Welcome to part 3 of learn photography series, today we are going to explore most important technical aspect of photography, which is “Exposure”
But before we learn about exposure, lets see how the digital cameras work. Basically cameras work similar to human eyes in all aspects. But believe me, our eyes are the best cameras exist in the world. Technology is trying hard to reach that limit though.
We all know any object we want to photograph has to be illuminated, just like our eyes needs certain amount of light falling on the subject in order for us to see them. Light reflects from the subject’s body and passes through lens before it reaches the camera sensor inside the camera just like our retina communicating to our brains about the object we are looking at) . In order to have good picture, there needs to be right quantity of light falling on the sensor, when it does we say picture has “Proper Exposure”.
If less than required light is processed while taking a picture we call that picture “Under Exposed”, too much light we call them “Over Exposed”. Both are undesirable. Although some situations purposely pictures are under or over exposed purposefully.
Simple? Yes… Generally we need almost same “quantity” of light falling on our camera sensor for any type of photography in general. That means it doesn’t matter if you are shooting sport, portrait or a landscape or if you are shooting during day or night. We need almost same quantity of light. Simple …? Yes.. Good!
But … now the problem… when your subject is lit by bright sunlight you may have enough light falling on your sensor, what about cloudy day? there is not sun, so naturally less light is reflected from your subject into the sensor. What about artificial light or a candle light? Now we have very less light… but to produce proper picture we need to accumulate more light on the sensor. How to produce this more light?
In order to achieve “Proper exposure” we need a way to control the flow of light(Please note we still need almost same quantity of light falling on to our sensor). We have three important components to control or manipulate exposure in photography.
- Shutter speed: It’s basically a door/window which opens and closes inside the camera, thereby controlling the flow of light. Faster shutter speed allows less light and slower shutters speeds allow more. Faster shutter speeds produce less blurred pictures, because by the time shutter opened and closed subject is almost at same place (even if the subject actually is moving). On the contrary long exposures are done when available light is less and used specifically to capture city lights or landscapes at night time . (Check the examples at the bottom)
- Aperture: A hole or a opening inside the lens, which can restrict the flow of light by either making the opening too narrow or opening fully just like pupil in our eyes adjusting to ambient light. Aperture also serves other useful purposes too. When the aperture is set wide open, it blurs the background of your subject. This way your subject isolated from the background and looks better. This is what being done by portrait photographers. On the other hand very small aperture produces your subject and the background almost sharp, this is what landscape photographers do. They need everything in the photo to be sharp. Apertures mentioned in “f” numbers, small number f1.4 means bigger opening and f16 is small opening. (Check the examples at the bottom)
- ISO: Basically a number which defines the quality of the image. Small ISO number produces better quality picture. By bumping the ISO we can fool the camera so that camera thinks that more light has been allowed than actually it is. This results in camera giving you better shutter speed or aperture with the expense of sacrificed image quality. (Check the examples at the bottom)
We need to use above three tools to control our picture. Simple? yes..but then why is photography is a complex topic? why cameras have so many controls and complex settings? …read below..
Assume that you are shooting a sport action, things are moving very fast, in a bright sunny day in a open ground. Now you will use higher (faster) shutter speeds so that you will not have motion blurred picture. (If your shutter speed is slow, then by the time your shutter opened and closed, the player would have moved to new position! Camera will record his continuous motion and producing blurred picture). Now assume that it suddenly gets cloudy and still you want to shoot the action. Because you have less light in the field, there is a chance that picture will get darker (under exposed). But you need to keep the same shutter speed (because your subject is still moving) as before but have to increase the light flow.. how? …you will open your aperture so that the opening gets bigger, thereby allowing more light into the sensor. Now you have a proper exposure… Problem solved..yes?… but only till it starts getting real dark, as sun sets if the play still continues, you keep opening your aperture and reach the maximum allowed aperture! Now what?… you start seeing your pictures getting dark again… ! Now you start bumping up the ISO number, basically will are reducing the light sensitivity of your sensor, telling the sensor, not to worry about the quality of the picture, but to give you the shutter speed you wanted… So now you continue to take picture even though there is actual shortage of light. As you keep increasing your ISO you start seeing your images getting grainy (called digital noise). As you reach maximum tolerable ISO, things gets nasty to control. You might try to use the camera flash, but with flash you can shoot only up to certain distance. You have seen those sport photographers shooting excellent shots at night games? yes that’s where expensive camera and lenses shine. Because the special expensive lenses have very wide apertures and high quality sensors also help them.
