Photography 101: The Fundamentals of Light

Photographer Wenjie Zhang introduces exposure and three elements of photography: shutter speed, aperture, and ISO.

Image by Wenjie Zhang

We’ve talked about the philosophy of photography and offered a two-part overview of the craft, and now we’re ready to dig deeper. As Ming Thein discussed in his posts, light is crucial to this process. No light, no photograph.

Wenjie Zhang, the photographer at A Certain Slant of Light, is passionate about architecture, landscape, still life, and travel photography. Here in part one, Wenjie introduces exposure and three elements: shutter speed, aperture, and ISO. Next week, he’ll wrap up our light lesson and discuss the quality and direction of light, and more. Much of what’s covered below applies to those of you with SLRs and dSLRs and cameras with manual modes, but we’ll sprinkle in tips for those with cameraphones and point-and-shoot cameras, too.

Introducing Light

At the heart of every photo is a story, and like ink and paper, many elements come together to tell that story. One of these key ingredients is light. Whether it sets the mood, creates depth, or highlights a subject, the light around you and how you respond to it can often make or break a photo.

The fundamentals of seeing light:

Exposure: The amount of light captured in a photograph, and how to control it.

Quality: How “soft” or “hard” the light is, and the difference between “warm” and “cool” light.

Direction: The position of the light source relative to the scene.

Shadows and highlights: The darkest and brightest regions in a photo, where details become obscured.


Exposure is essentially the amount of light that falls on film or the sensor of your camera, resulting in the overall lightness or darkness of a photo. It is common to hear exposures being discussed using stops, or exposure values (EV). On modern cameras, you’ll see a scale that reflects these values, typically over 6 to 9 stops, with 0 EV being the balanced value as judged by the camera. The difference between each stop is pretty noticeable, if you look at this sequence of the ArtScience Museum:


ArtScience Museum, from -3 EV to 3 EV.

Exposure is controlled by the “holy trinity” of photography: shutter speed, aperture, and ISO speed.

Shutter Speed

Shutter speed is the length of time the shutter of the camera remains open. All other factors constant, the longer this is, the more light is captured, and the blurrier moving subjects become. While walking on the streets of Shibuya, Tokyo, the brightly lit signboards and the bustling crowds caught my eye. To capture the buzz, I used a shutter speed of 1/10s, and the sense of movement in front of the signboards became pronounced.

Shibuya street scene. f6.3, ISO 200, 1/10 sec.


Aperture is the size of the hole of the lens through which light travels, and is measured in f-stops. When the aperture opens up (lower f-stops: f1.4, f2, f2.8, f4), more light enters the camera, resulting in more light being captured. When it’s reduced (higher f-stops: f16, f22, f32), less light enters. More importantly, aperture also affects how blurred or sharp certain areas of the photo are, also known as the depth of field.

For a uniformly sharp image — especially in shots of landscapes or architecture — a higher f-stop is used. This keeps both the foreground and background of the image in focus. However, because the aperture is reduced, you’ll require a much longer shutter speed to capture the same amount of light, so that your photo does not get too dark.

Consider the picture of the Sydney Harbor Bridge below. Because I’d wanted to keep both the bridge and the Opera House in focus, I used an aperture value of f16. As a result, the shutter had to be left open for 15 seconds to achieve a good exposure:

Milsons Point. f16, ISO 100, 15 sec.

At this point, you may be wondering why anybody would use the lower f-stops. After all, sharpness in an image is always welcome. Lower f-stops are useful when you’d like to isolate the subject from everything else. This results in “buttery” images you may have seen before, like the shot below. And because the aperture is increased, less light is required to achieve a balanced exposure, making lower f-stops very useful in low-light situations.

In the picture below of the golden ceremonial crown, using a f2.8 aperture causes the surrounding details of the figurine to be blurred in an aesthetically pleasing way. As an added bonus, the light reflected off the crown creates interesting circles, also known as specular highlights, which typically are associated with lower f-stops:

Peranakan Ceremonial Crown. f2.8, ISO 800, 1/40 sec.

Cameraphone users: You may notice that popular photo apps mimic the blur effect described above. Experiment with Instagram’s tilt shift tool, which forces the focus of an image and a shallow depth of field.

