Most of my photographs are in the 2:3 image aspect ratio which looks great when people want 4 X 6 prints but looks awful if people want 5 X 7 or 8 X 10 prints.

I know that with the 2:3 aspect ratio that these print sizes are also not cropped: 8 X 12, 10 X 15, 12 X 18, 16 X 24, 20 X 30 and 24 X 36. It seems that people can only get acceptable, uncropped prints from either the relatively small 4 X 6 size or these large sizes which most don't want because they are too big and expensive and don't fit in standard frames.

Is it best to not make available choices that result in my images being cropped? What do you with professional accounts do?

It's the ultimate irony that pro cameras, from which people order 5x7 and 8x10s, are 2:3, whereas consumer cameras, from which people order 4x6s, are 3:4. Pheh.

Our shopping cart with the crop lines is 99% effective when people order enlargements in getting them to notice and choose their own crops. However, it's not 100% effective (some people just don't notice the crop lines and don't know for cropping), and if you don't leave enough room on the ends they end up making tough decisions, like whether to lose the groom's head or feet.

So I crop mine to 3:4 before uploading because it's close enough to most print sizes.

This is an excellent example of one advantage the four-thirds system (olympus E-1, E-300) has over other SLR cameras. As the name implies, the sensors in these cameras have a native 4/3 aspect ratio sensor.

-Winn