Photography is basically juggle of shutter speed, aperture and ISO, to keep exposure in control. All cameras have automatic exposure control where your camera decides about the shutter spreed, aperture and ISO settings and give you acceptable picture. But it wont know whether you are shooting a fast action or a city lights. So generally you may have blurred image if you shoot fast action or a darker under exposed image if you try to shoot city lights using this automatic exposure control. To overcome this problem you have semi auto modes in dedicated cameras, where you will fix either shutter speed or aperture to predefined value and ask the camera to set the other settings for you. This way you are guaranteed to get desired results without blurred pictures. I recommend newbies to use the semi auto modes always if you have a camera which allows you to do so. In full auto modes you will learn nothing! its as good as mobile phone camera.
Also cameras have full manual settings where you could control all settings manually. This is what creative photography shines. But his is a advanced topic we will not discuss about them here for now.
Hope I am able to explain what is exposure and how its controlled using dedicated cameras. Mobile photographers, sorry you may not be able to capitalize on semi automatic modes as explained above. But most mobile phone cameras have settings such as “Sport”, “Night Sky” etc which basically does the work of semi automatic modes. Whatever the camera you use you still need to understand the basics of control of lights. Photography is nothing but capturing light at different lighting conditions.
Well you heard the theory, now the practicals. Please check the below pictures carefully and check the explanation below on the settings and modes used. Let me know if you have question or need more explanation on any of the examples below. Its very important that you understand why particular setting is used.
Above picture taken with aperture f 5.6 (maximum possible from my lens), ISO 100 (tried to get best quality), 1/20 sec (low shutter speed as I wanted to allow more light as possible. At this low shutter speed you MUST use a tripod, I know moon does not shake but the cameraman will when he is clicking at that low shutter speed.) (Shutter Priority)
Here I am trying to capture the steaming coffee, subject is stationery, ISO 800, aperture at f 9, important thing to note is the low shutter speed it was intentionally managed at 1/25 sec. This is done to capture the motion blur produced by the raising steam. (Shutter Speed Priority)
Example of shooting action shot in low light, large ISO 1600 was used hence the quality of the picture is not that great, aperture f10 to get complete net and the person in focus, high shutter speed 1/1600 sec is to freeze the motion. (Shutter speed priority)
High ISO of 1000 to trick the camera to allow more light, aperture maximum open at f-5.6, high shutter speed of 1/500 sec to make sure the motion of bubbles are frozen. (Shutter Speed Priority)
Again low light condition, so ISO 800 used, maximum aperture of f 4.5, and slower shutter speed of 1/60 sec used. Note this is hand held shot. I had to take this shot carefully without any camera shake during clicking. (Aperture Priority Mode)
High speed action shot, in a good lighting condition so ISO 400, aperture f 11 because wanted to make sure the complete bird in sharp focus, high shutter speed of 1/1250 sec to freeze the motion. (Shutter Priority mode)
In this example important thing to note is aperture of f16 (most narrow) used intentionally to get that sun flare (star like thing on the sun-rays) rest all the settings managed by the camera automatically. ISO 400, f 16, 1/80 (Aperture Priority Mode)
This is the typical city lights shot I mentioned above. Very low light conditions so used ISO 800, aperture is fixed at f 8.0, camera on Aperture Priority mode, shutter speed automatically chosen by the camera was low at 0.4 sec. Camera was put on steady object to avoid camera shake.
- Post one or two pictures, keeping today’s topic of “exposure” in mind. Also think about the previous chapters you took part too. (I recommend fresh pictures if possible, but old pictures also fine!)
- Let me know type of camera(mobile, dslr, point and shoot)
- Try to put exif data (shutter speed, aperture, ISO) so that I can comment better unless you shot the picture on mobile phone.
- Add a tag ‘XDrivePhoto’
- Add a ping back to this post. (Basically copy the URL of this post, and paste to your post. (Anywhere)
- Title the post as “XDrive Photo Lesson 3 – Exposure”
Your ping-backs may not appear immediately as I have to enable them later. I will check your post and I will comment on your post itself. I will post selected interesting images from you here so that others can also see and learn from them.
Although these lessons are geared towards newbies, expert photographers also welcomed hearty. I need to learn too! There are no teachers here everyone is learning.
Cheers and Happy clicking!
Requesting all my followers to go to these posts and read them and I have my comments in those posts. Its very important you read them as they are practical examples from different photography brains. Any clarifications post a question in my comments section below so that I get notified and will interact with you.
Another great contribution from Helen based on our discussions. Please check this post https://helenchen.ws/2017/07/23/temptation-vs-discipline-cropping-exercises/