4x6? 8x10? 4:3? 16:9? Possibly the last thing on your mind when you're taking a picture. Especially so if you didn't know that these setting can often be changed *before* you even line up the shot.
Let's back up a bit.
What are those numbers? 4x6 is a measurement, in inches, of the smallest (non-wallet sized) printed photograph. It's also a ratio which can be expressed in a few different ways. 4x6 = 2:3 = 8x12 = 12x18. The last two are larger common print sizes. 2:3 is the shorthand for that camera setting - but more on that later.
4:3 you might have heard of. It's the ratio for the 'Full Screen' TVs. It's also the default ratio for a lot of Point and Shoot Cameras. Unfortunately, not much else. You can print an 8x6 - but it's rather difficult to find a frame for it.
Why am I going on about this?
In simplest terms some ratios/sizes can best be described as tall (or wide depending on orientation) - such as 4x6, 5:3 (Widescreen Photoframe) and much more so 16:9 (Widescreen TV).
Others such as 4:3, 8x10 and 8x6 can more aptly described as square-ish.
... And your point is?
As mentioned in the beginning of this post - you can likely set your camera's aspect ratio. Depending on what you're going to do - show them on a 'full screen' TV, widescreen, print 4x6s or 8x10s - it might be worth it to plan ahead. Either by changing the camera's settings and/or composing your shot with the above in mind.
If I don't?
Quite simply, you're going to lose some of your picture.
You'll have to crop it down - making for more work and possibly some tough decisions - OR leave that process up to the software on the Kiosk. There's a good chance you won't notice, if the edges of your picture are 'background' you'll probably have to see a side by side comparison of the print and the preview to even see what's missing. If you're someone who likes to go edge to edge- watch out!
There is a somewhat helpful second option, which I'll refer to as 'Anti-Widescreen'. Since the 'highest' setting of the average point and shoot camera is often tied to the less than ideal 4:3 ratio this name fits. What you can do on most Photolab Kiosks is to 'Zoom Out' a picture - which will *add* white bars to the left and right edges of an otherwise squarish picture to fill out the rest of the 4x6. If you don't like the television 'Widescreen effect' - this probably won't sit well with you either. The purpose, however, is the same - you don't lose any of your picture - you just 'gain' nothingness.
A point and shoot camera set at 4:3 - image cropped (somewhat poorly) down to the ratio needed for a 4x6 print
Camera set to 3:2 ratio - cropped in preparation for enlarging to 8x10
The software pictured above is Picasa3(.6). A rather handy program for organizing pictures, pre-cropping them and a number of other useful tasks. With the latest version you can even set your own custom cropping ratios. It's also free and a rather small download. Various plugins can be used to help you upload to sites like Facebook.