Focus stacking is a technique to get an extended depth of field in photographs where the maximum depth of field* is not possible using the popular photography techniques.
* ‘Depth of field’ is the acceptable range of effective sharpness of the subject on the axis of the lens.
We know that the maximum depth of the field is possible,
- By using smaller aperture diameters (higher f numbers like f32/f22/f16
- By using smaller focal length lenses
- By shooting from a longer distance
- By using cameras with smaller sensor size
Despite of using the above techniques, some times we cannot show the subject sharp all through.
Particularly when shooting from a closer distance, to get the maximum sharpness spreading all through the subject area, ‘focus-stacking technique’ is used.
This technique is useful for shooting small objects using macro lenses / product shots / jewelry shots / food shots where the subject demands total sharpness.
This is nothing but shooting a sequence of images focusing at various planes and then merging them carefully in the post production process using an image processing software. In the image shown here, the milk and cookies at different planes are focused individually.
The three individual images where the points of focus are different give a different range of depth of field. Composting all the three images into one by erasing the less sharper areas of the individual images using layer masking technique to retain only the sharp areas gives complete sharpness all through the image. This gives a feel of extended depth of field, which is not otherwise achievable.
Note: The camera needs to be on a tripod and the subject must be stationary to take control of composition.
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