Digital Vs. Optical Zoom

When buying a digital camera in today's market one of the important factors that you will undoubtedly be looking at the power of the zoom function. Unfortunately people who are not so experienced in this field are starting to be a little mislead. Manufacturers are claiming a zoom function called digital zoom, or they are adding up the total zoom of their optical zoom and digital zoom for a total zoom function. This however is a little unfair on the consumer as you will begin to see in this article.

What is Optical Zoom

Optical zoom is what I like to call true zoom. This function of a camera uses the lens within the camera to draw the image closer. Using the optics of the camera the image is bought forward much the same way as binoculars and other such instruments. When using optical zoom quality remains the same and the full resolution of the camera can be used on the zoomed image. Different levels of optical zoom can be achieved by changing the distances between the lens'. The motion of the front lens moving outwards on a camera is the lens achieving a greater level of zoom. The rating of optical zoom on a camera is measured like 2x 4x 8x etc. bringing the image 2x 4x and 8x closer respectively. The best cameras have a high level of optical zoom.

What is Digital Zoom

Digital zoom on the other hand is not a true form of a zoom function. The image itself doesn't actually come any closer as the optics in the camera stay the same. The way the digital zoom works is much the same way as it does on your PC at home. The idea behind digital zoom is that it takes a portion of the image and expand that image to the full size of the picture. What happens here is that the section of image that you are looking at becomes bigger, not closer. The image does look closer because it has been expanded however all that has happened is that the image quality has been reduced because it has been expanded with no new data for the image.
There is nothing digital zoom can do that you can't do on any standard art package at home. You may as well take the picture like you would a normal camera and then alter the zoom to exactly the way you want it at home. It will be no better or worse doing it this way that it would using a digital zoom function.

Why use Digital Zoom

So why would you ever want a digital zoom? Well there are some occasions when this may be useful. Firstly for those of you who don't like computers or are unsure about using photo editing software then the digital zoom function will enable you to get an accurate shot of the specific area you wish to photograph.
The second reason may be that you don't wish to print the pictures out. If this is the case then the digital zoom may not affect your image quality as much as a it would on a printed image. One final reason for digital zoom is that you may be able to see what the subject is doing through the camera a little easier while looking at the screen through digital zoom. Unfortunately with digital zoom, what you see on the screen is usually a little better quality than the final image. Using a camera with a greater megapixel rating and using the camera at its full rating will help when using the digital zoom function as the quality starts off very high so the reduced quality image will still be acceptable.

What is Smart Zoom?
Smart Zoom is a concept designed by Sony. Smart zoom is an intelligent version of digital zoom, the basic principal behind it is that it actively reduces the size (megapixels) of the picture to make more zoom available on the camera without degrading the picture quality. For example if you have a 10 megapixel camera with smart zoom you would be given the option to reduce it to anything below 10 megapixels, smart zoom would then allow the camera to digitally zoom in. Because you set the smart zoom level you control the size of the picture. Smart zoom unlike standard digital zoom will not degrade the quality of the picture. It should be noted that while smart zoom is a useful feature it in no way compensates for having a camera with good optical zoom. Other forms of smart zoom are available from other manufacturers, they are often called similar things such as intelligent zoom or safe zoom. They all act in a very similar manner allowing you to zoom in on a shot using digital zoom without lowering picture. Smart zooms are more effective on cameras with large megapixel ratings as they have more scope to reduce the amount of pixels in a shot without making the picture too small.

What is Total Zoom?

You should watch out for the manufacturers who advertise the total zoom. Although these camera's have an optical zoom function its only part of the total and you should research the camera more thoroughly to get the optical zoom value. Total zoom is calculated by multiplying the cameras optical zoom by its digital zoom. For example a camera that has a total zoom of 30x may have 5x optical zoom and 6x digital zoom, It may also be rated with 2x optical zoom and 15x digital zoom. More research into the camera should be taken when buying one advertised as total zoom. Always check the split between digital and optical when you see a camera with a total zoom rating.



Simply we can say
  
Digital zoom

• Digital zoom is basically a digital crop within the camera. It is not a true magnification. When you use digital zoom you are effectively only capturing part of an image, with lower resolution than the full frame image would have.


• Optical zoom
  Optical zoom is magnification created by a lens. This type of magnification is a "true zoom" and should not adversely affect image quality. Optical zoom should be your first choice for magnification whenever possible.