Introduction to the Different Types of Camera Lenses

Introduction to the Different Types of Camera Lenses
Introduction to the Different Types of
Camera Lenses
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Lenses are one of the most important components in cameras. Even though the image making happens
inside the camera body and on the film itself, the lens is what handles the light and determines the
quality of the resulting image. You can’t really hope to take a picture without a lens, so it is important to
understand how they work.
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We can tout out versions of mushy phrases about hi-def equipment, but at the end of the day,
photographers that are perfectionists need to
know what they’re doing and what their
equipment is capable of.
How Does a Lens Work
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In the spirit of learning, let’s talk lenses. A
lens is basically an assembly of different
elements which help focus light onto the film
and remove any aberrations. You can attain
decent exposure using a simple pinhole
camera, but it will not be of high quality. In
fact, it’ll appear blurry. Although such
imagery has its own quaint charm, it is not
what’s always desired. Plus, you can’t increase the size of the hole to get a coherent image.
In its simplest form, a lens places a glass convex lens where the pinhole is so the aperture can be opened
wide to let more light in and make faster exposures. Through the lens, the light can still be properly
focused to get a sharp image. But it’s really not that simple, lens assemblies are complex and have
various other glass elements that help fine tune the quality of the image further.
The main factors that are used to define lenses are focal length and aperture, which control the angle of
view and amount of light respectively. Various lenses play with these two elements to help produce
quality photographs.
Focal Length
In simple words, focal length is the distance between the optical center and the film plane. The optical
plane is the point where multiple rays of light from the object entering the camera converge or cross
over. You might ask why this matters. Well, this distance is what determines your angle of view, as well
as the magnification of the image.
What this means is that the wider the angle of view is, the shorter the focal length becomes. Imagine
this as two triangles pointing at each other with the two bases being the object and the film plane. The
wider these get, the shorter the height of the triangles. In the same way, a narrower field of view would
be achieved with a longer focal length.
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Focal length can also determine subject magnification, especially where lenses have variable focal
lengths as in a zoom lens. As you increase or decrease the focal length, the subject can start looking
smaller or bigger. In certain cases, the focal length also affects perspective, mostly in architectural or
landscape shots where the subject fills the frame. Shorter depth of field can elongate perspective,
making closer objects look much closer and bigger, and objects further away looking distant and smaller.
On the other hand, longer depth of field can flatten or compress the subject.
Aperture
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Focal length is measured in millimeters, and is used as the lens name. For example, 50 mm or 200 mm.
Different lenses have different focal lengths. Wide angle lenses have a very short focal length, usually
between 10 mm and 42 mm, whereas telephoto lenses have anything between 100 mm and 800 mm.
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The second most important element is the aperture, which a lot of you may already know a bit about
since it is an integral part of controlling exposure. The aperture is the lens opening which controls the
amount of light that enters the camera and also determines your depth of field. It is denoted by an f
number, which looks like f/n or f:n. f is not focal length, and the number reflects the diameter of the
opening. However, this confuses a lot of people since the number decreases to denote a larger opening.
The reason for this is that f/n is basically an equation of sorts which gives you the diameter. So if your
focal length is 50 mm, and your aperture is closed down to 22, your aperture diameter is 50÷22=2.27
mm. Subsequently, every time the number decreases, the diameter would increase as the focal length is
divided by a smaller number and vice versa.
Usually the lens will come with its widest possible aperture printed on it, which is because this is usually
more important when considering flexibility in terms of exposure and depth of field. Lenses with wider
maximum apertures (smaller f numbers) are considered to be faster as you get more light in. This results
in the ability to shoot images at faster shutter speeds. This is of course desirable especially for low light
situations. Prime lenses tend to be faster lenses, while zoom lenses may have a range of maximum
apertures, which denotes the maximum apertures at different focal lengths.
Minimum apertures are usually not mentioned on lenses because most people never use them due to
blurring affects caused by lens diffraction. Similarly, it is advisable to shoot as 1 or 2 stops down from
the maximum aperture for the best results. However, it is always desirable for a lens to have a wide
range of apertures for flexibility in exposure setting.
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Types of Lenses
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Variations of these factors in lenses should determine the type and quality of lens and pictures you get.
A basic standard lens which sees the way our eyes see is different for different formats. 50 mm lenses
are normal for a 35 mm SLR camera, while for a medium format 6x6 camera an 80 mm lens would give
you a natural perspective. For the 4x5 format that fits a large format camera, a 150 mm focal lens is the
normally preferred choice.
However, this is not all that determines the types of lenses. Here’s a brief list of the main types of
lenses:
 Prime Lenses
Prime lenses have a fixed focal length, which means you cannot zoom in and out. Prime lenses
are considered to be of a much higher quality than zoom lenses and are easier on the wallet.
You also have the advantage of higher maximum apertures which means they perform really
well in low light settings.
 Zoom Lenses
Zoom lenses offer a range of focal lengths, for example 24 – 200 mm. The obvious benefit is
more control and flexibility in terms of perspective and composition, but you should know
having a zoom lens does not mean you can shoot pictures while moving around. Zoom lenses
are useful when you want a tighter shot or want to move in close without cropping the subject,
but they should not be an excuse for a lazy shot. It is still recommended you use your legs more
than the zoom.
With zoom lenses you have to compromise on quality, however, the various extra elements
available mean you have limited aperture settings and lesser light to work with.
 Wide Angle
 Telephoto Lenses
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As mentioned, lenses with shorter focal lengths are called wide angle lenses because of the
wider field of view they provide. These are usually 10 mm to 42 mm, and can be prime as well as
zoom. Zoom lenses may provide both wide angle and telephoto focal lengths depending on the
range they have. These are ideal for landscapes and architectural shots, and are great for getting
all the elements in a large area in, but of course there are no rules and you may use them for
any purpose. They give an interesting perspective with certain subjects because of how they
elongate the perspective. They also have a deep depth of field.
 Macro Lenses
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Telephoto lenses have a longer focal length, ranging from 100 to up to 800 mm. These lenses
can see great distances and provide a shallower depth of field. The field of view here is also
much narrower and they tend to compress the perspective and make things appear closer to
each other. All of this makes them ideal for wildlife, sports, and portrait photography. Again,
these can be prime as well as zoom lenses.
Macro lenses are used mainly for close-up or macro photography. They allow for sharp focus at
very close distances while objects further off would be completely out of focus. Their focal
length ranges from 50 to 200 mm, and they are used to photograph tiny objects with extreme
clarity.
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Equipment Matters
This was a small introduction to the different kinds of camera lenses to help you understand how they
function and how you can use them to create higher quality images.
While the quality of your images, the sharpness, resolution, focus, and brightness are all affected by the
lens you have, know that these cannot limit you. Even broken lenses can capture some great pictures.
Equipment matters but at the end of the day, it is the photographer that works the magic.
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