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PROFESSIONAL PHOTOGRAPHY TIPS AND TECHNIQUES
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Photo "Quick Tip" #17:
MEGAPIXELS EXPLAINED
MEGAPIXELS EXPLAINED
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Article by Nathan Anderson FreePhotoCourse.com Staff Writer/Photographer all rights reserved What on earth is a “MegaPixel”??? We probably get this question more than any other, in relation to its importance in the overall decision to purchase a new camera. In the second part of this article, I have some very important and sound advice for anyone considering purchasing a new camera, but wondering about the importance of megapixels. But before I get too far ahead of myself, let's get a basic understanding of what these things are and why they are important. Megapixels are part of a component that is so fundamental to any digital camera, that anybody who is 'into photography' should really have at least a basic idea of what they are. Roll-back the time machine many years to a point when digital cameras did not exist. Maybe this sounds familiar... |
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It was Christmas day - Dad got the camera out of the closet, dusted it off and carefully captured twenty-four heart-warming pictures of the family opening presents, friends and relatives gathering to toast the season and everyone seated around the formal table enjoying a huge feast. Disappointingly, at the end of the day Dad realized that there was no film in the camera.
"...with today's digital cameras, there is an electronic version of
film. It is called the 'Image Sensor'”.
I'm sure this happened to many a family over countless holidays, birthdays and special events. In traditional photography, if you don't load the camera with film, it really won't matter how well you use the camera, because there is nothing to record the images. In much the same way, with today's digital cameras there is an electronic version of film. It is called the “Image Sensor”. Traditional film uses chemistry to convert light into a visible and permanent image. A digital camera's image sensor replaces film and, instead, converts light into tiny electrical charges - in effect, data that represents the picture.
How does an image sensor do this? To simplify the idea, think about any device around your home that automatically turns on or shuts off, based on the sun's setting or rising. Night lights, home security lighting, street lights and many other devices use photo-cells (also called photovoltaic cells) that convert daylight into an electrical charge. That electrical charge is used to perform a switch-like function, so that the street light, for instance, switches off as soon as the sun rises.
Increasingly popular electricity-producing solar panels for rooftops and as installed in solar farms, use almost identical technology, but because of their size, produce electric current as opposed to a tiny electric charge. The basic idea is that light is converted to electricity. Metal oxides from elements such as germanium, silicon and selenium are used, as they can be manipulated to create energy from light.
"...with today's digital cameras, there is an electronic version of
film. It is called the 'Image Sensor'”.
I'm sure this happened to many a family over countless holidays, birthdays and special events. In traditional photography, if you don't load the camera with film, it really won't matter how well you use the camera, because there is nothing to record the images. In much the same way, with today's digital cameras there is an electronic version of film. It is called the “Image Sensor”. Traditional film uses chemistry to convert light into a visible and permanent image. A digital camera's image sensor replaces film and, instead, converts light into tiny electrical charges - in effect, data that represents the picture.
How does an image sensor do this? To simplify the idea, think about any device around your home that automatically turns on or shuts off, based on the sun's setting or rising. Night lights, home security lighting, street lights and many other devices use photo-cells (also called photovoltaic cells) that convert daylight into an electrical charge. That electrical charge is used to perform a switch-like function, so that the street light, for instance, switches off as soon as the sun rises.
Increasingly popular electricity-producing solar panels for rooftops and as installed in solar farms, use almost identical technology, but because of their size, produce electric current as opposed to a tiny electric charge. The basic idea is that light is converted to electricity. Metal oxides from elements such as germanium, silicon and selenium are used, as they can be manipulated to create energy from light.
 Example of a CMOS chip from a digital camera This semiconductor converts light from a focused image into millions of electric charges, each representing and mapped to a specific location of the recorded picture. |
The image sensor in a digital camera does the same thing. However, rather than being set-up in large chunks, the light-sensitive materials on a camera's light sensor are printed in a complex array of microscopically tiny specks. These specks are called "Picture Elements" or "Photosites", but people casually call them pixels. Here's where the term "MegaPixel" comes into play. Mega is a prefix that means "million". So if an image sensor chip contains 14,000,000 (fourteen million) of these tiny light-sensitive dots, it is said to be a 14 MP (MegaPixel) chip. Specifically, most cameras use "CMOS" chips, which is an acronym for "Complimentary Metal Oxide Semiconductor". |
BUT HOW ARE THESE MEGAPIXELS CONVERTED INTO AN IMAGE?
If you had the unfortunate experience of creating pointillism artwork in grade school, you learned how to make a picture using nothing but dots. As you spent what seemed to be countless hours putting dots on a piece of paper while your teacher likely used the break to catch-up on some marking, you learned that too few dots resulted in an unrecognizable image, while more dots produced a more recognizable and clearer picture. The same is basically true with MegaPixels. The more picture element dots on a camera chip; the clearer the picture will be.
An 18.6 MP chip has dimensions of 4992 pixels along the horizontal x 3744 pixels along the vertical. Multiply the two and you have the total area; 18,690,048 pixels. That is how many dots will be used to create your picture.
You already know that your camera lens will focus and project an image into the camera body. When that light image splashes against the CMOS chip, different parts of the image will cover different pixels in the same relative areas. Those pixels create individual electric charges which are mapped, processed and saved as a digital file that can be "read" and viewed as a picture image.
BOTTOM LINE:
MegaPixels? It is basically a very advanced form of pointillism - that is, making a picture from dots.
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