TTL and 420ex flash

Hi everyone, I am giving serious consideration to purchasing the 420ex flash for my G2 however I don't know what TTL or E-TTL is or does, and I don't know if there are any compatibility issues.
Can anyone shed some light on this for me?
Any and all info is greatly appreciated !

P.S. If anyone knows of any websites too, that would be great

Hi!

Take a look at http://www.botzilla.co​m/photo/G1strobe.html - lots of information.

Regards Sherman

I have a G2 and a 420ex.

1. The on board flash on the G2 works well (has a tendancy to overexpose a bit) but only has a range of about 10-15ft. Suitable for "round the table pictures" but not good enough for longer distance shots.

2. The 420ex works with the autoexposure/focus system of the G2. It increases your flash range to a possible 100ft or so based on lens settings and exposure. It works automatically.(E-TTL is what does this)

3. The 420ex allows bounce flashing (reflecting the flash off of ceilings/walls) for a softer lighting and less shadowing.

4. The 420EX will reduce red eye as the flash is higher on the camera and with the increased angle the flash will reflect off the retina at a greater angle and reduces red eye effect.

5. The 420EX does make the camera heavy and awkward. I got around this by adding a lensmate adapter and a uv filter which gives you a place to use your left hand to steady the camera. (the lensmate also protects that great canon lens)

6. If you shop around you can get a decent price on a 420ex but it will be more expensive then non-canon flashes. Some non-canon flashes will only flash at one level so you have to manually set your aperature or timing with each shot.. the 420ex is automatic and knows what level to flash just like the onboard flash. Also the camera knows the 420ex is on it and autmatically reconfigures itself accordingly.

7. The 420ex is a great flash... if you buy it, find you do not like it then it will be very easy to resell and probably get most of what you paid for it.

8. When I was at a function, one of the professional photographers was using a high end canon camera body with a huge high end canon lens (it was about a foot long lens).. he was using a 420ex as his flash.