Depth of field

The special focus length has some advantages for macro photography because the distance between lens and CCD is shorter. In this case, the ray's dispersion  makes depth of field as wider as appears by classical lens.
Here you can find some data of depths of field (in mm) of Dimage 7. There are also some DOFs measured by using additional lenses.
    DOF (mm) at aperture      

Focus (mm)

Focus

set to

9,5

8,0

5,6

3,5

Distance to

subject (cm)

Visible

area

Magnification

(ref to 35 mm)

200 120 cm 150 90 60 40 100 cm 20 cm 0,17:1
200 60 cm 70 50 35 20 50 cm 11 cm 0,32:1
200 macro 60 cm 65 50 35 20 50 cm 11 cm 0,32:1
200 macro 25 cm 10 7 5 3 13 cm 5 cm 0,7:1
200 macro + 2x 60 cm 10 8 6 4 25 cm 5,8 cm 0,6:1
200 macro + 2x 25 cm 8 6 4 2 10 cm 4 cm 0,87:1
200 macro + 6x 60 cm 4 3 2 1 13 cm 2,8 cm 1,25:1
200 macro + 6x 25 cm 5 4 3 2 8 cm 2,8 cm 1,25:1
200 macro + 50 mm 60 cm 1 0,8 0,5 0,3 3 cm 1,2 cm 2,92:1
200 macro + 50 mm 25 cm 1,5 1,3 1 0,6 2 cm 1,9 cm 1,84:1

To compare, some depths of field data of my old Tokina's 70 mm macro lens and extension tube at aperture 16 are here:

 

Focus (mm)

DOF

Distance to

subject (cm)

Visible

field

Magnification

70 macro + 50 mm 2,5 mm 3 cm 3 cm 1,17:1
70 macro + 60 mm tube 1,5 mm 4 cm 2 cm 2:1
70 macro + 60 +68 mm tube 1 mm 3 cm 1 cm 3:1

Depth of field with add-lens samples:

macro 200 mm

10_primerjave_makro_200_.JPG (23602 bytes)

macro 200 mm,

  add-lens 2x

10_primerjave_makro_200_predleca2x.JPG (23359 bytes)

macro 200 mm,

  add-lens 2x + 4x

10_primerjave_makro_200_predleca_2x4x.JPG (16422 bytes)