in the first embodiment as seen in fig1 , on a center biconcave rod lens main element ( 11 ′), which is symmetrical with respect to the center plane ( 100 ) that is perpendicular to the optical axis , biconvex lens elements ( 12 ′, 13 ′) are cemented to both sides , while the two outer rod lenses ( 20 , 30 ) are uncemented , identical , biconvex , and arranged symmetrically with respect to the aforementioned center plane ( 100 ). in addition , the center rod lens ( 10 ′) is longer than the two outer rod lenses ( 20 , 30 ). these outer rod lenses are , according to the invention , vertex - to - vertex adjacent on the center connecting rod lens ( 10 ′). a distancing tube , to distance the individual lenses ( 10 ′, 20 , 30 ) on the radial outside of these lenses , is thus not provided . in this embodiment and those that follow , all lens elements are of an optically homogenous material and all optically active surfaces ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ) of all indicated rod lenses are spherical . this embodiment has the advantage that the two outer rod lenses ( 20 , 30 ) can be manufactured as single pieces and identically , and the center rod lens main element ( 11 ′) can be connected in a simple manner with the lens elements ( 12 ′, 13 ′) of the center lens ( 10 ′) that are turned outward . embodiment 1 can , for instance , be produced according to the following table : this embodiment can be modified as a second embodiment , as shown in fig7 , so that the center symmetrical rod lens main element is produced as biconvex element ( 11 ), and meniscus elements ( 12 ″, 13 ″), rather than convex lens elements , can be cemented to it . the center rod lens main element in this case can advantageously be produced similarly or even identically to the outer lenses . according to a third embodiment , with both aforementioned embodiments it is also possible to produce the center lens ( 10 ′) to be approximately of the equal length as the outer lenses ( 20 , 30 ), for instance 90 percent of their length , instead of with a greater length . this has the advantage that the vignetting is reduced , for instance by a preselected percentage , than when the center lens is longer than the outer lenses . other similar embodiments can be derived from the previous three embodiments as a fourth embodiment , illustrated in fig4 , 5 , and 6 , in that the outer rod lenses ( 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ), rather than as one piece , are constructed like the center one ( 10 ′) as connecting rod lenses ( 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ); that is , both outer rod lenses ( 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ) are cemented on the side turned inward and / or on the side turned outward , symmetrical to one another with respect to a center plane ( 100 ) of the image transmission system with lens elements ( 22 ″, 32 ″, 23 xx , 33 xx ). these lens elements ( 22 ″, 32 ″, 23 xx , 33 xx ) can be positive or negative meniscus elements ( 22 ″, 32 ″, 23 xx , 33 xx ), or biconvex lens elements , depending on whether the rod lens main element ( 21 ″, 31 ″; 21 xx , 31 xx ; 21 ″ xx , 31 ″ xx ) of the outer rod lenses is biconvex , biconcave , or convex - concave . through these modifications — at an increased manufacturing cost — it is possible to reduce the image curvature advantageously . according to a fifth embodiment , as shown in fig2 , the rod lens system , in addition to a center rod lens ( 10 ) that is symmetrical with respect to its center plane ( 100 ) that is perpendicular to the optical axis , includes two outer connecting rod lenses ( 20 ′, 30 ′), which are symmetrical to one another with respect to the aforementioned center plane ( 100 ) and whose main elements ( 21 ′, 31 ′) are convex on the side turned outward and concave on the side turned inward . the center rod lens ( 10 ) here is biconvex and symmetrical but not cemented , and thus of one piece . as described above , it can be essentially of the same length as the outer rod lenses ( 20 ′, 30 ′) or somewhat longer , according to a preferred embodiment a maximum of 1 . 5 times as long as the outer rod lenses ( 20 ′, 30 ′). on each of the two identical outer rod lens main elements ( 20 ′, 30 ′) one biconvex lens element ( 22 ′, 32 ′) is cemented on the side turned inward . here too , as in all the following embodiments , the two outer connecting rod lenses ( 20 ′, 30 ′) are vertex - to - vertex adjacent on the center rod lens ( 10 ), making distancing holders superfluous . an advantage of this embodiment is that a lens element ( 22 ′, 32 ′) is cemented only on one side of the connecting rod main elements ( 21 ′, 31 ′), which involves a simpler manufacturing process , especially concerning the mounting of the main element . this embodiment can be modified to create a sixth embodiment , in that the outer rod lens main elements are produced as biconvex instead of convex - concave , and meniscus elements are cemented to them instead of convex lens elements . the center rod lens main element here can be