Tuesday, March 12, 2013
Unleash Unlimited Depth Of Field
Use stacked focus to create images that overcome the bounds of optics for your macro shots and more
Like many things we now do in photography, there's a capture portion and then a processing portion done with specialized software. I'm presenting four examples and how to apply the technique to each.
Overall Extended Depth Of Field In Close-Ups. This is the most common use for the stacked focus technique. We use it for compositions that are treated like miniature landscapes with sharpness throughout the composition. It's not appropriate for subjects that are isolated against distant backgrounds. (For those compositions, see the Extended/Selective Depth Of Field example.)
Because stacked focus gives us unlimited depth of field (starting with the near limit a lens can focus at), we no longer have to take depth of field into consideration when composing. This gives us creative freedom to work from any angle.
Here's the step by step for capturing the images:
1 Securely mount the camera on a sturdy tripod. Lock it down well.
2 Set the camera to manual focus, aperture priority, mirror locked up, and use a two-second self-timer or remote shutter release. (Vibrations are magnified in close-ups; if either the camera or subject moves during the capture process, start over.)
3 Compose your shot with the focus at the closest part of your composition.
4 Make your first capture.
5 Carefully shift the focus back one depth of field zone and make your next capture. I simply estimate the depth of field I'm getting by zooming in on the LCD image from a test capture. The more images you make, with smaller increments, the sharper your results will be. Don't be frugal here; the last thing you want is to process the image and discover you skipped over zones, resulting in bands in and out of focus. The higher your magnification, the more images you'll need to make. Something the size of a coffee cup may only need three or four captures, while something the size of a postage stamp may require 30.
6 Continue to shift the focus and make captures until you've worked your way to the back of the composition. It's not necessary that they be done in even increments. If there are very important details you want exceptionally sharp, you may want to do extra captures precisely focused on those.
While it's possible to process the stacks with other software, including Photoshop, Helicon Focus produces the best results I've seen, with the most control. It's also extremely easy to use. I would recommend the Pro version. At $200, it's one of the greatest bargains in photography. As I ask my students, what would you be willing to pay for a lens that gave you infinite depth of field at any focal length?
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