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80D and 580EX II


I have had these items for a number of months and am trying to learn more.  I have some basic questions.


First, I understand that in order to use the 580EX II as a Slave with the 80D, the built-in flash is used as the Master.  That's fine.  Suppose I want to use the 580EX II as a Slave and attach a Rode Stereo Microphone on the 80D hot shoe.  How does this impact the built-in flash's ability to act as the Master flash?


Secondly, maybe I have really weak fingers.  The flash unit takes some effort to slide into the hot shoe as it is.  When I have it all the way forward, then there is the issue of the locking lever.  I move the lever to the right as far as I can possibly push it, but there is no "click" sound when it gets to the point where I cannot push it to the right any further.  It seems like the flash unit is tightly attached to the camera hot shoe, but I never heard any "click" sound or sensation.


I took one picture with the camera set on "Auto".  The flash unit lcd display said "ETTL", so I assume that is okay.  I will have to do a lot more experimentation before I can say any more.


Finally, I hope this ended up being a "new" post, as I am somewhat confused by the new topic posting instructions.  I apologize if it ends up being something else.



You wont be able to raise the built-in flash if you have anything attached to the hot-shoe.  This is because raising the flash would collide with whatever is attached.  Canon has a tiny micro-switch (button) hiding under one of the leaf springs on the hot-shoe rail which is how the camera knows if you have slide something into the shoe.


The mic is typically used for "video" but flash is not typically used in video... that's used for still photos.  But if you want it all connected so you don't have to disconnect the mic to use the flash, then lower the flash to re-attach the mic for video... then I'd get an inexpensive "flash bracket".  These brackets were far more common in the days of film when having a flash too close to the lens could result in "red eye".  Today we digitally remove the red-eye so there's no longer an emphasis on getting the flash high or to the side.  But you can still buy flash brackets and connect the rode microphone to the bracket and that would free your hot-shoe so you can raise the built-in flash.


The camera and flash will normally use "E-TTL II" mode.  "TTL" stands for "Through The Lens" metering.  It's a mode where the flash sets its power level automatically by working with the camera's metering system.  


The short version is ... this system allows the camera & flash to automatically work out the correct amount of power for your shot.  Basically if it's in E-TTL II mode, then you mostly don't need to worry abou controlling the power on the flash ... it's automatic.



If you want to how it does this... here's a short explanation.


In this system, the camera & flash work together each time you take a shot and they do four things VERY fast.


#1 - the camera meters the scene using evaluative metering ... checking the light level in each "zone" of the evalautive metering system.


#2 - the camera fires the flash at a reduced power level (typically 1/32nd power) WHILE simultaneously metering the scene again.  At this point the camera shutter is still closed.


#3 - the camera compares the metering of each zone between the metering measurement from #1 (no flash) vs. #2 (with flash).  It determines how much of an improvement the flash made (at 1/32nd power) and uses this to calculate how much ACTUAL power should be used when the camera takes the shot.  It might also factor in the lens focusing distance (only if the flash is mounted in the hot-shoe and pointed directly ahead... if you tilt the flash head up or sideways then this feature is ignored.)


#4 - the camera opens the shutter and takes the shot with the flash firing at the power level calculated in step #3.


This all happens so quickly... you'd swear the flash only fired once.


One of the benefits of E-TTL II is that it was designed to be more difficult to fool than previous generations of TTL flash.  In older metering systems, objects in a scene with varying levels of reflectivity could confuse the system (bride in "white" highly reflective wedding dress vs. groom in "black" non-reflective tuxedo).  The current generation of the technology is pretty clever and while I would not say it's imposible to trick it... it certainly is more difficult to trick it.  Most of the time it does the right thing.


I'm not sure what to say about the locking foot on your 580... it almost sounds like the foot is too tight.  It's normally not particularly difficult to slide in or out of the hot-shoe.  There's a small locking pin that should drop down into a tiny hole in the plate -- this happens when you slide the lever to the locking position and it's meant to prevent the flash from sliding in the hot shoe.  It's not just "clamped" snugly.. it's actually got a locking pin.


Syl Arena's book "Speedliter's Handbook" is an excellent book on the Canon flash system.  It's currently in it's 2nd edition but Syl mentioned there is a 3rd edition already written and expected to release sometime this year.


I should warn you that prices on Amazon for a copy of the 2nd edition are ridiculously expensive (you'll think you're buying college textbooks that cost hundreds of dollars).  The most affordable way to get a copy of the 2nd edition is on the Apple "iBooks" (electronic) platform ... but that would require that you own a Mac, an iOS device.  For some reason it is not available on Kindle.  


I'm guessing the 2nd edition is priced ridiculously because they've run out of copies for the 2nd edition and if you want one, those who have it want a lot of money.  When the 3rd edition is released, prices should immediately return to a sanity.


Tim Campbell
5D III, 5D IV, 60Da

Thank you. Perhaps I will take my camera and flash to a local camera store and see what they have to say about the "fit" of the flash unit. I bought it from

I have some more time, so I thought I would respond with a more thorough commentary.  Since the first reply, I  logged onto Canon and have prepared the necessary documentation to send the flash unit out for repair.  Since it is only a few months old, I assume it will be covered under warranty.  I have a 430EX II, and I decided to attach it to the camera, and you are right, it slid on very easily and the "locking ring" went all the way to the right and "clicked."  I went back to the 580EX II.  I decided to try pushing the locking ring to the right off the camera, and it just would not cooperate.  So, off it goes for repair / replacement.  I looked up "The Speedliters Handbook", and you are correct, it is quite expensive.  However, I took a beginner's photography course at a local community college, and the text used in that course was "Real World Digital Photography" by Katrin Eismann, Sean Duggan and Tim Grey.  I cannot recall how much I paid for it, but it retails for anywhere between $60 to $100+ now.  I also own "Adobe Photoshop, Classroom in a Book", 2013 edition,  another expensive tome. I notice they have come out with a 2018 edition, which retails for over $64.


I have watched some online videos on how to use the 580EX II, so I understand how the built-in camera flash is the "Master" and the 580EX II can be used as a slave.  I guess I was thinking about video.  The stereo mic can be plugged into the camera and placed on a boom stick if need be.  Something I can hopefully design myself . . .


Thank you again for yourthoughtful and thorough response to my concerns.

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