Megapixels - An Explanation of Megapixels and How They Affect Photos

Discussion in 'Digital Cameras' started by Abigail1, Oct 17, 2012.

1. Abigail1Guest

Camera manufacturers are fond of advertising cameras by the number o
megapixels they have. But what exactly is a megapixel and how does i
affect photos?

A megapixel is 1 million pixels. Pixels are small squares that are pu
together like pieces of a puzzle or mosaic to create your photographs
The resolution of your image will be determined in large part by ho
many of these tiny squares are packed together in a small space.

An 8 megapixel camera (8MP) would have roughly eight million tin
squares of information per inch while a camera phone at 1.5 megapixel
(1.5MP) would only have one and a half millions squares of informatio
in an inch.

So what does that mean for your photos?
squeezed into an area, the better our eyes blend the edges together t
create a complete image. If too little information is available the ey
will notice the jagged edges of the pixels where they meet, just as yo
see the individual squares of mosaic tile designs. The accepte
"standard" for printing images is currently 300dpi (dots per inch)
While dots per inch aren't technically the same as pixels per inch th
difference won't affect you in your day to day photo taking/printing.

How much information do I need?
To figure out how much information you need for a specific print siz
all you need do is multiply the print size by the resolution desired
For example, with the 300dpi rule in mind, to print an 8x10 photo yo
would need 2400 pixels by 3000 pixels of information. If you wer
displaying an image on the internet (where 72 pixels per inch i
acceptable) you would only need 576 pixels by 720 pixels.

So how many megapixels do I need?
Each camera displays data in slightly different ratios but there ar
some "rules of thumb" you can follow. Decide what the largest size imag
you will want to print. For most people this will be an 8x10 image
Determine the number of pixels needed for a 300dpi print (2400x3000 fo
an 8x10). Next multiply the two pixel dimensions together. For an 8x1
this comes out to 7.2 million pixels, or 7.2 megapixels. This is th
preferred number of MP you need if an 8x10 print is the largest you ar
likely to print

Abigail1, Oct 17, 2012

2. jdanieldGuest

Le 17/10/2012 08:27, Abigail1 a écrit :
it's not for an inch, anyway the sensor is a surface it could be
square inch, but it's neither.

its the number of pixels for the hole sensor surface, with no respect
of it's size.

A 8Mpix sensor can be Full frame, APS-C, mini...

jdd

jdanield, Oct 17, 2012