So you just purchased your first DSLR camera and you have it in your hands. The first question in your mind is probably, “how do I learn to use my camera better?”. Almost anyone can take pictures with a DSLR camera, but to really understand how to take pictures well, one needs to have a good understanding of how their camera works and how to use that to your advantage. There are several different exposure modes you can use, but once you understand how to take pictures using manual mode you will really understand the steps that are involved with taking a high-quality photo. Manual mode is the only way I take pictures, and hopefully in this post I can show you how to do the same thing!
WHAT IS MEANT BY “EXPOSURE”?
To begin to understand how to take pictures in manual mode, you first need to understand what “exposure” is. Exposure is simply how light or dark an image will appear when taken by your camera. Exposure is determined by three things: aperture, shutter speed, and ISO.
Aperture: The unit of measurement that determines the size of the opening of the lens. Measured in “F-stop”. Aperture is inversely related to depth of field. The larger the aperture, the narrower is the range of distance that appears sharp. A larger aperture produces more “bokeh”, or blurriness. A smaller aperture will produce an image where the range of distance that appears sharp is much larger.
Shutter speed: The length of time when the film or digital sensor inside the camera is exposed to light. It is the time the camera’s shutter is open when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. A shutter speed that is too low will produce motion blur.
ISO: This is the sensitivity of your camera’s sensor to available light. A low ISO means your camera’s sensor has a lower sensitivity to light and a higher ISO means your camera’s sensor has a higher sensitivity to light. The higher the ISO however, the more potential for “noise” to be introduced to the image. Generally one wants to shoot at a low ISO (100-200) when possible.
It is the interplay of these three parameters that ultimately determine the “exposure” of the image.
METHODS TO DETERMINE EXPOSURE
Your camera has several available modes in which to take a picture.
Programmed Auto: A mode in which the camera automatically adjusts shutter speed and aperture for optimal exposure. You can however choose other aperture and shutter speed combinations that will produce the same exposure. Best used for snapshots.
Shutter Priority: You choose the shutter speed that you wish to shoot and the camera makes a decision about aperture. Best used for situation where freezing motion is desired.
Aperture Priority: You choose the aperture and the camera makes a decision about the shutter speed. Best used when you want a narrow depth of field.
Manual Mode: This is the mode that gives you complete control. You the photographer choose the aperture and the shutter speed as well as the ISO. Utilize the in-camera meter (or an external light meter) to determine optimal exposure.
Metering is used to measure the brightness of the subject being photographed (how much light is entering the lens and illuminating the camera’s sensor). In the film photography days an in-camera meter did not exist and thus photographers relied on external light meters. These are the most accurate meters available because they measure incident (as opposed to reflective) light. In the digital photography era cameras are equipped with in-camera meters that rely on reflected light from the subject. When a camera meters it samples the amount of light from several areas of the photo, and then calculates what the current exposure of the photo you are about to take is. There are three basic metering modes:
- Matrix (Nikon) or Evaluative (Canon) metering: Light is sampled from all areas of the viewfinder to determine exposure. This is the default metering for digital SLR cameras. This works best when the subject and background are evenly lit. It does not work for backlit photos.
- Center-weighted metering: Light is sampled from a small circular area where the point of focus is located. This does work well for fashion photography so that the subject and clothing can be properly exposed.
- Spot metering: Light is sampled from an even smaller area of the viewfinder to determine exposure. This is the mode I use all the time. The subject is my point of interest, and I want to make sure my subject’s skin is properly exposed. It does not work well if the subject is wearing white (as you may end up over-exposing white clothing). In that case, meter off the clothing, not the skin.
Your in-camera meter can be found in the viewfinder of your camera. You can control the exposure by adjusting ISO, shutter speed, and aperture. It generally looks like this:
By changing the three parameters (ISO, shutter speed and aperture) you can either properly expose, under expose, or over expose your subject. Neither underexposing or over exposing is ideal, so care must be taken to meter correctly to create an image that has been properly exposed. I purposely overexpose by one step, as most skin tones have a tonality that is a brighter gray than middle gray (this is the tone that all in-camera, or reflective, light meters are programmed to read – more on this topic here). Below you can see how a properly exposed image will look, in comparison to an underexposed image or an overexposed image:
SO HOW DO I DETERMINE EXPOSURE?
- Set your aperture of choice – Choose your aperture to achieve the depth of field that you want. I almost always set my aperture at F2 as I love to have a narrow depth of field to place emphasis on my subject (this is how you achieve “bokeh”)>.
- Set your ISO – You should generally try to keep your ISO between 100-200. The lower the ISO the less “noise” you will have in your image. This is easy to do in an outdoor setting with plenty of light. You will likely need to raise your ISO when shooting in a low-light setting such as an indoor setting or at dawn or dusk.
- Set your shutter speed – You change your shutter speed while watching your in-camera meter. Make sure that your photo is properly exposed by watching your in-camera meter to make sure your marker is in the center or slightly in the positive region. Your shutter speed should always be at least 2x your focal length (for a 50 mm lens this should be 1/125th of a second). I shoot most often with the 135f2 lens, so I make sure my shutter speed is at least 1/320th of a second at all times. If your shutter speed is to slow, camera shake will be introduced and your image will be blurry. If your shutter speed falls below the necessary threshold then you will need to raise your ISO until your shutter speed is appropriately fast.
You can also check your camera’s histogram to make sure the exposure of the photo is correct (more on this topic later, but you can read more here now as well).
These are the steps that I do when I am the photographer taking pictures of someone else. When I am the subject, I typically will determine proper exposure by metering off the skin of my assistant (usually my daughter, husband, or one of my colleagues) in the spot where I want to pose. Then we switch places and I pose while my assistant takes the picture. In the event that I am taking the pictures by myself with a remote trigger (which I will often do), I will meter off the sidewalk because the tone of the sidewalk is typically close to skin. I shoot in RAW and will make final exposure adjustments in Lightroom as necessary.
This process may seem daunting at first, but with a little practice you will be a pro in no time. As soon as I discovered how to use my in-camera meter, I never looked back. Now manual mode is the only way I ever take pictures. I want ultimate control, and manual mode is the way to accomplish this.
I have given a lot of information in this post and hopefully you find it helpful. The final thing I will say is if you want to read further on the topic then I highly recommend you read Understanding Exposure by Bryan Peterson. It is the only photography book I have ever read, but it is the most important book available to learn how to take great pictures.