Wednesday, May 22, 2013

Focus stacking again

Bert found this cool article about macro focus stacking.
(That is, the use of several exposures with slightly varying focus being combined in the computer for greater depth of field. The super-narrow depth of field has always been the bane of macro photography, so it's very welcome there.)

The Conan of frogs on his horned mythological steed.

... We are not here, you are having a dream...

"Who, me, officer?!"


Ken said...

I've used this with fungi, for which it is easy as they don't move. The main other problem is that the light has to be consistent. Although cameras will compensate for changing exposure they can't for different levels within a photograph.

Some people are really getting into it. They control their cameras electronically so they can alter focus a set amount and automatically.

Anonymous said...

This comment "By using the technique known as focus stacking — combining several images taken at different depths of field — " ... is not accurate. The dof remains constant. The lens to subject distance is systematically stepped through the extremes of focus. The software extracts the bits that in in focus and combines them to produce the final image.

Eolake Stobblehouse said...

You're quite right.

Eolake Stobblehouse said...

I would guess that automatic control of the camera in the procedure would be almost a necessity, given the tiny tolerances and changes, and the living subjects.

Ken said...

It can be done OK focussing by hand, provided that extreme magnification is not required, and a bit of care is taken. The method works fine if the shift in focus is too short, only is a problem if it is too long, so basically the focus is just nudged a bit between each shot. At life size I can get about 20 shots in a cm, but that requires a small aperture. Some photographers use wider apertures and therefore require lots of finely spaced images.

Almost nobody does living subjects, because it requires subjects that don't move. The images on the website you referenced are a mix of focus stacking and traditional.