The infrared based ST-E2 transmitter mounts in the hot-shoe of your Canon camera and can trigger any number of off-camera speed-lights in two different A-B groups that are equipped with the proper infrared receivers ... (compatible speed-lights such as Canon 420EX, 430EX-II, 550EX, 580EX-IIs to mention a few).

The ratios quoted indicate the ability to control the output of each speed-light (or group of speed-lights) from the camera ... so for example a 1:1 ratio set on two speed-lights would produce equal light from both flashes (which is the default setting if I recall correctly) ... an 1:1 set on one A group flash and 1:2 on the B group would produce full output from one, and 50% output from the other. "With-in 1:8 to 1:1 or 1:1 to 8:1" simply means you can select any ratio with-in that range while selecting which flash is the primary "key" light.

A simple example of that is a "key light and fill light" scenario. You can light a subject using one light at 1:1 ratio full output (A group key light), and set the other at a lesser ratio like 1:2 output which will be 50% output and act as a B group fill light. Note that the primary, key light need not be 1:1 ... it can be anything you want from 1:1 to 1:8 ... but the secondary flash used for fill should be a lesser ratio.

Having a "group" means you could have a 1:1 key light in A group, and two speed-lights in B group set to 1:2 ... A= Key light, B= Fill light and accent or hair light.

Be aware that any infrared type flash trigger is a line-of-sight type system ... the receiving flashes must be able to "see" the transmitter in the camera hot-shoe and the distance from camera to off-camera flashes cannot be to great. For best results make sure the line-of-sight is not blocked, and turn the body of the receiving flash so the infrared receiver is pointed toward the camera, rather than facing away from it.

Radio based systems do not suffer from these limitations ... Notably, Canon is the first manufacturer to offer a built-in radio based speed-light system with the 600EX-RT speed-lights which are compatible with their newer cameras.

Marc Williams
FOTOGRAFZ, LLC

I had the Nik Silver Effects Pro program, and when Google bought them was offered the remaining software in the bundle for a very nominal fee (actually, I think it may have been a free upgrade).

I also have OnOne's PhotoTools software.

Nik cannot be beat for B&W in Nik Silver Effects Pro-II, however, I find the OnOne Photo tools more useful and easier to use than the Nik Color Efex.

The Nik color program has more "spectacular" color effex, but the OnOne has more practical tools ... for example, their skin retouching set is extremely good IMO.

To keep my reply in perspective, I am primarily a wedding and portrait photographer.

- Marc