“The lens sees what the eye overlooks, but it is in understanding how the eye sees that a photographer learns to use focal length not just to capture an image, but to shape a story.” – Unknown
Focal length is one of the most fundamental yet often misunderstood concepts in photography.
In technical terms, focal length refers to the distance between the optical centre of a lens and the camera’s image sensor when the subject is in focus, typically measured in millimetres (mm). This measurement directly influences the field of view and magnification of a photograph, determining how much of a scene will be captured and how large individual elements within that scene will appear.
In Canada’s diverse landscapes, from sweeping prairies to dense urban centres, understanding focal length enables photographers to select the right lens to tell their visual story with impact and precision.
Wide Angle
Short focal lengths, such as 14mm to 35mm, are considered wide-angle lenses. These lenses capture a broader scene and are ideal for landscape photography, architectural work, or environmental portraits. Their inherent distortion can be used creatively or corrected through post-processing.
Medium Angle
In contrast, medium focal lengths, typically ranging from 50mm to 85mm, offer a natural perspective closely resembling the human eye. These are often preferred for street photography, portraiture, and general-purpose shooting.
Telephoto
At the other end of the spectrum, telephoto lenses (typically 100mm and above) provide a narrow field of view with high magnification, making them essential for wildlife, sports, or isolating subjects at a distance, particularly relevant when photographing Canada’s vast wilderness or outdoor sporting events.
The Eye’s View
When discussing focal length in photography, it is useful to compare it to the magnification of the human eye to better understand how lenses interpret the world relative to our own vision.
The human eye does not have a fixed focal length in the same way a camera lens does, but it is generally accepted that the field of view and magnification of the human eye most closely resembles a lens with a focal length of approximately 43mm to 50mm on a full-frame (35mm) camera sensor. This range produces images with natural perspective and proportions, objects appear as we expect them to, without distortion or compression.
Lenses with a focal length shorter than 43mm are considered wide-angle and will appear to stretch or exaggerate the spatial relationship between objects. This can make distant objects look smaller and farther away than they would to the naked eye. On the other hand, telephoto lenses, which typically have focal lengths longer than 70mm, magnify the subject and compress spatial depth. This effect makes background elements appear closer to the foreground and is particularly useful in portraiture or wildlife photography.
Normal View
In practical terms, using a 50mm lens on a full-frame camera will produce an image with magnification and perspective similar to what we naturally perceive with our eyes. It is for this reason that 50mm lenses are often referred to as “standard” or “normal” lenses. For Canadian photographers documenting everyday life, travel scenes, or street photography, a 50mm lens offers an intuitive, balanced field of view that mirrors human vision with minimal optical distortion.
Understanding how different focal lengths relate to human vision allows photographers to make informed creative choices, whether they wish to replicate what the eye sees or intentionally alter it to enhance drama, intimacy, or narrative tension in their compositions.
Depth of Field
Focal length also affects depth of field and lens compression. Longer focal lengths tend to produce a shallower depth of field, allowing photographers to isolate subjects against a blurred background, a desirable effect in portraiture. They also compress the apparent distance between objects, making backgrounds appear closer and more prominent. Conversely, wide-angle lenses exaggerate the space between foreground and background elements, which can be leveraged to create dramatic perspectives or emphasize leading lines in composition.
Full vs Partial Frame
It is important to consider crop factor when using cameras with sensors smaller than full-frame, such as APS-C or Micro Four Thirds systems common in many Canadian photographers’ gear. These sensors effectively increase the apparent focal length due to their smaller size. For example, a 50mm lens on a Nikon, Sony, or Canon APS-C camera has an effective focal length of approximately 75mm to 80mm, depending upon the manufacturer, which significantly alters framing and field of view.
Conclusion
In conclusion, understanding focal length is not merely about selecting a number, it is about making deliberate choices in framing, storytelling, and perspective.
Canadian photographers, whether capturing the auroras in Yukon or street scenes in Montreal, benefit from mastering focal length to control both technical outcomes and creative intent.
About the Author:
Michael Martin is the Vice President of Technology with Metercor Inc., a Smart Meter, IoT, and Smart City systems integrator based in Canada. He has more than 40 years of experience in systems design for applications that use broadband networks, optical fibre, wireless, and digital communications technologies. He is a business and technology consultant. He was a senior executive consultant for 15 years with IBM, where he worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin served on the Board of Directors for TeraGo Inc (TGO: TSX) and on the Board of Directors for Avante Logixx Inc. (XX: TSX.V). He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology. He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now Ontario Tech University] and on the Board of Advisers of five different Colleges in Ontario – Centennial College, Humber College, George Brown College, Durham College, Ryerson Polytechnic University [now Toronto Metropolitan University]. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees, in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and seven certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has completed over 50 next generation MOOC (Massive Open Online Courses) continuous education in a wide variety of topics, including: Economics, Python Programming, Internet of Things, Cloud, Artificial Intelligence and Cognitive systems, Blockchain, Agile, Big Data, Design Thinking, Security, Indigenous Canada awareness, and more.