Let’s tackle megapixels first. All digital pictures are composed of tiny dots called pixels. A megapixel is roughly one million pixels. The higher number of megapixels in a camera, the more details the camera can capture and reproduce. Obviously, a 3-megapixel camera can produce more details than a 1-megapixel camera. At one time, when we were dealing with 1- and 2- megapixel cameras, this was very important. Now, however, most new digital cameras are greater than 5-megapixel. This is enough megapixels to create clear prints as large as 11” x 14” (28 x 36 cm), and to be able to choose parts of a photo to enlarge and still get good results. This is adequate for most users.
With very high megapixel cameras, the camera captures more information which may be beneficial, especially when printing large pictures or trying to print a portion of the picture. More megapixels means a higher quality and fidelity in the final print. For instance, assuming similar cameras, if you take a picture with a 4-megapixel camera and take the same picture with a 10-megapixel camera when you print them both out as a 4” x 6” print (10 x 15 cm), you will see little difference. However, if you print the same picture in an 11” x 14” (28 x 36 cm) format, the 5-megapixel print will be of good quality, but 10-megapixel print will be better.
You also need to remember that the higher the megapixels, the larger the file size. So if you shoot at the highest megapixel count, your storage medium will fill up more quickly.
In actuality, the thought, “the higher the camera resolution, the better the camera quality” was always a myth. Image quality depends on several other factors, such as the camera lenses and the sensor that captures the image. So let’s get into a few of those, as well.
Type and Size of Sensor
The type and size of the sensor in a digital camera has a great impact on the quality of the pictures. There are two major types of image sensors CCD (charged-couple device) and CMOS (complementary metal-oxide-semiconductor). Most point-and-shoot camera use CCDs. Most SLRs use CMOS because it is easier to make them in larger sizes. Yet, ironically, many cell phones also use CMOS because they consume less power. There are many differences in these two technologies, but the size of the sensor still makes the biggest difference.
A picture taken with a 3-megapixel CMOS camera phone will be poorer quality than one taken with a 3-megapixel CMOS SLR. Speaking in generalities, half of the poorer quality will be due to the inferior lens and other components, and the other half will be due to the small size of the sensor.
Here is a brief simplistic summary. Cameras with smaller sensors use shorter focal length lenses to get the same angular coverage as cameras with larger sensors do with longer focal length lenses. Also, the smaller the sensor, the smaller the megapixels have to be and the more they will be crammed together. This results in grainier photos, especially when taken in low light.
That said, all you have to remember is that when we talk about sensors, bigger is better.
If you want to make the best choice in an SLR digital camera, you will want to fully investigate the full-frame sensor versus the 4/3 sensor that are the competing formats in the SLR area. One is not necessarily better than the other, they are just different. Also be aware that more sensor formats are in the making.
Lens Type
While much of the cameras picture quality is controlled by the resolution and the sensor, a better quality lens will produce a better image.
You seldom have a choice of lenses on a compact camera. Some have zoom lenses and some do not. The advanced digital cameras usually come with a more capable lens, which will have optical zoom and other features like built-in wide-angle capabilities.
The lenses on SLR are interchangeable. In fact, SLR cameras and lenses are often sold separately. The number of available lenses is quite large. Only a certain type of lenses will fit on a certain brand camera. For instance, for the most part, a Canon SLR will use Canon lenses. A Nikon SLR uses Nikon lenses. The Olympus digital SLRs use Zuiko lenses. A few manufacturers like Zeiss, make some lenses with different mounts to accommodate different brands. Lenses are very important in SLR cameras, so before you purchase a digital SLR, you will want to investigate the available lenses.
Digital vs. Optical Zoom
Even if you think you may not need a zoom lens, it is a nice feature in a digital camera that often comes in handy. There are several things to note about zoom lenses. In digital cameras, there are two types of zoom: digital and optical. Many of today’s cameras have both, but this is only done to make them sound better. Optical zoom is a real type of zoom. It uses the camera’s optics to zoom in for a close up producing clear results. Digital zoom is a simulated zoom that is created digitally within the camera. The camera takes a small portion of the image and through a mathematical method of interpolation, resizes the image to a larger size. Since digital zoom reduces the resolution of the image, it produces results that are not as clear as optical zoom. Digital zoom, which requires no moving parts, is much cheaper to add to a camera, but it produces results that are inferior to optical zoom. So it is best to just ignore the digital zoom and focus on the optical zoom when you buy a camera.
