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How Does Focal Length Really Affect Your Photos?
Focal length - it's not the toughest thing to grasp. The greater the focal length, the greater the zoom (or magnification of a subject). The numbers, e.g. 50mm, refer to the distance between the optical centre of the lens and the digital sensor inside the camera's body. The longer the zoom, the narrower the angle of view, and vice versa.
That's it really! In a nutshell, that's where many explanations of focal length tend to finish. But what's the real impact of focal length on a photograph? How does it influence composition, emotion and the way a viewer repsonds to the image? Lets' explore...
First up, let's look at the 4 basic categories of lenses (guide to choosing a lens):
1) Wide angle. These feature a focal length of around 35mm or less (for a full frame sensor), offering a very wide angle of view.
2) Standard. 35-70mm is a standard focal length lens, which produces an angle of view broadly equivalent to that of the human eye. On a 35mm camera, 40-50mm is the closest equivalent to human vision.
3) Telephoto. Telephoto lenses span from about 70-300mm, zooming in close on a subject and constricting the angle of view.
4) Super-telephoto. Massive zoom of 300mm and up, producing a very small angle of view indeed.
So, if standard lenses roughly reflect our own vision, we already know what that's like! It's a great focal length to choose for lots of subjects, where you want to portray a subject realistically and clearly, such as street scenes, small group portraits and so on. But what impact to the more unusual wide angle and telephoto lenses have on the way we see things?
Wide Angle Lenses: Focal Length of 28mm Or Below
A wide angle lens takes in a broader scope of what you see in front of you. But in doing so it impacts the composition and character of an image in several ways:
1) Depth Perception. A small focal length increases the viewer's awareness of depth in an image. That's one of the reasons why it's so useful for landscape photography. By including foreground elements, which lead deeper into the scene and eventually the background, it's easy to give a real sense of the various planes that make up a picture.
2) Diagonal Lines. A small focal length/large angle of view often results in pictures with prominent diagonal lines. This is becasue of the way verticals become distorted, more noticeably towards the edges, and converge inwards. If you've ever tried shooting a city skyline with a wide angle lens you've probably spotted this. It can be easily corrected in Photoshop, but I actually think it looks pretty cool.
3) Viewer Involvement. Wide angle images seem to almost encompass you as the viewer in a way that no other images do. This effect requires a strong foreground to pull off successfully and, again, is a common quality of landscape photos. The nearest objects are very dominant, stretching out across the foreground and implying continuation of the landscape.
It's also a good device to employ in street photography sometimes too (decisive moment photography tips). Including buildings or people at the edges of the frame can add to the sense of being there, and the wider context.
4) Scale Distortion. Similar to the last point, objects in the foreground loom larger than they really are, relative to the rest of the image. This is useful for drawing the viewer in and creating a dynamic, interesting image. It can also be used to good comic effect: you know those weird portraits where the subject's nose kind of bulges towards the lens? Unflattering but funny - and also cute with animals (like my dog below!).
Telephoto Lenses: 70-300mm and Beyond
Telephoto lenses allow you to zoom in and magnify subjects at considerable distances. That's a great advantage, but it also has a big impact on composition and the feel of an image (telephoto lens tips for beginners):
1) Isolating Subjects. Telephoto lenses prevent you from showing the context of a subject. They enable you to really isolate something and separate it from it surroundings. A long zoom also exaggerates the effect of a wide aperture, by magnifying the out-of-focus background. This is great when you want to eliminate all distractions. Long focal lengths are ideal for portrait photos, where you need the viewer's attention to be soley focused on the face and expression of the subject.
2) Flattening/2D Effect. Whereas short focal lengths increase the feeling of depth, long focal lengths do the opposite. Telephoto lenses compress an image, bringing everything together on a single flat plane.
This isn't just a handy device for portrait photos, but can be quite fun for landscapes too. Most landscapes shots require a strong foreground, but it's occassionally fun to create a flat, almost minimalist composition with a long focal length. Minimalism requires a lack of distracting bits and pieces, which is exactly what a telephoto lens provides.
3) Viewer Detachment. There's no doubt that you feel less part of the scene when looking at a telephoto image. You don't have that sense of being enveloped by the foreground, or of the scene continuing dynamically beyond the frame. So it's less vibrant, spontaneous and alive.
But what you gain is a sense of detachment and quiet observation. You're given a clear, uninterrupted view of the subject and can study it in close detail. This lends a real intimacy to portrait photos taken with a large focal length.
I hope this has helped you think about the way focal length influences the style and quality of photos in more than just technical ways. It plays a part in shaping emotion, dynamism, involvement, depth perception, linear structure and mood.
What do you like most about using telephoto/wide angle/standard lenses? Share away in the comments...