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. 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. The key is that there are many different combinations of width, time and quantity that will achieve this. You just need to ensure you don't collect too little ("underexposed"), but that you also don't collect too much ("overexposed"). 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. However, ISO speed is a setting that can rescue your photos in situations where neither of these is a realistic option.Achieving the correct exposure is a lot like collecting rain in a bucket. Using a wider aperture or a tripod may be a better option than increasing ISO because both will help you to shoot in low-light conditions, but without deteriorating image quality. However, your first priority should be getting a fast enough shutter speed, because a blurry photo is a lot more distracting than one with a bit of digital noise. You should always aim to use the lowest ISO setting possible, because this will give you the best image quality. If you do find that your photo has a lot of digital noise, you can use a program such as Neat Image to reduce it.
Noise is the digital equivalent of film grain, and it shows up as lots of tiny coloured dots, which are particularly noticeable in the darker areas of your photo.Īs ISO increases, noise becomes more prevalent, particularly in areas of flat colour.
Sadly, increasing your camera's ISO speed comes at a cost - it also increases the amount of digital noise present in your photo. This is fast enough to give us a sharply focused scene without having to resort to using flash or a tripod. This means that you need an exposure time which is only a quarter of the previous value, in this case 1/60th of a second. You could simply change your ISO setting from 100 to 400, making the sensor four times as sensitive. In order to expose the scene correctly you might need an exposure time of 1/15th of a second - far too long to shoot hand-held without ending up with a blurry scene. Let's say you're taking a photo of a church interior and have your ISO speed set at 100. Increasing your ISO setting can help avoid blur when photographing dark interiors without a tripod. Every time you double the ISO setting, you halve the required exposure time, and vice versa. These values are relative to one another, so ISO200 is twice as sensitive as ISO100, and ISO800 is four times as sensitive as ISO200, and so on.Īlong with aperture diameter and shutter speed, ISO speed is another factor in determining the required exposure time for any given scene. The higher the number, the more sensitive the camera is to light. With digital, you can adjust the ISO setting at the touch of a button because it is controlled electronically.Ī typical digital camera will have ISO values of 100, 200, 400, 800, and 1600 as a minimum. This means that if you want to use a different ISO setting, you have to physically change the film. Image by Timo.ĭigital cameras have a big advantage over film cameras when it comes to ISO - with film cameras, the ISO speed is a property of the film itself. ISO speed originated with film, and has carried over into digital photography. Because people were used to using ISO with their film cameras, the term was adopted in digital cameras too. Of course digital cameras don't use film, but they do use a sensor which works in a remarkably similar way. ISO speed actually dates back to film cameras, where it is used to describe how sensitive a particular film is to light. However, you will often need more control than this, which is why it's important to have a good understanding of camera ISO and how it affects your shots. Most digital cameras can automatically adjust their ISO setting to give an acceptably sharp image when hand-holding your camera. However, a high ISO also creates more noise, reducing the image quality. It is one of the crucial factors which goes into determining a photograph's exposure as well as the overall image quality.Ī higher ISO setting makes your sensor more sensitive to light, meaning that you can take photos in darker conditions without the need to use a flash or tripod. Your camera's ISO setting controls how sensitive its sensor is to the light that reaches it.
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