Yongnuo YN568EX II underexposing when bouncing.

I got the flash today for use on my 1D III. When in E TTL mode, it properly exposes pics when the flash is aimed forward. But if I bounce it off the ceiling it's underexposed. Is it underexposing because the flash to subject distance is being taken into consideration? Is there a mode to cancel that? Am I doing something wrong?

It shouldn't, but even with name brand stuff you'll run into issues like this. Just use flash compensation, that's the reason Canon puts it into the cameras.

Also try both evaluative and averaging mode to see if it makes a difference.

I almost always have to use +1/3 to +2/3 depending how far away from the subject I am when bouncing

OK thanks. But after some more test shots I found the strange thing is when bouncing the more you zoom in the more you need to compensate to the + side with the 24-105L. For example, at 24mm +.7 is necessary but at 105mm you need about +1.7.

f1.4bthere wrote in post #17756554
OK thanks. But after some more test shots I found the strange thing is when bouncing the more you zoom in the more you need to compensate to the + side with the 24-105L. For example, at 24mm +.7 is necessary but at 105mm you need about +1.7.

Is your flash auto zooming?

I tried the different types of metering modes and no difference.

gqllc007 wrote in post #17756555
Is your flash auto zooming?

Yes.

The best way to get consistent exposures is to use the flash in manual, especially if you're bouncing the flash.

ShotByTom wrote in post #17756561
The best way to get consistent exposures is to use the flash in manual, especially if you're bouncing the flash.

Seems like you shouldn't have to do this-I mean it's TTL. This reminds me of when I went digital with Nikon. I gave up on Nikon's digital TTL flash(same result with 2 different bodies), sold the SB-800, and just use the older flashes in A mode where the sensor on the front of the flash determines correct exposure. Guess I got spoiled on Nikon's film TTL flash which was great.

These are both +2/3 bounce TTL with virtually no changes in lightroom applied

f1.4bthere wrote in post #17756560
Yes.

That's a worry, with the head tilt edit shouldn't be. When you tilt the head it should zoom to 50 and stay there.

I realized it only zooms to 70mm in auto zoom mode. Manually it will zoom to 105mm. There may be something wrong with it, so I want to send it back to B&H and exchange.

f1.4bthere wrote in post #17757461
I realized it only zooms to 70mm in auto zoom mode. Manually it will zoom to 105mm. There may be something wrong with it, so I want to send it back to B&H and exchange.

... and get another that (by design) behaves exactly the same! You say that you had a similar problem with Nikon - perhaps you need to shift your perceptions of what is involved.

It is not the flash that determines the exposure, but the camera. Perhaps the bounce surface and distance, the maximum flash output, the no-flash ambient contribution, etc, are factors that need adjusting.

There are a whole bunch of things that could be happening here, depending on what metering mode you're in, what shooting mode, what/who you're shooting, and whether you mean the whole frame is underexposed, or just the subject. More information would help narrow it down.

The most obvious cause, especially if you're shooting with the camera in manual mode, is that the flash is firing at full power and it's simply not enough (when bounced) for the aperture and shutter speed you have selected. E-TTL is great, but it's not magic and can't make your flash put out more than 100% power If this is the case, flash exposure compensation will do nothing--it's already maxed out. You will need a wider aperture or slower shutter speed. If you're using a high shutter speed and high-speed sync, this is more likely than if you're shooting at sync speed, since HSS reduces the effective power of your flash, but it's still possible in either case.

My Canon speedlites do not zoom with a zoom lens if they are pointed upwards to bounce, they go into manual zoom mode automatically. If the Yongnuo does not do this, you should set it manually (or find out if it's defective).