Monday, September 13, 2021

Using Depth of Field in Painting

What attracted me about this view of the marina at Cold Spring, NY was the “keyhole view” down the ramp to the water.


I also liked the opportunity to suggest depth on the Z-axis by selecting where to put detail. The fine details of railings and wires are only in the middle ground. The front of the vehicle on the right is painted a little out of focus.

7 comments:

Forrest said...

Can you elaborate on the Z-axis, etc. Sorry, I feel silly, but I want to make sure I understand which direction that is. :) For that matter, which axis should we be concerned about in a composition with this depth of field technique in mind?

James Gurney said...

Forrest, good question. Usually I think of the picture plane as defined by the X and Y axes, and the dimension perpendicular to those two lines (close to far from your eye) would be the Z axis.

Kalp said...

Interesting. I thought Z-axis was referring to the vertical plane, like physically from the ground skyward. That's mostly because I usually think of geometry in relation to Computer Graphics (CG). Is there any particular merit of imagining space in the way you described, especially when it comes to painting?

Kalp said...

Interesting. I thought Z-axis was referring to the vertical plane, like physically from the ground skyward. That's mostly because I usually think of geometry in relation to Computer Graphics (CG). Is there any particular merit of imagining space in the way you described, especially when it comes to painting?

James Gurney said...

Kalp, thanks for pointing out that I'm using the "Z" term in an unorthodox way. I'm defining the term Z-axis as a normal of the plane defined by X and Y, independent of gravity. In other words, Z is the vector perpendicular to the picture plane, whether the picture is sitting flat on a table or vertical on an easel.

Pierre Fontaine said...

When discussing a flat painting, the two dimensional cartesian coordinate system is used where X and Y describe the physical plane of the painting. Z isn't really used but could be invoked to describe the implied depth of the image as Mr Gurney does here.

When discussing a 3 dimensional item (as used by CAD and 3D programs), the same cartesian system uses X to describe the left/right horizontal coordinates, Y to describe the depth (closest to farthest) and Z to describe the vertical/height/depth coordinates. However, I have seen older 3D software that continues to use Y for the height/depth description and Z for the depth description.

Unknown said...

In photography, pinhole camera models and projections, Z-axis is used to signify the depth of field.

Mr Gurney's notation is consistent with how perspective is represented in academic notes today.