michael_ziegler2 Posted November 2, 2009 Share Posted November 2, 2009 <p>Normally the bars on the back of the flash (which indicate the effective distance range) start from the far left and end at the right side of the display. There are some combinations of ISO lens mm setting and aperture where the bars start in the middle of the display and end at the right.<br>How is this display to be interpreted?</p> Link to comment Share on other sites More sharing options...
jim_simon3 Posted November 2, 2009 Share Posted November 2, 2009 <p>I've always assumed that it meant it would blow out the picture at a lesser distance. That is, the flash can't reduce it's power enough to take the shot at close range with the settings you chose. It is the same on the 550EX as the 580EXII.</p> Link to comment Share on other sites More sharing options...
steve_dunn2 Posted November 2, 2009 Share Posted November 2, 2009 <p>That response is correct. Flash units can't reduce their output below a certain level, so for some combinations of zoom position, subject distance, ISO, and aperture, the flash cannot help but overexpose the subject.</p> Link to comment Share on other sites More sharing options...
michael_ziegler2 Posted November 2, 2009 Author Share Posted November 2, 2009 <p>Thanks guys for the input. I did believe what you both said was correct. However, I had not seen any literature from Canon supporting that conclusion and felt I needed some corroboration.</p> Link to comment Share on other sites More sharing options...
steve_dunn2 Posted November 3, 2009 Share Posted November 3, 2009 <p>My flash is a 420EX, which lacks a distance indicator, so it doesn't show that. But the manual does specify its range, with a given lens (50/1.4) and ISO (100), and the minimum range is given as 0.7m. I suspect there will be a similar statement in your unit's manual, though it probably won't state <em>why</em> there's a minimum.</p> Link to comment Share on other sites More sharing options...
michael_ziegler2 Posted November 3, 2009 Author Share Posted November 3, 2009 <p>I am now thinking that the minimum is caused by the angle of the light path of the flash v.s. the angle of coverage by the lens being used.</p> Link to comment Share on other sites More sharing options...
model mayhem gallery Posted November 5, 2009 Share Posted November 5, 2009 <p>Like the said it is stating the min and max. You can reduce the minimum by going manual and turning flash power down or using something like a stofen ominibounce.</p> Link to comment Share on other sites More sharing options...
michael_ziegler2 Posted November 6, 2009 Author Share Posted November 6, 2009 <p>Minute, I trhink the ETTL varies the power automatically.</p> Link to comment Share on other sites More sharing options...
model mayhem gallery Posted November 7, 2009 Share Posted November 7, 2009 <p>oops. Truthfully, I've had my 580EX for over a year but I've never paid any attention to the distance indicator so I can only guess at what this middle of the display issue means :-( </p> Link to comment Share on other sites More sharing options...
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