Point-and-shooters: In online photo editors like PicMonkey and Pixlr, you can experiment with blurring and forced focusing in post-production with various smudge, brush, haze, and other effects.


The last member of the trinity is ISO, or light sensitivity. With all other factors constant, a low sensitivity (ISO 100 to 800) results in darker images, while higher sensitivities (ISO 3200 onwards) result in brighter images. High ISO pictures are often “noisy,” in that they become grainy or contain discoloration. As a rule of thumb, ISO is set to the lowest possible value that can achieve the desired shutter speed and aperture.

Putting it all together

Now that you have an understanding of the trinity, let’s put everything together! The exposure of an image is a combination of shutter speed, aperture, and ISO. Unfortunately, there’s no single correct combination that guarantees the perfect exposure, and behind every photographer’s image is a carefully calibrated balance between the three.

Tips for getting the right (or desired) exposure:

It requires discipline. Always plan your shot and what you want to convey.

Decide on a setting. It helps to first decide on a primary setting, whether it is shutter speed (for movement) or aperture (for depth of field).

Experiment. Then, experiment with the other two elements of the trinity to see how the photo changes. In the example below, the shot is underexposed at -1 EV, and we can either (a) opt for a longer shutter speed or (b) use a lower f-stop or (c) use a higher ISO, at the expense of image quality.

Underexposed by one stop.

Over time, balancing this trinity will become easier, leaving you to focus on the other aspects of photography.

Get outside and start shooting!

Here are a few simple exercises to put these techniques to use:

For those with (d)SLRs and cameras with a manual mode: Put your camera into manual mode and select any ISO. Set the aperture (the f-stop) to f4, f8, and then f16. At each setting, adjust the shutter speed until you get the correct exposure. What relationship do you see?


Now, set your aperture to f8, and adjust your shutter speed to 1/15 sec, 1/8 sec, and 1/4 sec. What exposure readings are you getting? Why?


Exercises for all cameras, including cameraphones, from The Daily Post editors:

Consider apps that mimic these effects. Apps like Slow Shutter Cam for the iPhone or Camera FV-5 and other “slow shutter” apps for the Android add dSLR-like manual controls to your cameraphone. To capture movement, other apps like Fast Camera shoot a sequence of photos the instant you launch the app — imitating an SLR’s ability to “freeze” motion.
Play around with the focus. On some cameraphones, you can achieve an out-of-focus photo by placing an object super-close to your lens, which may create blurry, unexpected, yet interesting images. You can often focus on something by tapping it on the screen, too — experiment with the focal point and see what kinds of effects you can create.

Next week, we’ll continue talking about light — from quality and direction, to shadows and highlights.

About Wenjie Zhang
I bought my first DSLR in January 2009, and have not looked back since. I have moved on to a full frame camera, and have the assorted backaches to show for it. My favorite subjects are typically landscapes, architecture and close-ups — basically well-behaved things that won’t develop the tendency to give me the middle finger (Charlie Chaplin mime, Rome, don’t ask). My job keeps me chained indoor most of the time, where I tap on the keyboard all day and work on developing the fairest complexion known to humankind. Since I don’t get go on photo trips and experiment as much as I would like to, my blog has evolved from lofty aspirations into a travelogue of sorts.

Previous posts in our Photography 101 series:

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  1. I find it so interesting how the light can change the tone of the photograph. While on a recent Caribbean cruise I got several photos of the ocean and of course, depending on the amount of light their was a unique tint to the water. This was also true when taking photos of the sunrise with the ocean as the backdrop.


    1. By the way Cheri, you mentioned possibly doing a post about why people don;t answer polls in posts. Did you ever get a chance to do that? I have been casually looking, but if you did i would love to read your opinion.


  2. Reblogged this on ZAM PHOTO and commented:
    This is a great introduction to how light is used and measured in a photo and how that affects creative decision when composing a photograph. If you are just starting out in photography and trying to really understand the differences between shutter speed, aperture, and ISO, this would be a good article to read!


