Now before going to the effect of megapixel on photography lets understand what is megapixel .
Megapixel never was a parameter in film camera's right ? yes this is purely a digital camera parameter and it has been hyped and used as a big time marketing strategy for selling the camera be it in a phone or a full fledged camera , If so what is it and what do we need?
Now consider that you draw a 4"*6" rectangle and then you start pouring sand inside (rather spread to cover entire space). Initially they look too granular and spread across but as you fill in and once a layer is formed not matter how much sand you fill inside the space it still will look the same right , that's exactly the job of pixel's on a photograph.
In layman terns pixels are the dots drawn in placed in the resolution of the picture chosen by you.Now that we have known this then what is the use of a higher megapixel camera ? Now take the same sand inside rectangle example , but now make a bigger rectangle say 5"*7" and then spread the same amount of sand (Which was the threshold of 4*6 ie beyond which it did not make difference), Now suddenly it looks grainier right .. so filling some more sand would help.Higher mega pixel have exactly the same benefits.
I have put up a pictorial example below (click on the image to get enlarged view). The left side of the image is 200% scaling(zoom) of a 1600*1200 image and a certain portion is cropped and right side is that of a 640*480 image. When you do this you definitely see that the quality of left side is far better .Below that you can original picture.
Thus if your aim is to put up photos on istock or publish it in magazine or make a huge blow up then go ahead and take picture of higher resolution.But if your goal is to print a 4*6 or 5*7 photos you can set medium resolution.
Now you may ask when i have a better megapixel camera why shouldn't i take a picture of higher resolution, that is because pixels are memory intensive.Now consider you have a SD card of 1GB.Assuming that your camera stores it in RAW format(That is not normally the case , standard is jpeg).Consider a 1600*1200 image , this will take up 1600*1200*24(assuming 24bits per pixel)/8(bits per byte)*10^6 , It will take about 6 MB of space(JPEG would be around 500-800kb). so that would mean you can store about 170 pictures whereas if the resolution was 640*480 it would be about 900kb.(jpeg would be roughtly 50-60kb).which would mean you can store roughly 1100 photos , roughly 6 times more for the higher resolution which you dont need.
Now that you have a 10Mega pixel camera , does all the pictures taken will be at 10Mpixel? No that's not the case if you take a 640 * 480 picture it will be a 0.3 Mega pixel image, The highest image size in you camera would be the maximum pixel supported by the camera. say 3264 * 2448 would be using 8 Megapixel.
Now you can decide for yourself what megapixel image or quality you want based on your requirement.Normally for a magazine or high quality prints you would need 300 pixels per inch so if you are taking a picture at 1600 * 1200 then the best picture you would get is of size 5.3" * 4 " but for a regular home prints it would be 200 pixels per inch with a good quality printers so you can easily get a 8" * 6 "
Calculation to find memory used for raw image :
Resolution is x(width) by y(height) then( x*y*No of bits per pixel) / (8(No of bits per byte) * 10^6) to get in Megabytes
Calculation to find the size required for printing an image :
x/ppi * y/ppi
x is width y is height
pixel per inch (PPI) which can be 300 for high quality 200 for medium quality
Megapixel never was a parameter in film camera's right ? yes this is purely a digital camera parameter and it has been hyped and used as a big time marketing strategy for selling the camera be it in a phone or a full fledged camera , If so what is it and what do we need?
Now consider that you draw a 4"*6" rectangle and then you start pouring sand inside (rather spread to cover entire space). Initially they look too granular and spread across but as you fill in and once a layer is formed not matter how much sand you fill inside the space it still will look the same right , that's exactly the job of pixel's on a photograph.
In layman terns pixels are the dots drawn in placed in the resolution of the picture chosen by you.Now that we have known this then what is the use of a higher megapixel camera ? Now take the same sand inside rectangle example , but now make a bigger rectangle say 5"*7" and then spread the same amount of sand (Which was the threshold of 4*6 ie beyond which it did not make difference), Now suddenly it looks grainier right .. so filling some more sand would help.Higher mega pixel have exactly the same benefits.
I have put up a pictorial example below (click on the image to get enlarged view). The left side of the image is 200% scaling(zoom) of a 1600*1200 image and a certain portion is cropped and right side is that of a 640*480 image. When you do this you definitely see that the quality of left side is far better .Below that you can original picture.
Thus if your aim is to put up photos on istock or publish it in magazine or make a huge blow up then go ahead and take picture of higher resolution.But if your goal is to print a 4*6 or 5*7 photos you can set medium resolution.
Now you may ask when i have a better megapixel camera why shouldn't i take a picture of higher resolution, that is because pixels are memory intensive.Now consider you have a SD card of 1GB.Assuming that your camera stores it in RAW format(That is not normally the case , standard is jpeg).Consider a 1600*1200 image , this will take up 1600*1200*24(assuming 24bits per pixel)/8(bits per byte)*10^6 , It will take about 6 MB of space(JPEG would be around 500-800kb). so that would mean you can store about 170 pictures whereas if the resolution was 640*480 it would be about 900kb.(jpeg would be roughtly 50-60kb).which would mean you can store roughly 1100 photos , roughly 6 times more for the higher resolution which you dont need.
Now that you have a 10Mega pixel camera , does all the pictures taken will be at 10Mpixel? No that's not the case if you take a 640 * 480 picture it will be a 0.3 Mega pixel image, The highest image size in you camera would be the maximum pixel supported by the camera. say 3264 * 2448 would be using 8 Megapixel.
Now you can decide for yourself what megapixel image or quality you want based on your requirement.Normally for a magazine or high quality prints you would need 300 pixels per inch so if you are taking a picture at 1600 * 1200 then the best picture you would get is of size 5.3" * 4 " but for a regular home prints it would be 200 pixels per inch with a good quality printers so you can easily get a 8" * 6 "
Calculation to find memory used for raw image :
Resolution is x(width) by y(height) then( x*y*No of bits per pixel) / (8(No of bits per byte) * 10^6) to get in Megabytes
Calculation to find the size required for printing an image :
x/ppi * y/ppi
x is width y is height
pixel per inch (PPI) which can be 300 for high quality 200 for medium quality
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