14 July 2011

Focus Bracketing or Photo Stacking

Focus Bracketing: (or Stacking)
Susan Brannon

This is useful with limited depths of field mostly used in macro photography where you can focus the subject at different positions.  Take several images of the same subject each with a different focus spot.  For example, take an image of a flower and let your camera automatically bracket your image.  You will notice that the image may be focused in the front (closest) to your camera, and blurred at the back.  Now, take that same flower, and bracket focus on the back of the flower instead, manually.  The front of the flower is blurred, while the back is in focus.

There is a term “focus stacking” that by taking a sequence of various parts of the subject in focus and combining them together to create the entire subject in focus.  This is not easy to do, because it requires delicate use of PhotoShop to combine the images!

Some tips:
1)  Focal length -  The longer your lens, the more shallow your depth of field is.
2)  Distance to the subject:  The nearer you are to your subject, the shallower your depth of field is, especially with a macro lens. 
3)  Aperture settings:  The more you open the aperture, the shallower your depth of field will be.

How do you do this?

A)  Use a steady tripod.
B) A macro lens, to get really close.
C) Super precision:  Lock your camera on your tripod, so you cannot move your camera. 
And rely on your in camera focus points to focus on different parts of the image.
D) Patience:  This process takes quite some time
E)  Post processing software, that can handle focus stacking.
F)  Create a file with layers, stacked on each in a linear arrangement.  Do not jumble the sequence of focused images.
G)  Align layers
H) Blend layers

Image below from Wikipedia:

Related lessons:
Aperture and f/16 Rule
Shutter Speed Basics

Depth of Field
Focused Bracketing or Photo Stacking 

No comments: