Friday, July 25, 2008

The Most Important Things to Know About Photography : Focal Length = Angle

Starting In Photography?

After I told a good friend of mine that I'd bought a new camera, he said that he was keen to buy a "proper camera" and try to take some decent photos. He told me that he assumed just buying an expensive camera and using it in Auto mode would probably produce better pictures than a point-and-shoot (which is true) but that to get really good photos you probably have to learn all kinds of photography concepts (also true) and that there was so much stuff to learn that it was hard to know where to start (true again).

So, to help him out, and anyone else who wants to enter amateur photography, I'm going to share my tips for where to get started if you know almost nothing about photography other than how to use a point-and-shoot camera. You won't become a pro by the reading my thoughts (durh!), but you should feel less like a dunce, and you'll hopefully have an idea of what things you might want to do.

Focal Length, Aperture, Shutter Speed

I think these are the three most important things about photography, so it seems sensible to explain them first because it will make other things easier to explain.

We'll look at focal length first.

Focal Length = Angle

I'm writing about "The Most Important Things to Know About Photography", and Focal Length is the first property of your camera that I want to draw your attention.

In photography, 'focal length' is a property of the lens you are using that determines what angle of the scene in front of the camera will be captured in your picture. Basically:

  • The smaller (or "shorter") the focal length, the wider the angle.
  • The larger (or "longer") the focal length, the more narrow the angle.

Some lenses only have a single focal length, and these are called "prime" lenses. Most people are familiar with lenses that have a range of focal lengths, which are called "zoom" lenses. When you adjust the "zoom" on a point-and-shoot camera, i.e. you zoom in or you zoom out, what you are actually doing is changing the lens' focal length, decreasing the focal length when you zoom out and increasing it when you zoom in.

Being able to choose the focal length to use in a photograph allows the photographer to change how much of the subject or subjects will be in the frame. If they were shooting a wide, sweeping landscape, they would most likely use a short focal length (small number, wide angle) so that could capture as much of the "expansive" feel of the land as possible. However, if they were trying to capture a close-up photograph of someone on the other side of a large room, they would need to use a long focal length (larger number, narrow angle).

Focal Length Categories

Focal lengths are typically broken into the categories: Wide, Standard and Telephoto, with some adding Ultra-Wide and Super-Telephoto.

The "Standard" range is so called because it is similar in angle to what our eyes would normally see when looking at a scene.

"Wide", which is smaller focal lengths than "Standard", means a wider angle than we can see without moving our eyes. Wide lenses allow photographers to show their audience, in a single photo, a scene wider than they could see themselves if they were standing in the same place as the camera.

"Telephoto", which is larger focal lengths than standard, means a smaller angle than we would normally see with our eyes, but Telephoto also means the subject will be magnified and so will show details our eyes may not have seen from the same distance.

Ultra-Wide and Super-Telephoto are obviously just extensions of their similarly named compatriates.

So, what are the actual lengths in each category? This is a harder question than it used to be, but I'll keep it simple to start with. If you are using a 35mm film camera or a professional or semi-professional "Full Frame" digital camera (which means it has a sensor the same size as 35mm film), then Standard is around 50mm, Wide is anything less than about 35mm and Telephoto is anything more than about 80mm. However, most people aren't using these cameras.

Sensor Size and Effective Focal Lengths

If you have a more affordable digital SLR camera then everything changes. Because the size of the sensor in your camera is smaller than 35mm film, the angle of view it will capture from a lens with a specific focal length is different. These cameras have a property describing how different the angle is, and this is called the "focal length multiplier".

Assuming your camera has a "focal length multiplier" of 1.6 (most DSLR cameras are either 1.6 or 1.5) then the Standard focal length is about 32mm (as opposed to 50), Wide is anything less than about 22mm and Telephoto is anything higher than about 50mm. I can't explain this any more without getting technical about what the "focal length multiplier" means, and you don't need to know that right now. However, you may go far if you can remember this: the effective focal length of a lens is equal to the actual focal length of the lens multiplied by your camera's focal length multiplier.

Now, the focal length does affect more aspects of your photograph than just the angle, but to keep it simple for the moment it's easiest to remember that you chose the angle your photo will cover by choosing a focal length.

Key Points:

  • Focal Length = Angle
  • Small focal length = "shorter" = wider angle
  • Large focal length = "longer" = more narrow angle
  • Effective focal length = Actual focal length x Focal length multiplier
That's it for Focal Length. Make sure you come back (or subscribe to the feed) to read about more of the Most Important Things to Know About Photography. Next up: Aperture and Shutter Speed.

Copyright (c) 2008 Graham Lea. All rights reserved.

1 comment:

Michelle said...

Cool, I just learnt so much. I will keep an eye out for the next installment!