Good results with 10D and 580EX

That's right. I was expecting better results....
But, I have already learned there is no magic in the world.

Well, just another question about zoom of 580EX.
Manual says that the flash "automatically recognizes the EOS digital camera's image size and automatically sets flash coverage foe lens focal length from 24 mm to 105 mm."
The question is:
When I zoom my lens to 70 mm ( the 35 mm equiv focal length should be about 110 mm at this point)
My flash is showing 70 on the screen. Actually, I was expecting it will show me the real zoom for the flash.

I wanna make sure the flash recognizes the camera.

It only recognizes the sensor size on cameras that pass that info along - the 10D didn't, because they didn't have any flashes that wanted that info. The 20D (and 1Dx Mk IIS?) and now, presumably, the new DR, will be able to do this.

Well, how can I check that...?
I have 20D and 580EX. It should recognizes...

I don't think the flash zoom setting's recorded anywhere in the EXIF data. You might be able to get an idea by putting a wide angle lens ( wider than 24 mm) and see what it does. The only other way, short of some fairly sophisticated test set-up, that I could think of would be to use two cameras in a dark room. With the flash on one, and a wider lens on the other, line the two up on the same wall area (the second camera would need to take in more area than the first, say use a 28 or wider while using a 50 on the camera with flash) from the same distance (as close together as possible), take a time or bulb exposure with the second and fire the first with flash. If the flash is adjusting properly, you'll see the entire flash area in the exposure from the second camera.

No offense, but I think it's pretty obvious that the top-of-the-line flash is recommended .....

Jon + Kost

You raise interesting points; however, I was specifically told by a Canon rep that the 580EX does recognize the 10D sensor size, and that this was reason for 10D owners with a 550EX to upgrade (albeit a pretty minor reason).

However, I should note that on my 20D, my 580EX reflects only the focal length of lens and does not add the 1.6 sensor crop factor on the readout on the back of the flash.

Regardless, the 20D and 580 combo give me some of the most remarkable indoor flash exposures I've had - and I've used a D30/60/10D with a 420EX and 550EX.

Just curious then, has anybody else say using a 50mm lens on a 20D with a 580, seen the 580 actually read the focal length as 80 (i.e. displaying the sensor crop factor), instead of 50 (as has been my experience.....my guess is that its factored in but not displayed)?

chuck

I don't think that I said that the reading displayed would be that of the crop-equivalent focal length; you will notice that the 580 shows an icon for sub-35 mm formats on the display, however.

I played a little bit with the flash and camera...

I just found that when I set the lens to 70 mm the flash goes to the last zoom position (but still showing 70 mm on LCD).
That's the way this system works.