Focal Length and Composition Photography Guide

Focal Length and Composition Photography Guide

One of the biggest questions when shooting a scene with an interchangeable lens camera is what focal length should I use in order to capture the scene I intend to? The answer may seem as simple as picking a lens where your subject fills the frame but the truth is that there are more factors to consider than whether your subject fills the frame. The questions you should also ask are how does my foreground and background look in relation to each other? How is my focal length affecting my perceived plane of focus? How does my focal length affect the perceived size and shape of objects in the frame? These questions are important to ask, especially when you are choosing lenses to optically portray your scene.

The first question to ask when shooting a scene is whether a wide angle lens, a normal lens or a telephoto lens will be the best option for shooting a scene. The definition of what constitutes as either a wide angle, normal, or telephoto lens depends on factors such as how the lens gathers  the light from the scenery and the size of your sensor in relation to the focal length. In consumer camera equipment like DSLRs and mirrorless cameras, the focal length of the lens is described in relation to what the focal length would be on a 35mm film stills camera which has a frame area of 36mm wide by 24mm tall. Digital cameras with sensors this size are referred to as “Full Frame” cameras. Most digital interchangeable lens cameras use a sensor which is smaller than this leading to a cropping of the image which is measured by a crop factor multiplier. 

For cameras which have a 35mm “Full Frame” sensor, the categories of lens types are as follows:

  • Under 20mm: Super Wide/ Fish-eye depending on if the lines are rectilinear.
  • 20-35mm: Wide angle
  • 35-75mm: normal.
  • 75-400mm: Telephoto
  • 400mm+: Super Telephoto

For cameras with smaller sensors, multiply these numbers by the crop factor of yor sensor. For example, Canon APS-C sensors multiply the labeled focal length by 1.6x so a 50mm lens on a full frame camera has the equivalent focal length of an 80mm lens when placed on an APS-C camera meaning that a full frame camera with an 80mm lens has the same angle of view as a 50mm lens placed on a APS-C camera with a 1.6x crop factor. This means that a lens may fit into different categories depending on the size of the cameras sensor. Below are examples of uses for each type of camera lens.

Super wide angle and fish-eye lenses are great lenses to use in applications like confined spaces and sky photography where the angle of view needs to be as wide as it possibly can. I have used super wide angle and fish-eye lenses for applications such as astrophotography due to the scale of the night sky, cloud photography for the same reasons, confined indoor spaces such as observatories and planetariums. Some of the drawbacks of super wide and fish-eye lenses include the distortion of straight lines caused by the lens compressing the image onto the sensor and foreground/background separation are extreme! Foreground objects appear gigantic while background objects look microscopic. 

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This image was taken with an 8mm f3.5 fish-eye lens on a full frame camera. Notice how the horizon is curved and the vignetting on the corners of the frame. 

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This Image was taken on an 8mm F3.5 lens mounted on an APS-C sensor camera giving the lens an effective focal length of 13mm. Notice the curvature of the horizon.

Wide angle lenses are great lenses to use in applications such as landscapes, interior photography, astrophotography, and architectural photography. Wide angle lenses are great for getting a large background behind your subject without a noticeable distortion that a super wide angle lens would have.  Wide angle lenses as well as super wide angle lenses are also good for achieving deep focus at lower apertures such as F2.8 due to the way these lenses stretch out foreground and background making these lenses great to use in low light situations. The drawbacks to using a wide angle lens are similar to super wide angle lenses but to a lesser extent. 

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This image was taken on a 24mm 2.8 lens using a full frame camera. Wide angle lenses like this are perfect for photographing the core of the Milky Way which covers a great expanse of the night sky. Also notice how the horizon is level.

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This image of the Battles of Saratoga Monument  was taken with a 24mm lens at F16. This image highlights how wide angle lenses can be used in architecture and how deep their plane of focus is.

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This image I took of Plattsburgh Bay with my 24mm lens at F22 highlights one of the disadvantages of using a wide angle lens. The foreground and background in this picture are stretched out to the point that you can’t see Mount Mansfield in the distance. I retook this photo with a telephoto lens below in the telephoto section of this article. 

Normal lenses are great lenses to use in applications where you would like to have your foreground and background proportions look as they do to the human eye being neither expanded like they are in wide angle lenses or compressed like they are in telephoto lenses. Applications in which normal lenses are used include portrait/landscape photography where you want the proportions of your subject and background to look as natural as possible.  

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This photo of me taken by Frank Cavone illustrates the properties of a 50mm F1.2 lens. Normal lenses are known for faithfully representing the size of foreground and background objects from the perspective of the human eye. The Adirondack bench and Fort William Henry appear as they do from the human eye albeit out of focus due to another advantage of normal lenses. Due to the simplicity and relative low cost of producing these lenses, they often have larger apertures leading to a shallower depth of field and better low light performance.

Telephoto lenses are great lenses to use in applications where you would like to be able to reach a subject far away from your lens. Telephoto lenses can also make foregrounds and backgrounds appear closer together. Applications where telephoto lenses can be used include wildlife photography, sports photography, or any other application where you need more reach. The drawbacks of telephoto lenses are that they also compress the focal plane making it seem to have a shallower depth of field. This can make it very difficult to have both foregrounds and backgrounds in focus without closing your aperture.

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This photo taken with a 135mm lens at F22 on a full frame compared to the photo taken with the wide angle lens shows how it is sometimes better to use a telephoto lens for a picture instead of a wide angle and vice-versa. Notice how the pyramid in the foreground is relatively the same size as it is in the picture taken with the 24mm lens and how the retaining wall as well as Mount Mansfield appear to be larger in the frame despite Mansfield being 33 miles (53 kilometers) apart from where I’m standing!

Super telephoto lenses are great lenses to use in applications where you need to reach as far as possible in order to have your subject fill the frame.  Applications where super telephoto lenses include sports photography, wildlife photography, deep sky astrophotography, moon photography, and solar photography (NEVER LOOK DIRECTLY AT THE SUN!!!!!! USE AN APPROVED SOLAR FILTER TO PROTECT YOUR CAMERA AND MAKE SURE TO READ THEIR WARNINGS!!!). The drawbacks of super telephoto lenses are that they are nearly impossible to use without a sturdy solid tripod due to their magnification of camera shake, lens/camera image stabilization is a must making these lenses more expensive, and they rarely are ever made faster than F4 due to the amount of materials needed to build lenses with those specs.

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This image was taken with a 200mm 2.8 lens on a 3X teleconverter, a  Lens mount adapter that magnifies 1.4x and a camera body with a 1.6x APS-C crop gives this lens an equivalent focal length of “1200mm”! This image depicts a female Ruby-Throated Hummingbird at a feeder. The bush in the background is 5 feet away (1.5 meters) but appears to be only inches away due to the properties of this lens. This photo was taken 15 feet away (4.5 meters) inside a living room. 

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This picture was also taken with my “1200mm” rig. Super-Telephotos are perfect for photographing the moon in a manner which fills the frame.

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This image taken with an approved solar filter of the 2017 solar eclipse was also taken with my “1200mm” lens since the moon and the sun are coincidentally the same relative size in the sky from our perspective.

Hopefully this helps you choose which lens to use on the next adventure with your camera. If you are just starting out I recommend buying your camera with a kit lens to get a taste of what direction you would like to go next when you upgrade your lens collection. A cheap start to your lens collection would be a prime 50mm 1.8 which most companies sell for 100-200 USD and then either go for a wide angle or telephoto lens depending on your taste.

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