Looking for information on the relation of the aperture and focus distance

[KmH]

The DoF tutorial on that site is linked to in post #3.

 

[bratkinson]

To my senior-citizen mind, I tend to think of depth of field in relation to aperture size as 'more DOF/smaller aperture' or less DOF/larger aperture, rather than thinking 'f/2.8 at 10 feet is ... f2.8 at 20 feet is...' etc. As I tend to shoot mostly events, there really isn't time to go through all those mental gymnastics. I'm more concerned with the trade-offs in the exposure triangle first to get the correct exposure, then to adjust as needed to get 'more' or 'less' DOF starting from, say, f5.6 or whatever settings are then set.

 

[KmH]

In my senior citizen mind, I visualize the DoF changing as I move closer to or further away from my point of focus.

I believe a main reason so many people have difficulty fully understanding DoF is because they only think of DoF in terms of lens aperture, and are not fully aware of the other factors that also have a big influence on DoF.

So the 4 DoF calculations above tend to demonstrate that, and to address the myth that longer focal lengths produce shallower DoF.

 

[AaronLLockhart]

Bokeh is not adjustable. Bokeh and DoF are not the same thing.

I've heard not only you, but several photographers say this during mytme here at TPF. However, within reason, part of these statements are not true.

"Bokeh is not adjustable."

Really, then why as you open your aperture, speed up your shutter, maximize your focal length, and get closer to your subject, does the amount of Bokeh increase???? (Don't start mouthing Depth of Field changes, I'm about to get to that.)

It can be adjusted. The same way that everything else you do in photography gets adjusted. It is a changeable factor, and is VERY adjustable. I can do this with an iPhone by simply moving the phone closer and further from my subject. Which is the same thing as an adjustment, as I am adjusting my distance to subject.

"Bokeh and DoF are not the same."

Maybe not in direct terms. However, they are in direct relation to each other, and the DoF directly results the amount of Bokeh will be present in the photograph. The shallower the DoF, the more bokeh occurs. The deeper the DoF, the less bokeh occurs.

Let's not forget the definition of the word, "Bokeh." Bokeh is a word derived from the Japanese word "boke," which means "blur." The term is used to describe the aesthetic quality of the blur in the areas that are outside the depth of field, or outside the "in focus areas."

They are in direct relation, and you cannot get bokeh, without a depth of field adjustment.