help you meet any challenge facing you with your photography, you can face the challenge.
This is why I have put together this article; I’m pretty confident that it takes you through the basics of Photography and helps to explain those areas that you may have heard or read about; hopefully if you are just starting out or maybe even at college taking media, then maybe this may help.
Any questions or if you do happen to spot any errors please do get in touch with me either directly through my website – www.thefxworks.co.uk or email me.
CAMERA EXPOSURE MODES
Most digital cameras have one of the following standardised exposure modes: Auto (), Program (P), Aperture Priority (Av), Shutter Priority (Tv), Manual (M) and Bulb (B) mode. Av, Tv, and M are often called "creative modes" or "auto exposure (AE) modes."
Exposure Mode and How It Works
Auto () Camera automatically selects all exposure settings.
Program (P)Camera automatically selects aperture & shutter speed; you can choose a corresponding ISO speed & exposure compensation. With some cameras, P can also act as a hybrid of the Av & Tv modes.
Aperture Priority (Av or A) You specify the aperture & ISO; the camera's metering determines the corresponding shutter speed.
Shutter Priority (Tv or S) You specify the shutter speed & ISO; the camera's metering determines the corresponding aperture.
Manual (M) You specify the aperture, ISO and shutter speed — regardless of whether these values lead to a correct exposure.
Bulb (B) Useful for exposures longer than 30 seconds. You specify the aperture and ISO; the shutter speed is determined by a remote release switch, or by the duration until you press the shutter button a second time.
Each of these modes influences how aperture, ISO and shutter speed are chosen for a given exposure. Some modes attempt to pick all three values for you, whereas others let you specify one setting and the camera picks the other two (if possible). The following charts describe how each mode pertains to exposure:
The exposure triangle – How Aperture, Shutter speed, ISO
A photograph's exposure determines how light or dark an image will appear when it's been captured by your camera. Believe it or not, this is determined by just three camera settings: aperture, ISO and shutter speed (the "exposure triangle"). Mastering their use is an essential part of developing an intuition for photography.
Achieving the correct exposure is a lot like collecting rain in a bucket. While the rate of rainfall is uncontrollable, three factors remain under your control: the bucket's width, the duration you leave it in the rain, and the quantity of rain you want to collect. You just need to ensure you don't collect too little ("underexposed"), but that you also don't collect too much ("overexposed"). The key is that there are many different combinations of width, time and quantity that will achieve this. For example, for the same quantity of water, you can get away with less time in the rain if you pick a bucket that's really wide. Alternatively, for the same duration left in the rain, a really narrow bucket can be used as long as you plan on getting by with less water.
In photography, the exposure settings of aperture, shutter speed and ISO speed are analogous to the width, time and quantity discussed above. Furthermore, just as the rate of rainfall was beyond your control above, so too is natural light for a photographer.
A camera's shutter determines when the camera sensor will be open or closed to incoming light from the camera lens. The shutter speed specifically refers to how long this light is permitted to enter the camera. "Shutter speed" and "exposure time" refer to the same concept, where a faster shutter speed means a shorter exposure time.
By the Numbers. Shutter speed's influence on exposure is perhaps the simplest of the three camera settings: it correlates exactly 1:1 with the amount of light entering the camera. For example, when the exposure time doubles the amount of light entering the camera doubles. It's also the setting that has the widest range of possibilities:
A camera's aperture setting controls the area over which light can pass through your camera lens. It is specified in terms an f-stop value, which can at times be counterintuitive, because the area of the opening increases as the f-stop decreases. In photographer slang, when someone says they are "stopping down" or "opening up" their lens, they are referring to increasing and decreasing the f-stop value, respectively.
The above f-stop numbers are all standard options in any camera, although most also allow finer adjustments, such as f/3.2 and f/6.3. The range of values may also vary from camera to camera (or lens to lens). For example, a compact camera might have an available range of f/2.8 to f/8.0, whereas a digital SLR camera might have a range of f/1.4 to f/32 with a portrait lens. A narrow aperture range usually isn't a big problem, but a greater range does provide for more creative flexibility.
