Canon Speedlite 580EX II Flash for Canon EOS Digital SLR Cameras

It communicate very well with my Canon 20D. The 589EX II will act the same as the built-in flash of 20D, except it is 16 times more powerful. The power level adjustment is useful for multiple flash set up. I have been considering to buy it for 2 years. My hesitation is due to the steep $500 price tag and my Vivitar 285HV. After using it for 2 weeks. I can kick myself not to buy it earlier. The ETT II gives me excellent exposure ( no more wash out of the object) regardless of the back ground, that the 285HV cannot do. It is a perfect flash for my 20D.
I have five friendly advices:
1. Set C.Fn 6 to 1. This enables the quick flash mode. The flash can be fired without a full charge. Good for rapid shooting at a reduced range.
2. Use rechargeable batteries. This will make the flash charges faster. Also you are helping to save the earth.
3. This is the most powerful flash that Canon makes. From my 40 years as photographer, you should buy the most powerful flash. Do not buy the lower model even you can save $150. The 580EX II will allow you to use a smaller aperture to do a better job as a fill in light for the shadow under the sun or have a faster recycle time when shooting at night. Also you will still have enough light output even with flash attachments, i.e. diffuser, reflector etc.
4. The 580EX II tends to be slightly (1/3 to 1/2 stop) under-expose the object. It may not be a problem if you prefer slightly saturated color. Otherwise you can give it a +1/3 or 1/2 flash exposure compensation( It is much easier to set it up on the camera rather than on the flash) However,it will be perfect as a fill in flash for shadow underneath the sun without using flash exposure compensation.
5. In order for the TTL II to work right, make sure that the lens you use will pass the distance information to the camera and hence to the 580EX II.

Complain: The owner's manual does not spell out some of the interaction between the camera and the 580EX II. e.g. the high speed syn will be disabled automatically if the shutter speed is below the maximum normal flash syn speed, high speed syn will not over heat the flash as long as it obeys the rule for maximum number of consecutive normal flash, The focal length indication shows the real focal length of the lens, not the equivalent focal length of the APS-C sensor, any focal length shorter than 24mm still indicates as 24mm, even the Zooming flash head might have zoom to 27mm equivalent(17mm actual) focal length.Get more detail about Canon Speedlite 580EX II Flash for Canon EOS Digital SLR Cameras.