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Digital Camera Basics for the Aquarium Photographer
by Evan Bowers

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I hear a lot of basic questions about cameras and photography so I thought it would be useful to put an article together. This article will attempt to do three things. The first is to provide a high level overview of how cameras work. The second is an attempt to answer the question I hear most. "What do I need to buy?" Lastly, we will discuss the most import camera settings for aquarium photography.

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In order to do all that, I will first need to introduce a little bit of photography theory. The first part will be the most complicated, but bear with me through the theory and then we can get to the good stuff.

How Cameras Work - The Basics

There is a lot of complicated theory that describes how a camera works. Luckily for us, we don't really need to understand that much of it to be able to take pictures. However, there are a few basic concepts that will really help us out. Photographers use these basic principles in everyday shooting.

Digital Sensor

In a traditional film camera the film is what records the light coming into your camera and turns it into a picture. In a digital camera, there is a sensor inside your camera that does the same thing as film, it turns light into pictures. The sensor is sometimes called "digital film".


The aperture of a camera is simply the hole in the lens that the light comes through. A bigger opening means that more light can come in, a smaller opening means it is harder to get light in. If a lens has a big maximum opening it is called a "fast" lens. If a lens has a small maximum opening it is called a "slow" lens. Aperture is typically referred to in f-numbers sometimes called f-stops. The smaller the number, the larger the opening is. For example, a lens that is rated at f/1.2 has a huge maximum opening and one that is rated at f/5.6 has a much smaller maximum opening.

OK, I know that was a whole bunch of information to start with but really the key thing to remember from all that is that the aperture is the opening the light comes through.

Shutter Speed

In order to explain shutter speed I first need to explain what a shutter is. As is relates to a camera, a shutter is a little gate that blocks light from getting to your sensor. In the same way that real shutters will stop the light from coming through a window. The shutter is normally closed but it opens up to let light through to your sensor. Shutter speed simply refers to the amount of time that the shutter is open. That is all there is to it, simple right?

So now we know that the sensor is our film, the aperture is the hole in the lens that the light comes through and the shutter speed is how long the shutter is open for. Now we need understand how all that is related and why it is important.

Putting it All Together

It is actually pretty simple. The first thing to note is that just like film, the picture that the sensor records is very sensitive to light. The more light we let in, the brighter the picture is. For example, a typical shutter speed in normal light is between 1/60th of a second and 1/250th of a second. So, given how fast this all happens, the timing of it is very important.

The amount of light that comes in is controlled by both the aperture of the lens and the shutter speed of the camera. The bigger the aperture, the faster the shutter speed needs to be to let in the proper amount of light(This is because a bigger opening lets in more light). In the old days, you had to take a light reading with a meter and then set your aperture and shutter speed by hand. Today, modern cameras have a light meter built in and can set the aperture and shutter speed on their own.

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So, now you're thinking, if the camera can do all this automatically, why did we spend all this time to learn about it? It is because both these things have a big impact on how your pictures look. You are going to see both the aperture and the shutter speed every time you look through your camera. Even though you probably will not think about these things when you first start using your camera, understanding what they do will help your photography in the long run.

The Effect of Shutter Speed

What shutter speed does is actually very simple. A short shutter speed freezes the action and a long shutter speed will make moving objects blurry. In addition to the subject moving, we have to worry about our hands moving. A very small movement of the hand can make a picture very blurry. A faster shutter speed will make this less of an issue.

So why wouldn't we always use a fast shutter speed? Well, because sometimes we can't. As we discussed previously, the speed of the shutter is related to the size of the aperture. If the aperture isn't big enough then we cannot set the shutter speed as high as we would like. This is one of the advantages of a "fast" lens. A "fast" lens, that has a big aperture, allows more light to come in letting us set a faster shutter speed.

So how fast is fast enough? Generally, a good rule of thumb is that 1/(focal length of the lens) is the minimum shutter speed you should use. For example, if you are using a 60mm lens then the shutter speed should be at least 1/60. If you are using a 200mm lens then the shutter speed needs to be at least 1/200. The good news is that your camera can also take care of this for you. Modern cameras know what kind of lens you are using and will adjust accordingly.

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