BISECTING ANGLE

 The film is placed as close as possible to the surface.
 Central ray is directed perpendicular to the imaginary bisector.
 Advantage – shorter exposure time, more patient acceptance cos we don’t need a beam aligner ring.
 Disadvatage – image distortion/ magnification is possible. Angulation problems maybe, coz beam aligner right.


PARALELLING BEAM

 It is easy to place using a film holder.
 Central ray is perpendicular to both recptor & long axis of the tooth.
 To maintain the parallelism between the object & the film, - INCREASE TARGET TO OBJECT DISTANCE *
 Advantage – more accurate & Simplicity (no extra calculations required)
 Disadvantages – patient discomfort.