Basics of Photography 1

ISO, Aperture and Shutter

You may be taking photos with your camera set on AUTO. You will probably get totally acceptable pictures. However, understanding the relationship between ISO, Aperture and Shutter speed will help you to control these elements and produce even better photographs.

Combination of ISO, Aperture and Shutter forms, what is sometimes known as The Exposure Triangle. This is a set of guidelines that helps to understand the fundamental relationship to help us take better photos.

So to take a well exposed photo, certain amount of light is required to be allowed through the lens on to the sensor. I go through each of these 3 variables below and highlight the pros and cons of changing each one.

ISO

is the measure of the sensitivity setting. Higher the ISO settings, lower the amount of light you need. This allow you to take photos in low light by changing the ISO to a higher value such as 800 or above. So that’s the upside. How about the downside? The higher the ISO setting, the grainier the photos will look. If you don’t mind the graininess or that is the only chance you have to take the photo, then go for it. There are people who take grainy photos for artistic reasons.

Figure 1: Low light, high ISO, grainy photo

Aperture

Is the opening in the lens that let’s the light through to the sensor. The smaller the f number, the bigger the opening and hence more light is allowed through. Larger aperture will allow you to take photos with less light, for example evening and night time. However larger aperture means that for a given lens, the depth of field is limited. That means that once the camera is focus on an object, an amount of space in front and behind the focussed object is much smaller compared with a smaller aperture opening, represented by higher f number.

Figure 2: Remember – smaller f number means more light gets to the sensor

Figure 3 : Low f number, limited depth of field

Figure 4: High f number gives smaller aperature and greater depth of field

Shutter Speed

This is speed at which the shutter in the camera opens and closes to get the light to the sensor. Longer the shutter is open, the more light gets to the sensor and vice versa. Again, there are limitations here. If shutter is open for any length of time, any camera movement will get recorded, resulting in blurred photos.

Figure 5: fast shutter speed freezes movement of water

Figure 6: slow shutter speed blurs the movement of the water

So, let’s have a look at some scenarios when to change settings.

If you are thinking about venturing away from AUTO setting the camera, then I suggest you change to aperture priority. If there is sufficient light (day time) fix your ISO setting to 100, set aperture to f8 and let your camera select the shutter speed. Early evening? So not much light.

Do the following: increase your ISO to 800 and set the aperture to f4. Take photo. Camera will work out the shutter speed. Phot may be a bit grainy but at least you will have a well exposed photo.

You want to capture a fast-moving object. Unless you have fast enough shutter speed, your photo is likely to end up being blurred.

Do the following: Change the camera mode to Shutter priority and set your shutter speed to say 1/400. Set your ISO to 400. The camera will select the required aperture to expose the picture correctly. Now, these are suggestions and the exact settings will depend on the prevailing conditions – such as the amount of light and also the speed of the moving object. You will need to experiment with the settings.

Good luck and keep clicking.

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