It is commonly held that wide angle lenses have greater depth of field than normal lenses, and this is true of one photographs from the same object distance. However, if one moves closer with the wide angle lens so that the subject is framed in the same way (equal magnification), depth of field is the same (see
Paul van Walree).
With symmetrical macro lenses, depth of field is the same for a given magnification regardless of focal length. However, with asymmetrical lenses where pupillary magnification is less than one, depth of field for a given magnification is greater with the longer focal length lens (see above link).
This is an unexpected (for me) benefit of my new Sigma 180 f/2.8 macro lens. The pupillary magnification can be estimated by viewing the lens diaphragm from both the front and back of the lens. The ratio front to back is considerably less than unity, so I would expect greater depth of field than with my 100 mm macro where the pupillary magnification is closer to unity.
Has anyone noted this effect in the field with macro photography?
Regards,
Bill
