closest point on optical axis with an image that has „acceptable sharpness“

Where CoC is the Circle of Confusion (the largest accepted Airy-disk) in **Millimeter**.

Alternatively, we can express the NearPoint using the magnification M :

**greyscale**Sensor mit 2.2 pixel pitch, we can use the pixel diagonal as CoC for crisp images, say

A 5 Mega lens with f=7.2mm focal length and F-stop F2.4, focused to an object distance of 100mm then has a far point of

und einen Nahpunkt von

and thus

**greyscale**Sony Sensor with 3.45 pixel pitch, we can choose as CoC the diagonal of the pixel for crisp images, say

A 5 Mega lens with f=7.2mm focal length and F-stop F2.4, focussed to 100mm then results in

mm

and a nearpoint of

thus we get

**color**sensor instead we can use for crisp images. For the two sensors above we then get:

**same**sensor) you get the

**same**FOV (then from a different distance) this results in the

**same**DOF !!!

see also https://www.optowiki.info/blog/can-i-increase-the-dof-by-changing-the-focal-length/

**keep the working distance and the pixel size**while reducing the sensor size, but then we lose resolution (because less of the same size pixels fit on the now smaller sensor)

The DOF is then, thus focussing to the hyperfocal distance results in the largest possible DOF.

Yet another way to express the Near-Point is to use the Hyperfocal distance H :

If the lens is then focused to some object distance OD, this OD can be expressed as fraction of H :

or

Then the near point is

,

the far point is

and the Depth of field is

Therefore from

we get

.

This means however, that

and therefore,

**For we get**

So, with

and

we get

**For we get**

So, with

and

we get

Therefore by decreasing the OD by factor 2, the DOF decreased by factor 4.

or, equivalent :