Wanneer je beter wilt leren fotograferen dan is theorie niet onbelangrijk. Wanneer je over fotografie leest kom je snel technische termen tegen. Voor de meeste fotografen zijn deze termen zo ingeburgerd dat ze niet verder uitgelegd worden. De onderstaande opsomming is bedoeld voor mensen die niet of minder bekend zijn met deze termen. Als je ze wilt opfrissen kan deze tekst zeker ook helpend zijn.
This is the size of the lens opening which determines how much light will go onto your camera’s sensor. It is measured in ‘f- numbers’ or ‘f-stops’ (explained later in this chapter), which are calcu- lated by dividing the aperture’s diameter by the lens’s focal length. In other words, a 50 millimeter aperture on a 200 millimeter focal length lens will have ¼ f-stop, which is commonly written as 1:4, f4 or F4. As a rule of thumb, the higher the f/stop, the lower the aperture value. The aperture value has a significant impact on the DOF (depth of field, also explained later in this chapter) of the picture. A smaller aper- ture value will result in a larger DOF effect. The way DSLRs can use var- ious values of aperture to control DOF is a distinct advantage over com- pact digital cameras that have neither the sensor size nor the focal length to match the DOF capability of DSLRs.
Depth of field
Simply put, depth of field (or DOF) measures how much of a picture, besides the main subject, stays in focus i.e. how much of the foreground and the background of the subject is sharp after the picture has been taken. Focal length, aperture and distance from the item all affect DOF. For example, a large aperture (an f/stop of 1:2) will have a shallower DOF ef- fect, with the large part of the background and foreground out of focus. This setting is typically used for portrait photographs where you want the picture to focus primarily on the subject. As you move closer to the subject, the DOF will decrease, whereas moving away from the subject will increase it. A DSLR camera equipped with a lens that has a smaller focal length will have a larger DOF. Your DSLR may also be able to preview the picture’s DOF before you have even taken the shot. This feature is known as ‘optical preview’ or ‘DOF preview’.
This is how much light reaches the DSLR’s sensor, and is determined by the shutter speed (discussed later on) and the aperture size. The ISO setting (also discussed later in this chapter) will also have a considerable effect on the impacts of various exposure settings. The exposure value is obtained from a combination of ISO, aperture and shutter speed settings. Zero EV is a result of an aperture value of F/1, an ISO sensitivity of 100 and a shutter speed of 1 second. If you’re taking pictures in a bright setting, set a high EV value to minimize the risk of overexposure (too much brightness in the final picture) due to an aperture value that is too large or a shutter speed that is too small.
According to the textbook, focal length (measured in millimeters) is the distance from the lens’s optical center to the camera’s sensor, when the subject of your picture is completely in focus. How- ever, this won’t give you a very good idea of its importance. In simple English, a lens with a shorter focal length will require you to get up close to the subject for a close-up picture. A lens with a longer focal length will let you take the same close-up picture from a longer dis- tance. If your camera has a zoom lens, it means that its focal length is variable. On the other hand, if your camera has a prime lens, the focal length will not be changeable.
Also written as f/stop, or f-number, it is a measure of the rela- tive aperture size of your camera’s lens. As mentioned before, it is ob- tained by dividing the aperture size’s diameter with the lens’s focal length. Since f-stop is basically a fraction, a higher f-stop value indicates a smaller aperture size which means a lesser amount of light will hit the sensor. ISO: This variable goes back to the days of film cameras, and is the definition of speed (or sensitivity) of the color negative film, according to the International Standards Organization. A higher ISO rating means that the film will be more sensitive to light. In other words, an ISO rating of 100 would be great for normal day time photography, but higher ISO speeds would be required for dimly lit or fast moving settings. Taking things to DSLR photography, the film speed is replaced with the sensor’s sensitivity. This means that an ISO value raised to 400, 800 or possibly 3200 would require very little light to capture an image.
Raw refers to an unprocessed digital image i.e. raw. It is a file format, a full download of what the camera’s sensor observes before the picture is processed. Consequently, RAW files take a longer duration to get written on the camera’s memory card and also take up more space. However, they are much more flexible to post-processing effects (effects added after the picture is taken). Moreover, memory cost is getting lower every day, and software such as Photoshop is getting much better at ma- nipulating RAW images, which is why this format is getting more popular as well.
The shutter speed refers to the actual time for which the shutter is open and let’s light reach the sensor. It is measured in seconds. The lower the shutter speed, the shorter the time for which it will remain open. A longer shutter speed is useful for dimly lit settings such as night time, as well as for lending a fast motion effect to objects.