The Basics of How a Camera Lens Works

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Lenses and Focusing

This is what lesson 2 of the Photography 101 course that I am following has been looking at. I have found it really interesting because knowing how a lens works and focuses in on a subject, helps me to understand more when things go wrong or wont work how I want them to!

It looks at how light bends or refracts and how it then reacts when traveling through or onto a surface or object. For example if light hits the surface of water at an angle then because one edge of the ray of light has hit the water first it will bend. How much it bends depends on the angle it hit the water in the first place.

Lenses

And that’s how lenses work, by bending the light coming through the lens we can get the light to focus on one point. Depending on how much the lens is able to bend or refract the light, and what angle the light hits the lens.

Focusing

And that’s where focusing comes in. If parallel light hits a lens it will pass through and converge at the same point. But if the light hits the lens at an angle then the lens bends the light to focus on one point. The point at which the light then meets again on the other side of the lens is called the focal point, and that changes depending on how much the light has been bent. The distance from the lens to the focal point is measured in mm which you will recognize from the way different lenses are described.

Now we get to the homework

Every week there is a list of homework choices that you can have a go at, which is great because it helps me to cement in my mind what has been taught in the lesson. So this week I chose to demonstrate the refraction of light by doing the old pencil in a bowl of water experiment.

As you can see in the photos it shows exactly what I have been trying to explain! I always like to see a visual explanation, it’s just easier to understand.

I also noticed that the rim of the bowl that is thicker than the rest of the bowl, refracts the light as well. Which reminds me even more of a lens.

I’m enjoying posting about the course in this way, although it’s not a detailed review of the lesson’s it’s my way of confirming what I have learned. To post and talk about the new knowledge I now have helps me remember it, and using it increases my understanding of it. I hope it helps you too by giving a very simplified view of the excellent lessons in the Photography 101 course.
Mandy

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