  3. I am so trying to get better at this. I have an inexpensive camera and have never done much photography. I have started a home business on web store and etsy and cannot get pictures as I would like for my products. I have tried all manner of ways and settings. My house has no extra room to set up a light box or such. there is always shadow or wash out. Outside where I live would be a hassle to do also. I spent 3 hours today trying everything and am frustrated. This is another great post on this subject though, my house and camera will not cooperate!


    1. Hi there! For product photography, I find that indoor shots are much easier to set up. You’ll ideally want to set up beside a window, where the lighting doesn’t change constantly. A tripod will also help immensely with getting your camera stable. Or just find a nice solid surface to rest the camera.This will at least make it easier to focus on getting your exposure right.

      For point-and-shoot cameras, the most important thing it where you meter against. The default is usually at the middle of your image, or where you are focusing on (the tiny square that lights up when you half-press). Experiment to see how the effect changes when you focus/ meter on different parts of your object!


  4. learning photography art is the hope to be able to produce outstanding work. always try and learn how to produce the best work is a step to success. info enriching and inspiring to produce achievement. thank you


  5. This is a fantastic explanation of things I’ve been experimenting with, knowing I like the results on some shots but not knowing why. Keep on posting more of these!


  6. Reblogged this on Day One and commented:
    Thank you so much for this post, it is EXACTLY what I have been looking for! Idiots guide to my camera settings in plain English that even a dyslexic like me can follow! I have recently been given a ‘bridge camera’ which has lots of brilliant auto settings, but can also be set manually. So far the auto comes out with much better photos than I can manage with the manual settings and to be honest I am just getting to grips with the camera’s capabilities and idiosyncrasies however I really want to learn how to deliberately create photos like your Shibuya Street rather than accidentally manage a photo such as my Bee and Poppy photo!

    I will print out your post and take it with me in my camera bag on my next outing…..

    Watch this space!!Add your thoughts here… (optional)


    1. The bridge cameras are exciting- That’s how I started to get hooked on DSLRs. Some experimenting in the “creative” modes can go a very long way.


      1. I have wanted a DSLR for ages, but know so little about the settings it seemed silly. My Bridge takes wonderful photos & has as you say some great presets & creative effects, plus several manual options so really a good place to start!


      2. You made a wise choice – a full blown DSLR is a heavy investment in terms of cost and convenience. Far better to wait until you are certain. Camera technology is changing fast, and DSLRs now come in smaller variants. Who knows what will be available in a few years.


  7. Great write-up! I’m a Basic Photography student here in the Philippines and this really helped me review and reaffirm my learning for the first part of my term. Thank you!


  8. Thank you for the awesome recommendations for PicMonkey and Pixlr! I had never heard of them before, but I just tried them out and I think they’re going to be my new addiction!


  9. I am still confused about aperture. If a lower f-stop lets in more light, logic suggests to me that this would create a greater depth of field, but I have read here and other sources that the higher f-stops provide the greater depth of field. What am I not understanding? Can someone help this novice photographer understand? I should add that I like a shallow depth of field, but I always get mixed up, thinking that I need a higher f-stop (less light entering). Only some experimenting is helping me understand.
    This photography 101 is an excellent idea. I am enjoying it immensely.


    1. Hi there Patricia, frankly, I think it’ll be easier to just forget about the technical terms! Ha. To get all-round sharpness, use a higher F-number (f8, f11, f22 etc), To get the blurred/ isolation effect, use a lower F-number (f2.8 etc). I’ve steered way clear of “shallow” vs “deep” depth of field definitions, because I find nothing beats looking at the final image in your camera to understand how aperture works.


      1. It was kind of you to take the time to reply. Thank you. I think you are right in that looking at the final image will be the best way to learn.


  10. Very helpful summary, thanks. I hope you don’t mind if I pin it? I can only use a point and shoot due to the weight of lenses and weak hands, but I have found you can still play with depth of field and get a nice blurry background. Instead of getting close to a small subject, a leaf for example, back off and use max zoom.


  11. I studied photography at college and one of the key topics was working with light. A lot of people think if you push the button the camera will do the rest, but if you really understand the use of light you will push your creative limits more than you thought you could. Manual settings is ways recommended to achieve the best results.