Posted by Happy Hippo on 12/18/2009 12:55:00 am
Every photographer must know the things that I list below, and understand what they do and what kind of effect they produce when changed to particular values:
If you have any questions, leave a comment. Thanks.
- The Shutter speed: this is the time that the camera sensor is exposed to light. So, if you set slow shutter speed, the sensor will be exposed to light for longer time than if you set it to fast shutter speed. Fast shutter speed is usually used for fast-moving objects, because in a very short time interval, that object is almost stationary (like a snapshot), and it comes out sharp and clear. Slow shutter speed is used when you want to achieve motion blur on a stationary background: e.g. a light trail/shadow of a moving car on a stationary background of a city or "ghost" shadows, or other creative techniques like light drawing. On Canon 400D this is done by going to manual mode and then rotating the wheel near the shutter button. Common shutter speeds are: 1/800 (one 8 hundreds of a second: very fast) is used for sports/racing, 1/200 is used for general photography/macro, 1/50 is used for portraits sometimes, 1/10 (slow) is used to get some motion blur, 1 second is used to get even more motion blur, 20/unlimited seconds is often used for light painting.
- The Aperture or F-stop: this setting allows you to set the size of the hole in the lens, allowing more or less light to go through to the sensor. Obviously bigger aperture (but lower F-stop) makes it possible to use faster shutter speeds (because less time is needed to properly expose the sensor to light) and vice-versa for smaller aperture. But this setting has another effect, called the depth of field (see below). Again, bigger aperture makes the depth of field more shallow, and smaller aperture makes it greater. Common values of this are: F22: very small aperture, needs very long exposure time (very slow shutter) and is used in e.g. light drawing; F12:small aperture, also needs slow shutter speed, but can be used for bright situations, F8, F6, F4.5, F4: very common general shooting apertures, require standard shutter speeds, and F4 is usually the maximum aperture on budget lenses; F2.8: is a very big aperture lens, these lenses are usually very expensive, but allow very fast shutter speeds/low light photography.
- The Depth of Field: this is not actually a setting, but more an effect you can easily change (and you need to think what kind of depth of field you want when taking any picture). As I mentioned before, this is achieved by varying the aperture and conversely the shutter speed (shutter speed is just to achieve the correct exposure, but the DOP is mostly set by the aperture setting). Some cameras (e.g. Canon 400D has a button that shows DOF preview)
- Sensor sensitivity or ISO: this setting let's you change the sensor sensitivity, and therefore adjust it for bright/low light situations. ISO of 100 is a common lowest sensitivity setting, that needs longest shutter speed for proper exposure (or/and higher aperture), it's good for day-light photos. Other common ISO settings are 200, 400, 800, 1600. That last one obviously is the most sensitive, low-light oriented setting. But generally you should aim for the lowest ISO possible, because the higher the sensitivity, the more noise you get. Noise is multi-coloured dot's on you image.
- Colour balance: your camera takes analog visible light and maps it to a digital representation of colours (i.e. from infinite variety of analog colours to a map of many millions of colours, also know as a colour space). But how obviously different screens or printers display colours differently, so this setting allows you to slightly vary the colours of this colourspace, to match your device. Automatic setting usually gives good results, but sometimes you can set it to other custom values if you think it doesn't look very natural, e.g.: 7000k setting is used when you have a lot of shadow, 3200k , slightly bluish tint.. etc (it usually says in the camera manual).
- The light-meter, exposure: every DSLR camera has a light-meter that you can see if you look through the view-finder or on the LCD screen before taking a picture. It usually is just a line with a small indicator. For balanced exposure you want the indicator to be exactly in the middle. Otherwise if the indicator it shifted to the right, you'll get overexposed images and vice versa if it's to the left. In manual mode, you just change the aperture and shutter speed, until the indicator goes to the middle, you cannon move the indicator itself. But in semi-automatic modes on Canon cameras (e.g. 400D), the indicator in always in the middle, because all other setting are selected automatically to make it stay there, but, if you don't like it and want your image darker or brighter, but still stay in semi-automatic mode, you can set "Exposure compensation" setting, by moving the indicator to the left or right (see your manual).
- Lens focal length: I have already mentioned in my previous posts what types of lenses exits (in 1.6x format): 7-12mm: fisheye lenses, that give distorter images but extremely wide angle, 12-24mm: wide angle lenses, 24-70mm: standard lenses (no magnification), 70-500mm: telephoto lenses, dedicated macro lenses. It's quite easy to use lenses once you have them, especially with autofocus and multiple focus, but a word of caution: when using macro lenses or 100-500mm lenses, you definitely need a tripod, because every small hand movement adds a lot of blur, the higher the magnification, the bigger the effect. And also, maximum lens aperture decreases when you increase the focal length, so you need to be aware of that.
If you have any questions, leave a comment. Thanks.