Resolve to Understand Resolution

When I got my first digital camera, I spent a couple of months trying to understand all the fuss about resolution. I read articles and books, and talked to everyone I could about why it mattered. Mostly I ended up more confused – there were so many different definitions of resolution, and no ‘5000 foot view’ of it that made sense to me. Then one day, someone casually gave a simple explanation that made it all snap into place for me. I hope it helps you too!

 

An image’s resolution (measured by its pixel dimensions for my purposes) determines how it will look on a monitor, how well it will print out, and its file size.

 

All digital cameras can take images at different resolutions. The lowest resolution is usually 640 pixels wide by 480 pixels high, the highest resolution varies by camera. For example, if your camera is a 5 megapixel camera, the dimensions of an image taken at the highest resolution would be 2560 pixels wide by 1920 pixels high.

 

Let’s look at the results of taking a 5 megapixel image.

 

Most monitors are set to display 1024 X 768 pixels (if not less). Displaying a 5 megapixel image at full size (2560 X 1920 pixels, or twice the size the monitor can show) will result in your seeing less than half of the image  - you will have to scroll up and down and side to side to see the whole thing.

 

You need between 200 – 300 pixels per inch (ppi) to get a good print which means that you can get a good 8 X 10 (2560 pixels/10” = 256ppi and 1920 pixels/8”= 240ppi), and a great 5 X 7 (2560 pixels/7” = 365ppi and 1920 pixels/5” = 384ppi),  print out of a 5 megapixel image. Note however, that you will NOT have that many pixels if you crop the image!

 

A 5 megapixel image will result in a file size of 2.5 – 3.5 megabites. Why should you care? Well, file size will dictate how many images you can fit on your card for one thing. Sending files of such a large size by email can be a problem if you or the other person are still on dial up, or your or your recipients email provider limits the size of file attachments.

 

The bottom line is, you need HIGH resolution for good prints, but LOW resolution (also file size) for viewing and sharing images electronically (on the web or email).  So, how does one resolve this conflict?

 

~ Take the picture at the HIGHEST resolution (and the LOWEST compression) that you have room for on your card.

~ Move close and/or zoom to fill the screen with your subject (to avoid cropping later), then pull back a bit to allow some ‘wiggle room’ for rotation (this is where a high zoom lens comes in handy!).