The ISO speed determines how sensitive the camera is to incoming light. Similar to shutter speed, it also correlates 1:1 with how much the exposure increases or decreases. However, unlike aperture and shutter speed, a lower ISO speed is almost always desirable, since higher ISO speeds dramatically increase image noise. As a result, ISO speed is usually only increased from its minimum value if the desired aperture and shutter speed aren't otherwise obtainable.
Common ISO speeds include 100, 200, 400 and 800, although many cameras also permit lower or higher values. With compact cameras, an ISO speed in the range of 50-200 generally produces acceptably low image noise, whereas with digital SLR cameras, a range of 50-800 (or higher) is often acceptable.
This mode weights exposure towards the centre of the viewfinder, as per the diagram above.
Centre-weighted metering works well if your subject is in the centre of the frame. If not, you have to point the centre of the viewfinder at your subject, hold the shutter button half-way down to lock in the exposure, then reframe.
Centre-weighted metering has been around a long time – if you own an old film camera it may be the only metering mode that it has. It’s predictable and easy to use once you understand that the camera is metering from the centre of the viewfinder.
Works just like spot metering but with a larger circle. Like spot metering, it works well for metering brightly lit subjects against dark backgrounds. You can use partial metering for taking a reading from a larger part of the subject than the spot meter.
Note: Evaluative metering is Canon’s term and the one that I’ll use in this teaching aide. Nikon uses matrix metering and Pentax and Sony use multi-segment metering.
Centre-weighted, spot and partial metering all take an exposure reading from the centre of the frame. Given that most photographers prefer to place the main subject off-centre for compositional reasons, this means that taking an exposure reading with one of these modes is not always the easiest way to work.
Evaluative metering was developed by the camera manufacturers to make it easier to measure exposure with off-centre subjects. The camera divides the viewfinder up into zones and compares exposure readings from each zone to come up with a suggested exposure setting. The above diagram shows the way the viewfinder is divided up into 63 zones on some EOS cameras.
The camera weights the exposure reading towards the active autofocus point (or points) as they are likely to be covering the main subject. It takes into account the readings from nearby zones and analyses the contrast of the scene to come up with an exposure setting.
Each camera manufacturer uses a slightly different process in their evaluative metering modes. While the manufacturers don’t release precise details of how their cameras calculate exposure in evaluative metering mode, there will be a guide in the instruction manual. It’s well worth a read so you understand how it works on your camera.
My preferred way of working is to use evaluative metering, take a photo, look at the histogram and then adjust the exposure if necessary. For me, this is the simplest way of arriving at the optimum exposure. However, everybody works differently and once you understand how the other metering modes on your camera work you may find one of the others is best for you.
Now that you understand more about your camera’s exposure modes, and why they may get the exposure wrong, you need to know what to do when the exposure is incorrect.
If you are using an automatic exposure mode, the easiest way is to use your camera’s exposure compensation function.
If you’re unsure how to set exposure compensation then check your camera’s manual – each camera is different. On mine, I just turn the Quick Control dial (circled above) on the back of the camera with my thumb. I like this way of working because I can dial in exposure compensation while looking through the viewfinder.
If the photo is underexposed, use exposure compensation to increase the exposure by a stop or two. Then check the histogram to see if the exposure is correct using the histogram.
If the photo is overexposed, you can use exposure compensation to reduce the exposure.
The Zone System basics
Zones are levels of light and dark.
A Zone System is a system by which you understand and control every level of light and dark to your best advantage. It works in digital just as it does for sheet film. Having a system allows you to understand and be in control, instead of taking whatever you get. Ansel Adams was asked in the 1950s if he thought the Zone System was still relevant in that then-modern world. He replied "If you don't use the Zone System, then what system will you use to know what you've got as you photograph?"
Spot metering for correct exposure: