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Occasional Contributor
Posts: 13
Registered: ‎06-16-2013
Accepted Solution

7D & 580EX

When I use my 580EX flash with my 18-135 STM, the flash only shows 28-105.  Is this normal?

Canon 7D
Canon18-135 STM, 70-200 F2.8
2X Extender
Canon Elph 330HS
Canon Elph SD750
Esteemed Contributor
Posts: 3,854
Registered: ‎06-11-2013

Re: 7D & 580EX


There's a reflector inside the head of the flash which slides closer or farther from the flash tube to control whether the flash creates a narrow or wide spread of light. The flash can automatically move the reflector (you can also put it in manual mode) to match the lens -- but the those are the limits of travel.

There's a wide-diffuser panel stowed in the top of the flash (along with the bounce card). You can pull the panel out and swing it down in front of the light to create a wider spread.
Tim Campbell
5D III, 5D IV, 60Da
Reputable Contributor
Posts: 790
Registered: ‎06-11-2013

Re: 7D & 580EX

[ Edited ]

In this case, because you are using the 18-135 on a crop sensor camera, at the wider setting the flash is factoring in the crop and correctly using the 28mm setting. The flash is actually capable of setting slightly wider automatically, but the flash's 28mm setting is the correct setting for this lens zoomed to 18mm on that camera.


But, yes, there is the diffusion panel on the flash, too. That can be manually engaged and is designed to accomodate up to 16 or 17mm wide lens, if memory serves, on a full frame camera. That would be equivalent to a 10 or 11mm lens on your 7D.


At the tele setting, 105mm is simply the longest that the flash goes. You would still see that even if using 200mm, 300mm or even longer lenses on the camera. There are flash extenders available, if you ever need to accomodate a longer lens like these, but I wouldn't bother with 135mm on a 7D.


Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories


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