No need for personal attack here. I have never claim any sacred knowledge as you claimed. All my statements are accurate(may be beyond your understanding??). We started out with focusing between rangefinder and DSLR film camera( assuming within in the capacity of both cameras) Then you keep on changing and get tilt-shift lens involved. . Now it is MACRO photography. You should know that rangefinder camera are not built for these task. Just go dig up the DOF formula for normal photography, It only involve focal length of the lens, aperture, and circle of confusion. There is no magnification involved.
Since you started personal attack, that is the end of this discussion in order to keep this website being civilize. Just be cool and keep calm and take some tranquilizer.
Focal length
is an expression of magnification! That's what a lens does when it refracts light! It magnifies it! For most lenses, the magnification factor is less than 1.0, but if an image of the subject on the sensor/film is one half the size of the actual subject, then the
magnification ratio is 1:2 or 0.5X. That's still a
magnification factor.
The DoF formula also includes subject distance in addition to focal length, aperture, and CoC. This is because subject distance also affects magnification!
If a lens has a reproduction ratio (i.e.
magnification) of 1:1 at a MFD that is equal to 4X the focal length - at "unity" a single element thin lens with 100mm focal length (as measured when focused at infinity) is 200mm from the imaging plane and the subject is another 200mm beyond the lens, or 400mm from the imaging plane - the size of the subject as projected onto the imaging plane will equal the the size of the subject. Both the subject and the virtual image of the subject will have the same angular size as measured from the lens. If the subject is moved further away from the camera and the lens is moved closer to the imaging plane to bring the subject into focus, the size of the subject is reduced in the virtual image. That is, the virtual image of the subject is now smaller than the actual size of the subject because both are still the same angular size as measured from the lens but the lens is much closer to the imaging plane (sensor/film) than to the subject.
For example, when we take a 300m lens and fill the long side of a 35mm/FF with a person 6 foot (1.829m or 1829mm) tall standing at a distance of 49 feet 9 inches from the camera's imaging plane, the magnification ratio is 35mm/1829mm, or 1:52.25 for a
magnification ratio of 0.019X. This occurs because both the subject and the virtual image of the subject projected onto the the camera's imaging plane (film/sensor) have an angular size of 6.9° as measured from 300mm in front of the camera's imaging plane.
From
wikipedia:
Magnification is the process of enlarging the
apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in size, sometimes called
minification or
de-magnification.
Also from
wikipedia:
The
angular diameter,
angular size,
apparent diameter, or
apparent size is an angular measurement describing how large a
sphere or
circle appears from a given point of view.
Everything about DoF is based upon the angular size, as measured by the viewer's eyes, of the largest blur circle that will not be distinguishable from a single point.