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Photography Tips

Introduction to digital photography


Good digital cameras give you more control over your images. They do so by allowing you to control the light and motion in photographs as well as what's sharp and what isn't. Although most digital cameras are fully automatic, some allow you to make minor adjustments that affect your images. The best ones offer a wide range of controls-in some cases more than you'd find on a 35mm SLR. However, regardless of what controls your camera has, the same basic principles are at work inside the camera. Your automatic exposure and focusing systems are having a profound affect on your images. Even with your camera on fully automatic, you can indirectly control, or at least take advantage of the effects these controls have on your images.
All digital cameras have an automatic mode that sets focus, exposure, and white-balance for you. All you have to do is frame the image and push the shutter-release button. You'll find that this auto mode of operation is great in the vast majority of situations because it lets you focus on the subject and not on the camera.
  
Taking a Picture in Automatic Mode - step by step

  1. Turn the camera on and set it to automatic mode. Be sure to remove the lens cap.     Look in your camera manual for a section on selecting automatic exposure and turning the LCD monitor on or off.
  2. Compose the image in the viewfinder making sure the subject that you want sharpest is in the focus area in the center of the viewfinder.
  3. Press the shutter-release button halfway down so the camera can set focus, exposure, and white balance. When the camera has done so, a lamp may glow or the camera may beep. 
  4. Press the shutter-release button all the way down to take the picture. When you do so, the camera may beep. The camera then saves the new image onto the camera's flash card.
  5. When done, turn the camera off.

Tip - To conserve your batteries, turn off the LCD monitor and compose your image through the optical viewfinder.


Technical terms and explanations 

Framing the image
The viewfinder shows you the scene you are going to capture. To zoom the lens to frame your image, press the zoom-out button or lever to widen the angle of view and the zoom-in button or lever to enlarge subjects. If the image in the viewfinder is fuzzy, see if the camera has a diopter adjustment dial you can use to adjust it.

Auto-focus

The area you place in the focus area in the center of the viewfinder is used to determine the sharpest part of the scene. How close you can focus depends on the camera you are using.

Auto-exposure

Programmed auto-exposure measures light reflecting from the scene and uses these readings to set the best possible exposure.

Auto-flash

If the light is too dim, the auto-exposure system will fire the camera's built-in flash to illuminate the scene. If the flash is going to fire, a flash lamp usually glows red when you press the shutter-release button halfway down.

Automatic white balance
The color cast in a photograph is affected by the color of the light illuminating the scene so the camera automatically adjusts color balance to make white objects in the scene look white in the photo.
  
Compression
The size of an image file and the quality of the picture it contains depend in part on the number of pixels in the image and the amount of compression used to store it.

To make large image files smaller and more manageable, digital cameras store images in a format called JPEG pronounced "jay-peg." This file format not only compresses images, it also allows you to specify how much they are compressed. This is a useful feature because there is a trade-off between compression and image quality. Less compression gives you better images so you can make larger prints, but you can't store as many images. More compression lets you store more images and makes the images better for making smaller prints, posting on a Web page, or sending as e-mail attachments. The only problem is that your prints won't be quite as good. For the highest resolution, some cameras offer an uncompressed format.

Image Size
In addition to different compression modes, many cameras let you also change image size as a way of controlling the size of image files. Because you can put more 640 x 480 (VGA) images into a storage device than you can put 1600 x 1200 images, there may be times when you'll want to switch to a smaller size and sacrifice quality for quantity.

Tip - Study your camera manual to find out how to change these image settings : compression - quality - size

MP (Megapixel)
A megapixel (MP) is 1 million pixels, and is a term used not only for the number of pixels in an image, but also to express the number of image sensor elements of digital cameras.
A camera with an array of 2048×1536 sensor elements is commonly said to have "3.1 megapixels" (2048 × 1536 = 3,145,728). The more megapixels you have, the more quality in the photo you take.


Important note!!  
The more megapixels (sensor elements) you squash onto a camera photo-light sensor, the warmer the sensor gets. That is why professional SLR cameras have physically bigger size photo sensors.
The problem with high-megapixel, small sensor elements, is that they overheat in low light conditions, and you get noise on your photos as a result. ( See example of photo with noise below at "Noise" )



Image sensor
An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. The image sensor replaced the film that was used in older cameras.


Photo of image sensor below.























Noise
Grainy photos with randomly scattered coloured pixels that break up smooth areas. This is what's known as noise. 
Example of photo with noise




























Do this at home!                       Read your camera manual on how to do the following steps.  


To take a picture with noise, do the following.
Step 1:             Go to a dimly lit room or wait until it is darkening outside.
Step 2:             Set your camera to a high ISO setting, 800 for example.
Step 3:             Disable the flash.
Step 4:             Set the shutter speed slow enough to allow for good exposure.
Step 5:             Take a photo of something and look at it on your computer.




Aperture
The opening behind the lens that permits light to travel to the camera's interior where the sensor is located. Aperture sizes are measured in full stops (f-stop-number) A f-stop of 22 closes the lens opening more, and a f-stop of 1.4 closes less. Typically, a fast shutter speed will require a larger aperture (small f-stop number) to ensure sufficient light exposure, and a slow shutter speed will require a smaller aperture (larger f-stop number) to avoid excessive exposure.








More technical info
The lens aperture is usually specified as an f-number, the ratio of focal length to effective aperture diameter. A lens typically has a set of marked "f-stops" that the f-number can be set to. A lower f-number denotes a greater aperture opening which allows more light to reach the film or image sensor. The photography term "one f-stop" refers to a factor of √2 (approx. 1.41) change in f-number, which in turn corresponds to a factor of 2 changes in light intensity.


Shutter Speed
The duration, for which the camera's aperture is opened, thereby allowing light to stream in. Longer shutter speeds leave the aperture open longer, letting more light in and resulting in more exposure.




White Balance (extra info)
Human eyes compensate for lighting conditions with different colors of light. A digital camera, however, requires a reference point that represents white. It then calculates all other colors based upon this setting.
Click this link for a good article on white balance

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