Printed representations
All three images have been resized using Nikon Capture NX and their colour profile converted to sRGB for Internet viewing. Monitor resolution of 72dpi would require an image of 432 x 288 to represent a 6 x 4 photograph which is very small and would provide little value. Printed representations are instead 800 pixels high to cover most readers monitor and would equate to a photograph being nearly 11 inches along the vertical side.
http://www.foxaviationphotography.co...mg0014full.jpg
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http://www.foxaviationphotography.co...mg0018full.jpg
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http://www.foxaviationphotography.co...mg0016full.jpg
Is it possible to judge which is which? - NO!
Therefore anyone wishing to share photographs using the Internet can do so using the most modest of photographic equipment without being bogged down by the complications of megapixels. Printed photographs to approx 6 x 4 at 300dpi can be produced without any real difference.
Extra megapixels are required when printing large images but some claim the advances in bi-cubic resizing permits photographers to produce high quality enlargements from 4Mpx sensors although as seen in the native 500 x 500 crop examples that more megapixels does provide more detail if used without resizing. Extra megapixels are require more memory card and hard disk space, if using a camera to its optimum RAW should be used necessitating a very powerful computer to process and hold in memory a highly complex and large RAW image. In the examples RAW image size were in a range of 3.5 to 10.3MB hence a linear relationship between megapixel count and storage requirement although based on experience a non-linear relationship exists between computer performance and RAW image size, requiring more than three times the power to process a 10.3MB RAW file when compared to 3.5MB output from a 4.1Mpx camera in the same period of time.
So, are megapixels important?
In summary, NO! Megapixels do offer greater scope to select an area of a photograph to crop and provide greater fine detail but often negated when printing standard size photographs and sharing using the Internet. More megapixels require more hard disk capacity to hold for long term storage. Greater processing power is also required if shooting RAW mode and often have greater amount of noise. Lower megapixel sensors gather more light resulting in cleaner images but with less detail but require less storage capacity.