topic Re: 7D & 580EX in Speedlite Flashes

7D & 580EX

jimsaloha — Sun, 14 Jul 2013 21:50:43 GMT

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

Re: 7D & 580EX

TCampbell — Mon, 15 Jul 2013 13:32:34 GMT

Yes

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.

Re: 7D & 580EX

amfoto1 — Mon, 15 Jul 2013 17:31:08 GMT

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.

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Alan Myers

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