Flash shadow...what did I do wrong?

Wilt wrote in post #6332440
This is a widely spread fallacy! If you use a DOF calculation program, one finds that a macro distances the DOF is about 50:50, at a single specific distance it is 35:65 as stated, and that it can in fact go more than 5:95 So if you merely follow the simple rule of thumb, your DOF is quite out of whack!

At the above stated 5 feet/55mm/f8, the DoF is 46% front, 54% behind, so 35/65 is definitely not a 'rule'.

DoF was also about 9 inches. Moving up to f/11 gives nearly 13.

Lots of useful info here, much appreciated.

Wilt wrote in post #6332440
This is a widely spread fallacy! If you use a DOF calculation program, one finds that a macro distances the DOF is about 50:50, at a single specific distance it is 35:65 as stated, and that it can in fact go more than 5:95 So if you merely follow the simple rule of thumb, your DOF is quite out of whack!

Okay, so the exact math may be a little out. My point is still perfectly valid, there is still more of the DoF behind the focus plane than in front (we're talking portraits not macro, so the 50:50 isn't valid in this case).

My comment was that focusing on the rear child will NOT make it more likely that both will be in focus, for the reason stated above. The exact percentages are not critical to the principle.