Faulty tutorial?

[jamesino]

While reading about DOF, I came across this tutorial:

http://www.trustedreviews.com/digit.../Digital-Photography-Tutorial-Focul-Length/p4

It states that "...due to the increased depth of field in the wide angle shot, the background, although apparently more distant, is much sharper." And has two pictures to prove it.

However, this does not concur with every other tutorials that I have read. My explanation for the photos that he shows is because he decreased the aperture size (increase f number) in order to get the background in focus in the second shot.

Who is right?

EDIT: Clarified "decrease" aperture.

 

[JerryPH]

Numerical increase in the aperture number (DECREASE in the physical aperture), the DOF increases.

 

[Sideburns]

when you make the aperture smaller, the DOF is larger...this is true. But it's also true that a wide angle lens has a deeper DOF ability. This is one reason why photographers use a wide angle lens for landscapes...they can get the whole darn thing in focus.

 

[jamesino]

Aren't the only factors that affect DOF the focal distance and the aperture? Since the author is decreasing focal distance because he/she is keeping the subject the same size, shouldn't the background be blurrier?

 

[Helen B]

While reading about DOF, I came across this tutorial:

http://www.trustedreviews.com/digit.../Digital-Photography-Tutorial-Focul-Length/p4

It states that "...due to the increased depth of field in the wide angle shot, the background, although apparently more distant, is much sharper." And has two pictures to prove it.

...

That's correct, in a way. The distant parts appear less blurred than they would be if a longer lens had been used because they are less magnified. If the background was magnified to the same extent that you would see with a longer lens, the amount of blur would be equal.

Best,
Helen