Assignment #14 -Focal Length

Due January 19th.

What is focal length?


The focal length of your lens essentially determines how ‘zoomed in’ your photos are; the higher the number, the more zoomed your lens will be.


It is often misunderstood that the focal length is measured from the front or rear of the lens when, in reality, it’s the distance between the point of convergence in your lens to the sensor or film in your camera, similar to a human eye.

Take a look at the diagram below that explains this:

Different focal ranges and what they’re used for:

A wide-angle lens exaggerates perspective, while using a telephoto lens gives the effect of compressing perspective, bringing elements closer together in the frame.

Ultra Wide Angle 14-24mm

These lenses are often considered specialty items and the range is not often included as part of a kit lens. They create such a wide angle of view that they can appear distorted as  eyes aren’t used to seeing that sort of range.

Ultra wide angle lenses are often used in event and architectural photography for getting a lot into a photo when shooting in a confined space. Wide and ultra wide lenses are about putting yourself in the middle of an event, rather than simply fitting in the whole of a scene.

HOWEVER: These lenses are not particularly suitable for portraits as they enhance the perspective so much that facial features look unnatural.

Wide Angle 24-35mm

This is where you’ll find most kit lenses for full frame cameras start. 24mm is roughly the point at which the distortion that appears to stretch the side of an image stops appearing unnatural.

They are used widely by photojournalists for documenting situations as they are wide enough to include a lot of the context whilst still looking realistic.

(All equivalent focal length means is that the angle of view is the same.

An iPhone 6 has a lens equivalent to a 29mm f/15 lens on a 35mm format camera.

In terms of a 35mm camera, the Galaxy Note is similar to a 28mm f/12.3 lens.)

These are still not considered flattering for portrait photography as they will still cause visual distortion, particularly to people standing too close to the edge of the photograph.  While a lower lens tends to be used for candid shots (see photojournalism reasons above), portraits are usually done with a higher lens.

Standard 35mm-70mm

It’s in this range (at about 45-50mm) that the lens will reproduce what our eyes see (excluding peripheral vision). I personally like to use this range when shooting on the street or with friends in a close setting such as at the dinner table or the pub.

A standard lens such as a 50mm f1.8 is an excellent, inexpensive addition for a camera and will provide excellent results. Prime lenses (lenses with a fixed focal length – can’t zoom) will always provide better results than your kit lens as it is built with a single purpose in mind; it does one job well rather than multiple jobs poorly.

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Mild Telephoto 70-105mm

This range is often where kit lenses stop and you’ll start to get into the range of telephoto lenses and portrait primes (around 85mm). This is a good range for portrait lenses as the natural perspective of the lens will separate the face from the background without completely isolating the face.

Telephoto 105-300mm

Lenses in this range are often used for distant scenes such as buildings or mountains. They’re not suitable for landscapes because of the way that they flatten the perspective of a scene. Lenses in a range higher than this are mostly used for sport and animal photography.

Focal length can be used to change the size of the background relative to the subject as shown below.  A telephoto lens will make the background look closer to the foreground.


The distance from the subject is what changes the perspective of a photo, and that goes hand in hand with focal length.

“To say it’s the focal length that changes the perspective is, however, quite misleading. You see, it’s actually the distance from the subject. The focal length is an indicator of the distance from the subject: the images are all framed the same; differences arise because the focal length is getting longer (zooming in) as the camera moves further away from the subject. Remember, the distance from the subject is changing the perspective; the focal length is just used to compensate for this.”

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Your assignment is to pick an object, and take the same picture, with the same framing, one with a small focal length and one with a longer focal length. To get the same framing, you’ll need to move back and forth.

For camera phones, take a photograph and then take the same photo with the same framing but with zoom in use.

See below for examples.

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Email both photographs with your name, date and assignment information from your school email. CC yourself as a record. This is due January 19.


Also, those that forgot to send a picture from around the school as a yearbook assignment need to email one to me.  (I will forward to the yearbook account.) Five will be required before the end of the year, this is the 2nd one requested and needs to be emailed by January 19th for credit.  If anyone sees something worth photographing around school (on a field trip, at a dance, fundraiser, or event), go ahead and send it early and it will be counted for future yearbook assignments.  MUST BE LABELED YEARBOOK ASSIGNMENT IN SUBJECT LINE.



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