Hello Forum Members,
I have recently started to use my flash off camera and in order to do that I use Yongnuo radio for Canon on Canon 5D MKII. I noticed that the camera does not "recognize" the transmitter that is inside its hot shoe as a flash and therefore does not show the flash icon in the camera's view finder. As a result several things happen:
1. The camera thinks that there is no flash and therefore meters the lights incorrectly.
2. Using the AV and TV modes is impossible as again the camera thinks that there is no flash and adjusts the shutter speed/aperture (depends on the mode) to wrong values which in turn cause over exposed photo when using flash. The only solution is using Manual mode.
3. The flash TTL mode is irrelevant as the flash does not receives any info through the radio and therefore fires at maximum.
If anyone came across this problem, please kindly assist with a solution.
1) The camera always meters for ambient light. If I use my Mk II with one of my Canon flashes -- such as the 580EX II -- it still meters for ambient. That's because there are situations where I might want to "drag the shutter" for a better background exposure. What it will do is if you're shooting in Program mode (so the camera can start with any baseline exposure settings it wants) it will not pick a shutter speed higher than the flash sync speed when it knows there's a flash on the camera.
2) That sounds like a problem of TTL compatibility. Is this flash supposed to be TTL compatible (E-TTL and/or E-TTL II)? What the camera should do is fire with the the flash twice (so quickly that you probably wouldn't notice it's firing twice.) The first time it fires the shutter is CLOSED. It fires at a fraction of full power (I think the default on my flash is 1/32nd power but I can change it.) It meters the scene with no flash, with flash at 1/32nd power, and it compares to determine if there are ambient light sources in the scene (which are then ignored) as well as reflections in the scene (which are also ignored.) It looks for areas where the flash actually made a difference between the flash and no flash. It then calculates how much power should be used for the "real" exposure. It then opens the shutter and fires the flash a 2nd time. This all happens _very_ fast.
3) Radio? There is no radio in a 5D II. Are you using a 3rd party radio such as a Pocket Wizard FlexTT5 and or FlexTT5 with a MiniTT1? That's the only way you'd get TTL support via a radio triggered remote flash. If you use a remote flash, its manual settings ONLY. You have to know the flash output of your unit and learn to manually pick the f-stops based on the distance and power level of your flash. You could also buy an external light meter that knows how to meter for "flash" (rather than just ambient.) A Sekonic 308 is probably the most basic meter that I know of that can do this. But a 358 can deal with ambient/flash contribution calculations (a very nice feature to have.)
The 3rd party flashes are attractive because they're inexpensive. HOWEVER... the brand name flash units (e.g. Canon and Nikon speedlites) offer a lot of features besides just making a bright pulse of light for a fraction of a moment. The units may work as slaves-only or master-or-slave and might have built-in communication. The TTL features may work even when remote. They also usually support things like high-speed sync, multi-strobic modes, 2nd curtain modes, and the list goes on. I find that when I CAREFULLY scrutinize the feature of a 3rd party flash (e.g. the Yongnuos) they don't actually have all the features that the Canon or Nikon units would have. When I do find units that actually support all the features, I find the price difference isn't very much... e.g. I might find I can save $25-50 by purchasing a 3rd party flash vs. a $400 Nikon or Canon flash... but then I know that Nikon and Canon don't actually work with these 3rd party makers to help ensure compatibility. These things are reverse engineered. So I ask myself... is it worth it to save $25-50 on a flash which is "supposed" to be as good, KNOWING that they had to reverse engineer the compatibility (which is complex)? I've read too many horror stories ... even of people using Pocket Wizards that provide the TTL compatibility only to discover that it's not actually very reliable.
HOWEVER... if all you want is a flash that works on "manual" mode (which a LOT of photographers use... manual isn't actually that hard once you learn the principals involved and know the inverse-square law (which is also not that hard)) then those 3rd party units are fine. It's when you want to do TTL modes or wireless with TTL that you get into trouble.
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