canon question - how to change exposure and flash exposure at the same tim

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sheridant

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Hi,

I have a canon 5d Mk2, and i've been trying to decrease my exposure while increase the flash exposure at the same time - in full manual

It doesn't seem to be possible - can it be done and if not - what's the alternative?

If I go into aperture priority mode, it automatically set's a very slow shutter speed , and the shutter priority mode forces the widest aperture (assuming the light is sufficiently low to need a flash)


Thanks
 
Firstly, flash isn't for when it gets dark. 95% of the time I use mine will be in full sun.

Anyway, back to the question, what flash are you using?

I always set flash power on the back of the gun itself, I think there's also a button on the top of the camera to set it, but it seems a very round about way of doing things to me.

Failing that, you could increase your shutterspeed and open up your aperture.

Increase your shutterspeed more than you open up, and obviously the ambient exposure will be less, but as you've opened up, you will be able to squeeze more power from your flash. You'll need to turn on high speed sync if you go above 1/200th.

You could also play about with your ISO, but that will affect both flash and ambient exposures.

:thumbs:
 
This can be done, in manual you need to set a shutter speed or aperture that will allow you to decrease the available light (although from your post you indicate that the available light is already quite low). Then if using an ettl flash you can increase the flash exposure by using the flash exposure compensation button on the 5DMk2.

If the available light is too high then yu may need to set High Speed Sync on your flash if available, although this does cut down on the amountof power you are able to use.
 
In Av mode, the default position with flash is to match the shutter speed with the ambient light (as you have discovered). It you want the camera to set the max x-sync speed instead, change the setting in custom functions.

The easiest way to adjust flash exposure is with +/- compensation on the gun, and adjust ambient exposure on the camera. I think you can do both on camera, but I find the other way easier and more logical. If you change settings on the gun, it will override any changes you've made to flash exposure on camera.
 
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