# LX3/LX5/LX7 - Sensors and Hyperfocal Distances and Depths of Field

Started Sep 24, 2012 | Discussions thread
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LX3/LX5/LX7 - Sensors and Hyperfocal Distances and Depths of Field

Had not realized that the LX7 has a somewhat smaller sensor than the LX3 and LX5 so I had a look:

http://www.dpreview.com/previews/panasonic-lumix-dmc-lx7

From that information (and Panasonic's statement that the LX3/LX5 image-sensor pixel-pitch equals 2.025 Microns), I derived the following information (sensor dimensions for 4:3 aspect-ratio mode):

LX3/LX5

Pixel-pitch=2.025 Microns. Active sensor dimensions are 7.3872mm x 5.5404mm. Active sensor area=40.9280mm. Minimum Focal Length=5.1mm. Circle of Confusion diameter=6.403 Microns (based on 30 Micron full-frame COC diameter, 8"x10" size viewed at 25cm with 20/20 visual acuity)

Hyperfocal Distance [HFD in Meters] = ( 4.062 ) x ( Z^(2) ) / ( F )

Hyperfocal Distance [HFD in Feet] = ( 13.328 ) x ( Z^(2) ) / ( F )

where:
Z is Zoom Factor;
F is F-Number.
.

LX7

Pixel-pitch=1.846 Microns. Active sensor dimensions are 6.7342mm x 5.0507mm. Active sensor area=34.0124mm. Minimum Focal Length=4.7mm. Circle of Confusion diameter=5.837 Microns (based on 30 Micron full-frame COC diameter, 8"x10" size viewed at 25cm with 20/20 visual acuity)

Hyperfocal Distance [in Meters] = ( 3.785 ) x ( Z^(2) ) / ( F )

Hyperfocal Distance [in Feet] = ( 12.417 ) x ( Z^(2) ) / ( F )

where:
Z is Zoom Factor;
F is F-Number.
.

Note: The formulas for Hyperfocal Distance above are very close approximations when the Camera-Subject Distance (between the front nodal-plane of the lens-system and the plane-of-focus) is significantly larger than the (actual) Focal Length multiplied by Zoom Factor. This is true in all but the very closest-up of of shooting conditions - so they can be considered to be accurate .
.

Calculating the Depth of Field from the Hyperfocal Distance

Units of either Meters or Feet can be used (as long as the same units are used when entering HFD and D ). HFD is the Hyperfocal Distance (calculated from the above formulas). D is the Camera-Subject Distance (between the front nodal-plane of the lens-system and the plane-of-focus).

An approximation valid (with not more than 11% error) when D is equal to or less than 1/3 of HFD

Depth of Field [DOF] ~ ( 2 ) x ( D^(2) ) / ( HFD )

A precise formula valid when D has a value less than the HFD ( undefined when D => the HFD ):

Depth of Field [DOF] = ( 2 ) x ( D ) / ( ( HFD / D ) - ( D / HFD ) )

Panasonic Lumix DMC-LX3 Panasonic Lumix DMC-LX5 Panasonic Lumix DMC-LX7
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