Plane of focus
The point in a camera where all the light rays converge, forming a sharp image. In a camera, this corresponds to the film plane.
[edit] Plane of focus
Because focus depends on the distance between lens and sensor/film plane, focus in the space in front of the camera is not on a point but on a plane which is parallel to the film plane.
1) Not being in the plane of focus. Every photo has a plane of focus where sharpness is maximized. Obviously the subject must be in this plane to be sharp.
They use camera movements known as tilt and shift to alter the plane of focus. The plane of focus is usually parallel to the film.
Such a subject has a single, flat plane of focus, extending from near to far horizontally from the photographer.
At normal subject sizes, depth of field extends roughly one third in front of your plane of focus and two thirds behind it, but at macro sizes, it becomes closer to fifty-fifty, ...
Your plane of focus is very shallow — just a fraction of an inch. So you have to make another decision: Exactly what part of the flower do you want to be in sharp focus? The pistil? The stamen? A petal?
The inability to bring light of all colours to the same plane of focus is known as chromatic aberration. Light refraction is a function of wavelength, and as such each colour is normally brought to as lightly different plane of focus.
It can't swim away and the plane of focus is easy to control. But what if you don't have the right size tube and framer installed on your camera?
The area in front of and behind the plane of focus in the scene which is acceptably sharp (for intended enlargement). Tip: a little more depth requires a lot more light (for smaller Stop) or a wider-angle lens.
Among the wide-angle lenses discussed here, this one provides the best corner-to-corner sharpness for landscape on the D3X as one can adjust the plane of focus to suit the composition.
Similarly, the original subject in the center "C", will still be at the original focus distance "d" from the lens, but the plane of focus at the edge of the frame will be at a distance of x (= d/cos(theta)) from the lens.
The inability of a lens to bring all light wavelengths (particularly red & blue) into the same plane of focus, thus causing overall blur. Usually found in regular large-aperture telephoto and super-telephoto lenses.
Tilt-and-shift lenses are particularly useful for this type of work. They allow the plane of focus, and therefore the depth-of-field plane, to be tilted to give superior sharpness from the front to the back of the image.
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Curvature of field
Lens aberration causing a curved plane of focus.
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-Curvature of field - lens aberration causing a curved plane of focus.
-Cut film - negative film available in flat sheets. The most common sizes are 4x5, and 8x10 inches.
-APO (Apochromatic) - the ability to bring all colors of the visible spectrum to a common plane of focus, within close tolerances. It usually refers to a lens with such superior color correction.
Focus lock is still a bit of a hit or miss since the photographer may unintentionally move the camera away from the plane of focus. For macro work you are shooting manually anyway (or should be).
Before trying focus lock I would try: ...
While separated by only millimeters, those in front and behind the plane of focus fell out of the depth of field range. Note that the back of the blossom is totally out of focus.
But if the camera consistently and erroneously brings the plane of focus ahead of the film surface (or image sensor surface on a digital camera) then you've got a problem, since everything will look slightly out of focus.
Also, any close-up frame or pointer will show you precisely the plane of focus of the system. Briefly, if a subject is in the plane of the frame, or right at the tip of the pointer, it will be in focus.
This is mainly used to correct converging verticals or horizontals. The tilt movement allows the lens to be rotated or tilted in relation to the sensor, this allows the photographer to adjust the plane of focus and take greater control over depth of ...
 See also: Focus, Plane, Photograph, Lens, Camera
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