manually set power for pop up flash on 40D?

Started Jun 16, 2010 | Discussions thread
Jim N'AZ Veteran Member • Posts: 7,480
Re: manually set power for pop up flash on 40D?

ccm wrote:

Assuming the subject is live then yes a double flash is undesireable.

A hand over the popup or drop cloth...maybe even pcs of tape as a hinge with small cloth/card (similar to your device) would suffice. Does this actually work on a 40D? I don't know, I don't own one.

Yes, it works on the 40D. If you will look at my earlier post I included some pix demonstrating it being successfully used on my 40D.

I still think using a couple of Wein peanut (digital) slaves will work best. I use them and I don't have to worry about whether the preflash is going to bother me or not and with the Nikon SG-3IR visible light blocker (modified to fit on the Canon), I am good to go without fussing any further.
Regards, Jim

A quick experiment on my 30D:

Verify there is a preflash in manual shooting mode
-set second curtain synch in custom functions
-set shutter speed to be quite slow
-disengaged AF
-fired preflash with *
-activated shutter and watched flash go off

-tried same activity with AF on, half press shutter and hold, press * and then full depress to activate shutter.

Preflash activity is confirmed in manual shooting mode

Test if Preflash in manual shooting mode linked to ETTL.
-put different objects in front of popup like white card, hand etc.

Yes preflash is effecting ETTL. White background results in underexposed scene (flash dials back power), hand in more exposure, dark objects more exposure.

So the method of blocking the preflash must be consistent. Again, I don't own a 40D but I'm pretty sure this would work.

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