Megapixels, Megabytes, and Resolution … Oh My!

Antarctic Coastline, by Wayne Divoky

Ken Duquaine

Megapixels, megabytes, and resolution can be confusing terms for someone new to photography, but even many experienced photographers have difficulty sorting out the differences. All three are measurements that are important in determining how a final image will look, but they are not interchangeable terms.

Megapixels (MP) measure how many pixels a given camera will capture in an image, and a camera’s megapixel count is fixed. One megapixel equals one million pixels, and so a 10-megapixel camera will capture 10 million pixels. That same 10-megapixel camera will produce an image that is roughly 2,592 pixels by 3,888 pixels. Multiplying the dimensions of the image together (2,592 x 3,888) equals about 10 million pixels. Generally, the higher the camera’s megapixel count the sharper the resulting image will be, and the larger the prints made from that image can be, but only up to a point. The size of a camera’s sensor, e.g., full frame versus crop sensor, will determine the size of the pixels and the resulting quality of the print.

Megabytes (MB) measure the size of a digital file. One megabyte is equal to one million bytes. Often this measurement is used to determine how much space a file will take up on a memory card or a hard drive. File sizes vary and will change depending on a number of factors that include the resolution of the image, the format that the image is saved in, and the degree of compression of the file.

While resolution and megapixel count are closely related, they are not interchangeable. Resolution tells us the level of detail that a camera or an image can provide. Resolution depends on several factors, including the density of pixels on a sensor, sensor size, ISO, lens sharpness, and diffraction. One of the primary reasons for shooting high-detail images is the option to crop in post-processing. Once the work on a high-resolution image is completed and it’s ready to be sent off, one may consider saving the image in a different resolution, depending on its intended use. If one is planning to print photos, a high megapixel camera is desirable. To achieve a detailed, clear print of a photo, the recommended resolution or pixels per inch (PPI) is 300. The formula for determining the number of megapixels required to print photos of a given size is print width x 300 x print length x 300. And, so, a 4×6-inch print requires 2.2 MP, while a 16×20-inch print would require 28.8 MP.

The Sun Lakes Camera Club (SLCC) meets the first and third Thursdays from 6:30 to 8:30 p.m. in the Mirror Room of the Sun Lakes Country Club from October through April. For more information about the SLCC and its activities, contact SLCC President Samantha (Sam) Palmatier at 902-727-0334 or [email protected], or past president Lynn Thompson at 480-734-0040 or [email protected], and visit our website at