Abstract: An improvement of an inverted telephoto type wide angle lens system having, from the object to the image side a front lens group of a negative refractive power which is left stationary upon focusing, and a rear lens group of a positive refractive power which is shiftable for the purpose of focusing is disclosed. The improvement is characterized in that the lens system fulfills the following condition:2.65<.vertline.f.sub.F .vertline./f.sub.R <7.5wherein f.sub.F represents the focal length of the front lens group, and f.sub.F represents the focal length of the rear lens group.

Abstract: To determine a dimension of an article, a beam is directed at the article by means of a first mobile deflector so as to scan the part of the profile of the article comprising the dimension to be measured. Rays reflected by the article are orientated in the direction of at least one receiver by means of a second mobile deflector. The deflectors are angularly moved at different speeds. The positions occupied by two points related with the dimension are determined. The dimension is calculated with respect to these points.