A Short Course Book
Curtin's Guide to Digital Cameras
And Other Photographic Equipment

Composing Images

Monitors show you what the view looks like through the lens.

The best monitors are those that swivel and tilt to any angle.

With a swiveling monitor, you can shoot up at things close to the ground such as this newt.

Because an optical viewfinder is offset from the lens, what you see through the viewfinder (top) is different from the image you actually capture (bottom).

Click to explore how parallax affects your view of a subject.
Electronic viewfinders are small flat-panel displays inside the viewfinder. Courtesy of Zight.

A common monitor icon.

Click to see the light path through a SLR.

SLR viewfinders display focus areas and camera settings.
When choosing a digital camera, one of the first things to decide is whether you want one with both a monitor and viewfinder. Many of the latest small cameras have dropped viewfinders, partly to make more room for a larger monitor. This isn’t an unmixed blessing because the primary roles of these two features are quite different, although there is some overlap. If your camera has no viewfinder, you are forced to compose all of your images using the monitor. This means you have to deal with glare on sunny days and find a way to get sharp images while holding the camera out at arm’s length.


Monitors are small LCD color screens built into most cameras. Their size is specified using the diagonal measurement, in inches. Most have brightness adjustments that you can change manually, or which the camera will adjust automatically. These screens range between 1.5 and 4 inches and serve a number of useful functions:
  • Menus are displayed so you can change camera settings.
  • Image composition. On many, but not all cameras, you can compose the image on the monitor before you take it. The monitor (or electronic viewfinder) displays the scene as it unfolds by feeding images captured by the sensor to the monitor. In effect you are looking at a small TV screen showing the scene as it appears through the camera's lens. This process, common on even the least expensive point and shoot cameras, is called live view or live preview. Most digital SLR cameras don't yet offer live view because of they way they are designed. These cameras use a mirror to bounce the image formed by the lens into an optical viewfinder. Light from the scene only reaches the sensor when you press the shutter button to raise the mirror and open the shutter. To offer live view on one of these cameras two approaches are used:

    In some cameras a second sensor is positioned in the in the viewfinder so it can feed a continuous sequence of images to the monitor. The number of images it sends per second determines how smoothly moving objects are displayed on the monitor. This second sensor also makes it theoretically possible to capture movies, something SLRs can't normally do.

    Another approach used by some cameras is to lock up the mirror and open the shutter when you switch to Live View mode. This allows light from the scene to continuously reach the sensor where it can be captured and fed to the monitor. When you press the shutter button, the shutter closes, the mirror comes down, the sensor is cleared and then the picture is taken.

    Only time if any or all of these features catch on.

  • Image review keeps an image on the screen for a few seconds after you’ve taken it so you can check it. Some cameras let you keep the image on the screen longer so you can perform some or all of the image management functions described below.
  • Playback mode lets you scroll through your images manually, as a selfrunning slide show, or in index view that shows 9 or so small thumbnails at a time.
  • Image management in playback mode let’s you scroll through the images you’ve taken and delete, rotate, rename, print, protect, copy or otherwise manage them. Many cameras also display thumbnails of a group of images in index view so you can quickly locate and select the images you’re looking for. Most also let you enlarge the image on the monitor to zoom in on details in your photo—a great way to check sharpness. A few cameras now have touchsensitive monitors so you can manage your images with a stylus instead of dials and buttons.
  • Histograms are graphs showing the distribution of brightnesses in your image so you can check that the exposure is correct. Most cameras that offer this feature let you view the histogram after capturing a photo but a few let you see the histogram as you compose the image.
  • Direct printing lets you use the monitor to select images for printing when you bypass the computer to print directly from the camera.
  • On-screen editing can be performed on some cameras although editing on a tiny screen using buttons and menus isn’t usually the most enjoyable way to do it. However, it’s useful when printing or sharing directly from the camera.
Landscape mode shows the image horizontally.
Portrait mode shows the image vertically.
On cameras that let you compose the image on the monitor, the displayed image is taken directly from the image sensor, so it is a true TTL (through-the-lens) view. Although you can use the monitor to compose photos, there are times when you may not want to for the following reasons.
  • Battery drain. Large monitors drain batteries quickly, so it’s best to keep them turned off as much as possible and use the optical viewfinder for taking pictures.
  • Glare makes the image on the monitor hard to see in bright sunlight.
  • Steadiness is diminished when you hold the camera at arm’s length. This tends to introduce blur into your images through camera shake.
Although you may want to keep the monitor turned off to conserve battery power, there are a few situations in which it becomes indispensable.
  • Close-ups. When using a camera that isn’t an SLR for close-ups, the monitor is a great way to compose and focus the image since it shows the scene exactly the way it will be in the image you’ll capture. The optical viewfinder doesn’t show the same view because it is offset from the lens.
  • Odd angles. When photographing over a crowd, at ground level, or around a corner, a camera with a tilting and swiveling monitor lets you compose the image without holding the camera up to your eye.
When considering a monitor, here are some things to keep in mind:
  • The monitor gets its image directly from the image sensor so it shows the view seen through the lens (TTL). Most show the entire image.
  • The monitor often shows how light or dark the captured will be. This lets you use the flash or adjust the exposure to make it the way you want it.
  • Tilt and swivel monitors let you shoot from different angles.
  • Screen size and resolution is important not only to evaluate images but to share them with others.
  • A wide viewing angle lets a small group see the photos together.
  • Transparent monitor covers keep monitors from being scratched. They are cheap and easy to replace.
  • Many cameras have connectors and cables for displaying your photos on a TV set or a computer with a TV tuner. You can also connect the camera when taking photos so it displays everything on a much larger screen.
  • A glare-proof surface and brightness adjustment help you see the menu and images in bright sunlight where many monitors just become mirrors.


