Camera exposure

By Antony Obuya

You can greatly improve your photography skills by understanding how exposure affects digital cameras. Exposure is simply the amount of light you let into the camera. Most digital cameras can sustain exposure error but only to a certain extent. If the exposure is too little, your photos will appear darker and if there is excessive exposure, the photos will be washed out.

Application of certain software can however correct this. The software is used to make the poorly-exposed image presentable.

This is however discouraged due to a number of factors some of which are listed below;

1) Correcting a poorly exposed image is also a waste of time, a reason why you should ensure that your first shots are done accurately.

2) Certain lighting conditions can do tricks on a camera affecting its lighting meters.

3) Finding a good colour saturation point is also another problem that comes with poorly-exposed photos.

4) With poorly-exposed images, you will find it hard (almost impossible) to get a good contrast.

5) By overexposing a camera, you will end up with blown highlights meaning that you will never get to recover relevant detail in such a photograph.

6) Underexposure also does the same ting causing blown highlights. Just like in overexposure, you cannot recover detail here because there is no data recorded under such conditions.

As the information above clearly indicates, you should have complete knowledge of what exposure is before you even try to take a photograph.

Because digital SLR owners usually have limited choices when it comes to adjusting exposure, this information is basically intended for them. They normally use compact digital cameras which automatically control exposure. But still you should delve deep into this information and know how such cameras operate. This will provide you with added knowledge especially if you are looking to buy a digital SLR in the future.

In case you prefer a digital SLR that controls exposure for you, you might the information here discouraging. However, if controlling exposure by yourself is something that interests you, this page clearly shows you how to do so.

Understanding What Affects Exposure

Basically, three factors affect exposure in a camera with two factors relating to the amount of light that a camera receives. The three are factors are;

The film speed
The shutter speed (refer to creative use of shutter speed)
The aperture (refer to depth of field)

Understanding Exposure With Respect To Aperture

Knowing what Aperture is and what it does is also important if you want to fully understand the whole aspect of exposure. Just like shutter speed, Aperture is a way on how the camera controls the amount of light that it receives.

An adjustable hole in the lens of a camera, the Aperture opens to allow more light in. It can also stop too much light from entering the camera by becoming a tiny hole on the lens.

Note that both shutter speed and Aperture work together. A slower shutter speed will let in more light meaning you have to close the Aperture to counter this. The reverse applies. A faster shutter speed will allow less light to enter the camera. Therefore, to balance this you have to open the Aperture to let in more light.

If you want to learn more on how an Aperture can creatively control depth of field, find the explanation here.

Understanding Exposure In Relation To Shutter Speed

You cannot grasp what exposure is without understanding shutter speed. This can be described as the length of time at which the shutter stays open. When the shutter is open, light then comes in the camera and finally falls on the image sensor. If the shutter stays open for long, the camera receives more light and if it is left open for extended periods, the final image will be overexposed. And if the shutter is left open for quite a short time, the final image will be darker.

Bear in mind that the amount of time in the entire process is measured in a fraction of seconds whereby 1/30th of a single second is considered to be slow. Digital SLR can however attain shutter speeds exceeding 1/4000th per second.

For more information on how to use the shutter speed for creative effects and how it affects exposure, click here.

Understanding Exposure With Regard To Film Speed

If you are really keen on learning about exposure then film speed is an important aspect of photography you should not ignore. Seriously, film speed or ISO affects exposure. Let me take you through the basics……

In the past before taking photos, we would load our cameras with films the common one being ISO 100. The ISO rating was given depending on how the film was sensitive to light. So the ISO 100 proved to be good sport in days when there was good light. However, when the light levels dropped, we had to widen the aperture and slow the shutter speed.

There was however one main problem with this adjustment. If you widen the Aperture it lets too much light in. And with the shutter speed at its lowest point, you had to avoid blurring the shot by holding the camera steadily. We ended up loading the camera with additional light-sensitive film because the light was not enough.

From the previous ISO 100, the film’s rating or sensitivity doubled to ISO 200, then to ISO 400 and so on. In those days, there was a maximum of ISO 6400 which was only sold in pro shops. Therefore, the highest ISO rating you could get as a consumer was ISO 1600.

You may be wondering what all this has to do with digital photography. The thing is, with Digital SLRs you can set the ISO manually such that if it get darks, you can increase the ISO. The main shortcoming of digital SLR is that it comes with a speckling noise that affects photos. We also encountered this noise back then where we called film grain. This was in the days of film where more speckling noise came with higher film speed. Note that this noise has its positive aspects as it can also be used to good effects.

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