Astrophysics (Index)About

focal plane tilt

(focal plane not perpendicular to the optical axis)

Focal plane tilt is a source of aberration (distortion) in optical instruments (such as telescopes) consisting of a focal plane that is tilted in relation to its intended or ideal attitude. Typically the intended focal plane is perpendicular to the optical axis. For a telescope symmetric around its optical axis, such a tilt represents a misadjustment or a flaw in construction. If the sensor can be aligned with the tilted focal plane, some distortion results, and if not aligned, then the entire sensor cannot be focused: there will be some direction across the image in which the quality of the focus is varying. Aberrations due to atmospheric effects can result in an approximation of focal plane tilt, and methods used to overcome this include adjusting the sensor-position to best match the resulting tilted focal plane or compensating through optics.

Focal plane tilt is sometimes deliberately used in (non-astronomical) photography, e.g., to bring your attention to one portion of the picture by degrading the focus of the rest of the picture.


(telescopes,aberration)
Further reading:
https://www.cloudynights.com/topic/580389-failing-to-fix-focal-plane-tilt-need-some-help/
https://astrogeartoday.com/camera-tilt-correction-made-easy-baader-planetarium-m68-tilter-review/

Referenced by page:
aberration

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