Depth of Field..

[MuahMan]

I know when I want the background blurred out I put on my 50mm 1.4 and shoot it wide open. My question is this, besides aperture. What else affect DOF/Bokeh. Should I be getting closer to the object or further away?

[SS904]

Closer and it depends on the focal length of the lens how much closer.

Here's a handy little calculator.

Depth of Field Table

EDIT:

This one is easier to use...

http://www.dofmaster.com/dofjs.html

[DUCeditor]

Another thing to remember is that do not have to focus on the subject. If the inherent depth of field of the lens (focal length and maximum opening) does not adequately soften the background sometimes inherent DOF is enough that you can slightly front focus.

Do test shots to see how much latitude you have or run a series with the main subject in focus and then front focusing progressively in steps. Then choose the most effective shot.

-don

[Leary Blaine]

I've been wondering about this, as well. DUCeditor, it sounds like you're advocating a MANUAL approach, focusing the focus (as it were) somewhat/somewhere in front of the subject, to place the subject toward the "rear" of the in-focus envelope.

Vero?
Va bene per me. Perche no?
Grazie!

[Bill A]

Originally Posted by MuahMan

...besides aperture. What else affect DOF/Bokeh. Should I be getting closer to the object or further away?

The closer you are physically to your subject, the narrower your DOF will be at any given aperture setting.

[Mr. Clean]

aperture
focal length
distance from lens to subject
distance from subject to background

All effect DOF!

For example, on your 50 if you want less DOF, move closer to your subject. But sometimes you want a greater depth of field while still getting a nice out of focus background - move your subject further away from the background.

[DUCeditor]

Originally Posted by Leary Blaine

I've been wondering about this, as well. DUCeditor, it sounds like you're advocating a MANUAL approach, focusing the focus (as it were) somewhat/somewhere in front of the subject, to place the subject toward the "rear" of the in-focus envelope.

Vero?
Va bene per me. Perche no?
Grazie!

Exactly so. Recognize that acceptable focus depends in part on display size (linear dimension). That is true for everything but exact focus. Supposedly acceptable depth of field is simply someone's judgment based on a predetermined image size. The same is true for subject focus. I.e., charts and graphs can be helpful but they are just guidelines not laws.

And when you say "manual" approach, yes, but more accurately a photographer (not camera) chosen point of focus. Who physically moves the lens elements is not the important thing, just how far. ;-)

-don

[knumbnutz]

Originally Posted by Mr. Clean

For example, on your 50 if you want less DOF, move closer to your subject. But sometimes you want a greater depth of field while still getting a nice out of focus background - move your subject further away from the background.

Good points Everyone.
Also adding to this some lenses produce better bokeh if the distance to the background is tested.
That is to say, I shot a photo of a small flower in the middle of some grass and the lens (nikon D700+70-200 VR II) produced horrible bokeh of the grass.
It was almost similar to the nervous donut style of a mirror lens.

But move the grass closer or further away and it changes, even though in every instance it was blurry.

Bokeh quality is a property of the lens.

I also had a Pentax K20D + 50-135 with me and the bokeh from that on the same subject was stunning. It is almost unfair to compare though, the 50-135 does produce some of the best bokeh FWIW and of course the system is not FF like the nikon.

Cheers Neil