Viewfinders are ideal for following fast action as it unfolds—waiting for the decisive moment. One of the advantages of some, but not all, of them is that they don’t draw battery power so your batteries last longer. Also, most viewfinders are coupled to the zoom lens and show the same area that will be captured in the photo. There are three kinds of viewfinders and most photographers would consider the SLR viewfinder the best.
  • Optical viewfinders on digital SLR cameras show the scene through the lens (TTL) just as 35mm SLRs do. A mirror bounces light coming through the lens into a prism that directs it out of the viewfinder. When you take a picture, the mirror swings up and the shutter opens to let light hit the image sensor and create the image. These are true “what you see is what you get” viewfinders because you see exactly what the lens sees. Some cameras have interchangeable focus screens so you can adapt the camera for your preferences. For example, if you do architectural or product photography you may want grid lines in the viewfinder so it’s easier to keep things aligned. Some cameras let you add the grid lines digitally by changing a camera setting.
  • Optical viewfinders on point-and-shoot cameras show the scene through a separate window that is slightly offset from the view seen by the lens. The offset view isn’t a problem except in close-up photography where parallax causes you to see a view that is slightly offset from the one the lens sees so a subject centered in the viewfinder won’t be centered in the image.
  • Electronic viewfinders use a small LCD monitor built into the viewfinder to display the same through-the-lens image seen by the image sensor. Many of these cameras let you switch between the monitor and viewfinder and both show exactly the same scene and same information. Because these displays are electronic, menus can be displayed so you can change settings without lowering the camera from your eye. This is especially useful on bright days when a monitor is hard to read because of glare. It’s also advantageous for people who need reading glasses because the menu can be read without glasses if the viewfinder has a diopter adjustment control. The two biggest shortcomings of these viewfinders is their refresh rate and resolution. A slow refresh rate means that as you move the camera, the image on the screen lags behind the scene you are pointing at. When panning, the screen seems to jump between frames. On some cameras the refresh stops when you press the shutter button halfway down to lock focus so the image you capture may be different from the one you see. The low resolution of these viewfinders makes it hard to tell exactly what you are photographing. You don’t see fine details, colors, or tones the way they actually are.
In this cutaway view of a Canon SLR you can see the mirror that bounces light up into a prism for the viewfinder. The mirror swings up out of the way when you take a picture. Courtesy of Canon.
When considering a viewfinder, here are a few things to think about:
  • Most viewfinders don’t show the entire area that will be captured. Usually they show about 95%.
  • Diopter adjustment dials or sliders let you adjust the viewfinder so you can see the image without reading glasses.
  • Eyepiece covers are needed on SLRs to keep light from leaking through the viewfinder when using a self-timer or remote control and you are not blocking the light with your head.
  • When taking close-ups on a point and shoot camera without an electronic viewfinder the viewfinder is offset from the lens so the area seen in the viewfinder will differ from the area included in the image.
  • Optical viewfinders on point and shoot cameras don’t display important shooting information such as focus and exposure settings.

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