canon did it again: 580ex II

Started Oct 29, 2007 | Discussions thread
Phil Tower Regular Member • Posts: 223
Re: canon did it again: 580ex II

Wick Smith wrote:

I don't quite see the problem. With the most recent cameras the ISO
and aperture are communicated to the flash when in external sensor
mode. With earlier cameras, you need to set the aperture and ISO
manually, as you did with older flash units like the Vivitar 283.

Why do you see this as a plot to get you to buy a newer camera?

The 580EX II (unlike the 580 EX and other EX predecessors) has an external automatic flash exposure sensor, which provides the option of automatic flash – but not TTL. This is "automatic" flash using the flash's own sensor (as opposed to E-TTL which uses the camera's sensor). As many have pointed out, this "new" feature on the 580 II is akin to the older thyristor flash units.

With any EOS camera, you can use this external "automatic" feature on the 580 MK II by using the "manual" external flash exposure mode (not to be confused with the camera's manual mode for manually setting speed and aperture). Using this external "automatic flash exposure" "manual mode", you can manually set the ISO and aperture on the flash itself to match the camera's ISO and aperture settings.

If you want flash exposure to intentionally be greater or less, you can set a different camera lens aperture than the one you’ve set on the back of the flash, or change the camera’s ISO to a different value than the one you set on the flash.

To be clear, this function on the MK II is available using any EOS camera - film or digital.

The 1D MIII (and I believe the 40D) has an "automatic mode" for the external "automatic flash". This automatic external flash mode is turned on in the camera's Custom Function 05-2 – External metering: Auto menu setting. Here, you do not have to manually set the camera's ISO and aperture on the flash itself. The camera feeds that information to the 580 II automatically. However it should be mentioned that in this mode, you do not have the ability to force the flash exposure to intentionally be greater or less as you can in the external automatic flash exposure, manual mode.

So, the OP is correct in stating that the 580 MK II external automatic exposure, automatic mode will not work with the older EOS cameras. And as he points out (I have not tried it myself on my 400D - in fact, I haven't even taken the 580 II out of the box yet and put it on my 1DIII), you can set the 580 MK II's external flash mode to auto mode on the flash itself and the flash is "seeing" the camera's ISO and aperture settings. But, according to him, the flash won't trigger in that setting on anything but the 1DIII (and possibly the 40D).

Thus, it would appear that Canon may have intentionally disabled this feature. How big a deal it is, and whether it deserves all the discussion and hostility it is generating in this thread I will leave to others.
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Phil Tower

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