Welcome to this workshop Basics of Photography. We will discuss the following aspects about photography: Aperture, Shutterspeed, Lenses and Sensors.
What is aperture
The aperture controls the amount of light going through the lens. This can be contolled by a ring on the lens to open the gap in the lens wider or more closed.
The numbers on the ring of the lens indicate how wide or closed the aperture is: example : 2 –4 –8 – 11 – 16 – 22
An aperture of 2 means that the lens is opened 1⁄2 or a half of total. With a aperture of 22 the lens is almost closed, not much light is going through the lens.
Why to use the aperture
So the aperture controls the amount of light witch is going through the lens. In the end the light is traveling through the lens to the image-sensor located in the back of the camera. For a good photo the image-sensor has to have the right amount of light. Not to bright, not to dark.
Since the aperture controls the amount of light, you can make a good shot by controling the amount of light with this feature.
What is shutterspeed
The shutterspeed controls when and for how long the light is coming in the camera to the image- sensor. When the photographer wants to make a photo, he pushes the button. Only then at that moment light is coming into the camera to captive the image. Mostly this is only a split second.
The shutterspeed controls for how long the light comes to the image-sensor. This is done by a shutter which opens en close very quickly.
What does shutterspeed
Just like the aperture, as explained in the previous chapter, the shutterspeed controls the amount of light on the image-sensor. With both features you can make a photo brighter or darker by manipulating these controls. The important thing is to set the shutterspeed and aperture to the right settings in order to get a proper photo, not to dark, not to bright.
The shutterspeed has specific numbers to indicate the speed of open up and closure. For example:
1000/sec – 500/sec – 250/sec – 125/sec – 60/sec – 30/sec – 15/sec – 8/sec – 4/sec – 2/sec – 1sec – 2sec – 4sec – 8sec – 15sec – 30sec
These numbers represent the speed in seconds devided by the number. So a speed of 125 means 125th of a second. 1/125
Sharpness and motion
The speed of the shutter also has effect on the sharpness of the photo. When you push the button to make a photo and the shutter is open en close very rapidly, the image will be sharp. But in the case when the shutter opens en closes very slowly, like 1 second, the image can be unsharp if the subject is moving.
For example, if you want to photograph a walking person and the shutterspeed is just set to 1 second, than the walking person will be unsharp. If you set the shutterspeed to very fast, like 125th of a second, the person will be ‘freezed’ and sharp.
Sluitertijd: 1” (1 seconde)
Sluitertijd: 125 (125e van een seconde)
The lens can be defined as the eye of the camera, like the human eye can make you see what you are seeing. The lens is capturing the image and brings it into the camera.
Types of lenses
There are different kind of lenses to mention. Each sort of lens have there specialities. Mainly there are 4 types:
- Wide angle lens
- Standard lens
Each lens has a specific range or angle of view, as explained in the picture below:
Wide angle lens
The wide-angle lens has a very wide range. When you look straight ahead you can only see some degree on the left and the right side. A wide angle lens has a more wider view than the human eye. It will give you a wide view of the picture. Common use of this type of lens is for documentary and landscape.
A standard lens is in between the wide angle and tele-lens. The angle of the view is about 45 degree, which is about the view of the human eye. The standard lens is usefull for many kind of purposes like portret, landscape and documentary.
A tele-lens brings subjects closer to you. The angle of view is very narrow as can be seen in the picture below. This lens is for example used for sports and wildlife photography.
An other type of lens is the zoom-lens. A zoom-lens is a combination of the lenses mentioned before and can zoom-in to wide angle, standard or tele- range, depending on the type of zoomlens you have.
|28 – 70 mm
||Wide and standard
|70 – 200 mm
||Standard and Tele
Lenses defined by Milimeters
Except for the name wide, standard or tele-lens we can define a lens more specific. That is done by the term milimeters, like 200mm lens.
The definition of lenses in milimeters comes from the lenght between the front of the lens to the backend of the camera. A static lens has a static number of milimeters, like: 28mm lens or an 200mm lens. A zoom-lens has a dynamic range. This means the lens is a 28mm to 70mm lens for example.
The image-sensor is a smale plate located in the back of the camera. The sensor is sensitive for light, captures the incoming light and converts it into an image.
How does it work
Each radius of light has a certain frequency. Depending on the frequency, the light will be red, green or an other color. For example, if a low frequency of light-radius is coming through the lens, the image-sensor will see this as red. A red pixel will be stored on the location where this light-radius was hit on the image-sensor. All light-radiations together will form an image.
The sensibility of the image-sensor is defined by the term ISO. The greater the sensibilty, the lower the light can be to be able to take a photo. In low-light situations you can set the ISO to a higher level in order to take the photo.
Example: How ever, there is a side-aspect to high ISO-levels. The higher the ISO, the lower the quality of the image. A high ISO-level like 1600, results in a grainy image.
Exposure of light
Important for the final image is that the exposure has to be right. This means, the white has to be white, black has to be black. If the white part of the images turn out to be gray, the photo is under- exposed. When black parts turn gray the photo is over-exposed, to much light came through the camera to the image-sensor.
How to measure light
The camera measures light by defining the average of the lightest part and darkest part of the subject. On auto-settings the camera will do that for you. But since it takes an average of the whole, you not always get what you want.
For example: if your subject is white, and you make a photo with auto-exposure, the result will be 18% gray. That is because the camera thinks in 18% gray.
In order to make this image as white as it should be, you have to over-expose 3 F-stops to make it white. For example if the aperture was f11, you have set it 3 stops more wider: f4. More light is coming through now.
F-stop means 1 step lower or 1 step higher exposure. If we look to the graycard above, we ‘ll see that it takes 7 steps to go from black to white. This means 7 F-stops. To adjust a F-stop you can use the shutterspeed, aperture or ISO to make 1 or more F-stops.
Example of 3 F-stops more light:
By Shutterspeed: 2000–1000–500-250–125–60–30–15: from 500to 60
By Aperture: 1.4 – 1.8 – 2 – 2.8 – 4 – 5.6 – 8 – 11 – 16 : from 11 to 4
By ISO: 50 – 100 – 200 – 400 – 800 – 1600 – 3200 : from 100 to 800
Controling the light
By controling the aperture, shutterspeed and ISO , you are able to control the exposure. All 3 aspects have impact on the exposure and depend on each other.