DOF question: I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this. My question is, shooting...

Finch585 Loc: Northern California

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

Wabbit Loc: Arizona Desert

Finch585 wrote:

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

Hey Doc ..... "it's subjective"..... "in the eyes of the beholder" ..... based on what's in front or in back in combination with your focus point .....

Nikonian72 Loc: Chico CA

Theoretically, DoF extends from 1/3 in front of plane of focus, to 2/3 behind PoF. Most noticeable at largest apertures.

Searcher Loc: Kent, England

Finch585 wrote:

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

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

If you have not seen this calculator before then I suggest you bookmark it. With a few experiments it will give you a good insight into DoF.

Wendy2 Loc: California

If you want the background blurred, get closer to the subject that you want in focus.

Nikonian72 Loc: Chico CA

Finch585 wrote:

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

First, your Plane of Focus or Point of Focus ("focal plane" ) should be on your subject. Contrary to your question, there should be no distance from "focal plane" to subject.

The closer your camera is to subject, the more narrow your DoF. At Minimum Focusing Distance, macro-photographers often work with just millimeters of DoF, even at f/16.

GHK Loc: The Vale of Eden

Finch585 wrote:

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

I'm sorry, but you don't seem to have asked a question.
GHK

JudyTee23 Loc: Eastern U. S.

Nikonian72 wrote:

Theoretically, DoF extends from 1/3 in front of plane of focus, to 2/3 behind PoF. Most noticeable at largest apertures.

Theoretically? Prove it.

The truth is,for any given focal length, the one third/two thirds "rule" holds true over only a small range of distances.

ziggykor Loc: East Texas

There's no set answer to this except the statement the photographer is trying to make. Three things impact depth of field: Camera to subject distance, aperture and lens focal length. Experiment with your equipment and learn how it responds to a given shooting situation. Every lens is different!

jimmya Loc: Phoenix

Finch585 wrote:

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

I don't understand why so many want to make this so complicated. It's really simple. The largest aperture you have on a given lens, close to the subject and fire. If you think f/3.5 for example will be over exposed then set your aperture at the largest and let the camera make the shutter speed decision... couldn't be simpler. To me all this fuss won't make a bit of difference if you know how to properly operate your lens.

Below, for example, was shot with my Canon 28-200 lens in bright sun and I still managed to get a short DOF.

Wabbit Loc: Arizona Desert

GHK wrote:

Finch585 wrote:

I've read a lot here and elsewhere, about how to create shallow DOF, (FL, aperture, distance), but I'm still not clear on one aspect of this.

My question is, shooting with an 85mm lens on a DX body at f/1.8, which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

thanks in advance.

Jeffrey

I'm sorry, but you don't seem to have asked a question.
GHK

Hey Doc ..... he did ask a question, maybe poorly worded, but he asked just the same ..... and I'm the only one so far that's attempted to addressed it .....

..... here's his question and I quote

which affects shallow DOF more, the distance from focal plane to subject, or distance from subject to background to blur?

Wabbit Loc: Arizona Desert

jimmya wrote:

quote=Finch585 I've read a lot here and elsewhere... (show quote)

Hey Doc ..... then you don't understand the ops question .....

..... the poster is new to this, not such a dumb question actually, this means he's trying to grasp the concept .....

lightchime Loc: Somewhere Over The Rainbow

JudyTee23 wrote:

Nikonian72 wrote:

Theoretically, DoF extends from 1/3 in front of plane of focus, to 2/3 behind PoF. Most noticeable at largest apertures.

Theoretically? Prove it.

The truth is,for any given focal length, the one third/two thirds "rule" holds true over only a small range of distances.

Theory is like horse sense - it varies from horse to horse. As such, the 1/3- 2/3 rule is a nice guideline, but varies. It is like the rule of thirds - a nice guideline that doesn't work as often as it does. At least in theory.

These limiting rules are like statistics: 87.2 percent of statistics are made up on the spot and they can be made to lie 100% of the time.

To go further, this rule reminds me of the sunny 16 rule. I sure works. But you do not need the rule if the battery on your digital camera is dead. Come to think of it, if your batteries are alive, your meter should work. That sort of diminishes this rule also. A nice beast, but one of legacy. As we consider these rules and others, we should keep in mind what Voltaire had to say - all generalizations are false, including this one.

rocar7 Loc: Alton, England

Nikonian72 wrote:

quote=Finch585 My question is, shooting with an 8... (show quote)

The focal plane is where the sensor is, and is therefore behind the lens. Most cameras have a mark, which looks a bit like a Plimsoll line, which indicates exactly where the focal plane is. This is of little use to most of us, and is only really going to be used by laboratory technicians.

DoF varies with three things, lens focal length, aperture, and distance from camera to subject. As a generalisation, to get a shallow DoF use a relatively long focal-length lens, as wide an aperture as possible, and a short camera-to-subject distance. The sensor size also has an effect, so you will get a shallower DoF with a full frame camera.

GHK Loc: The Vale of Eden

rocar7 wrote:

quote=Nikonian72 quote=Finch585 My question is, ... (show quote)

There is confusion of terminology here between the point (plane) on which the camera is focussed, which is in front of the lens, and the focal plane, which is within the camera and is where the sensor/ film should be.
GHK