MR-14 and 40D

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Archive 2008 · MR-14 and 40D

runnermikedmd
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p.1 #1 · MR-14 and 40D

I recently purchased a MR-14 EX ring light used. When I put it on my 40D, it looks like the ETTL isnt working right. About 50% of my images are way over exposed. I havent used a flash at all before, so it may be something simple I am doing wrong. Just wanted to check before I return it if I am missing something simple. When I open up the flash control menu on my 40D, the spot where you select ETTL is greyed out. If it makes any difference, I have a Tamon 17-50 f2.8 mounted.

Any ideas? Or should I cut my losses and return it?

Thanks!

Dec 17, 2008 at 02:30 AM

cgardner
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p.1 #2 · MR-14 and 40D

Haven't used an MR-14 but on any other Canon flash you don't need to set anything on the camera. Just put the flash power pack in the hot shoe and set the flash control to ETTL. Flash is simpler if you use the camera in M mode.

In the camera CF.n menus you will see the option to set ETTL-II flash metering to either 0 - Evaluative or 1 - Average. Leave it at the 0 default.

The ETTL-II metering reacts to the reflected pre-flash. It evaluates pre-flash against ambient over the 35 metering zones and can identify lightest and darkest zones, range of scene, relative distances (pre-flash return is like radar). Then it makes an educated guess what % of total capacity the flash should fire at. The guess more accurate when what you want correctly exposed is composed closest to the flash.

When camera guesses wrong, as it does about half the time initially, you override it with FEC. FEC can be set on camera, or via the flash, which overrides the camera setting. But if FEC is turned back to 0 then the camera setting will kick in again. To avoid confusion use one or the other. I find adjusting on the flash simpler since the setting is displayed.

The simplest way to evaluate exposure is via the over-exposure (clipping) warning. Adjust FEC so any white highlights with texture are 1/3 below clipping. Have the bug hold a tiny white towel

There's also the possibility you set the controls on the flash incorrectly. The two sides of the ring can be controlled separately as A:B groups and the MR-14 can also function as master for other Canon flashes. Read the manual and work through the examples.

Chuck

Dec 17, 2008 at 03:04 AM


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