produced as similar or even identical to the outer lenses . an advantage of this design is that the optically active surfaces of all rod lenses , that is of the two main elements of the outer rod lenses and the center rod lens , are convex and possibly identical ; in other words , they can be produced together . the following modifications are possible to the fifth and sixth embodiments : as a seventh embodiment , the center rod element ( 10 ′), as in fig4 , rather than being of one piece , can also be constructed as a connecting rod lens ( 10 ′), both as a biconvex rod lens main element with positive or negative meniscus elements cemented to both sides , and as a biconcave rod lens main element ( 10 ′) with biconvex lenses ( 12 ′, 13 ′) cemented to both sides . in addition , as an eighth embodiment illustrated in fig6 , in embodiments five and six the outer rod lenses ( 20 ″ xx , 30 ″ xx ), in addition to the lens elements ( 22 ″, 32 ″) cemented to them on the side turned inward , also have lens elements ( 23 xx , 33 xx ) cemented on their side turned outward . these lens elements ( 23 xx , 33 x ) of the outer rod lenses ( 20 ″ xx , 30 ″ xx ), turned outward , can be biconvex if the side of the outer rod lens main elements turned outward is concave , or they can be concave on the side turned inward and convex on the side turned outward , that is as meniscus elements ( 23 xx , 33 xx ), if the outer rod lens main elements ( 21 ″ xx , 31 ″ xx ) have a convex curvature on their side that is turned outward . according to the invention , the outer rod lenses ( 20 , 30 ; 20 ′, 30 ′; 20 ′ xx , 30 ′ xx ; 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ) are always constructed in such a way that they are symmetrical to one another with respect to a center plane ( 100 ) of the image transmission system that is perpendicular to the optical axis . by means of the modifications of the seventh and eighth embodiments , the image curvature can be reduced advantageously . among the aforementioned embodiments , a ninth can result from making the lens main elements of the connecting lens or lenses , if they are biconvex or biconcave , symmetrical with respect to their center plane that is perpendicular to the optical axis . the advantage of this type of symmetrical configuration consists in a production process that can more easily be unified . it is also possible , in a tenth embodiment ( as shown in fig1 , 4 , 5 , or 6 ), that the center rod lens ( 10 ′) in the previous embodiments , if it is configured as a connecting rod lens ( 10 ′), can include ends which are symmetrical with respect to a symmetry plane ( 100 ) running through the center rod lens ( 10 ′) perpendicular to the optical axis . the ends of the lens elements ( 10 ′) should advantageously be unified . in an eleventh embodiment ( as can be seen in fig1 , 2 , 3 , 4 , 5 , or 6 ) the lens elements ( 12 ′, 13 ′; 22 ′, 32 ′; 22 ′, 23 xx , 32 ′, 33 xx ; 22 ″, 12 ′, 13 ′, 32 ″; 23 xx , 12 ′, 13 ′, 33 xx ; 23 xx , 22 ″, 12 ′, 13 ′, 32 ″, 33 xx ) cemented to the main element can be symmetrical as a hole to one another , which is advantageous because of additional unification , even of all lens elements . in the aforementioned embodiments with a center connecting lens ( as can be seen in fig1 , 4 , 5 , or 6 ), according to a twelfth embodiment , this connecting lens ( 10 ′) can be configured as a cylinder as a connection between the rod lens main element ( 11 ′) and the lens elements ( 12 ′, 13 ′) cemented to it . in a thirteenth embodiment ( as in fig2 through 6 ), among the aforementioned embodiments with outer connecting rod lenses ( 20 ′, 30 ′, 20 ′ xx , 30 ′ xx ; 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ), these lenses are configures in cylindrical form ( 20 ′, 30 ′, 20 ′ xx , 30 ′ xx ; 20 ″, 30 ″; 20 xx , 30 xx ; 20 ″ xx , 30 ″ xx ). additional modifications are possible in that , instead of one lens element ( 12 ′, 13 ′; 22 ′, 32 ′; 22 ′, 23 xx , 32 ′, 33 xx ; 22 ″, 12 ′, 13 ′, 32 ″; 23 xx , 12 ′, 13 ′, 33 xx ; 23 xx , 22 ″, 12 ′, 13 ′, 32 ″, 33 xx ), a number of lens elements can be cemented onto certain ends of one or more connecting lens rod main elements . for instance , it is possible to add a thirteenth embodiment which corresponds to the first embodiment , except that in addition to the biconvex lens elements ( 12 ′, 13 ′) cemented to the lens main element ( 11 ′) of the center rod lens ( 10 ′) on the side turned outward , meniscus elements are also cemented to these biconvex lens elements on the side turned outward . the advantage here is that the image curvature can be reduced . supplementary to the illustrated and described embodiments , it is of course also possible at any time to insert optically inactive surfaces , especially plane surfaces , into the image transmission system without going beyond the framework of the invention . thus the individual lenses can be constructed from still more elements than indicated in the aforementioned embodiments . in using lenses made of still more elements , data of any additional lens elements can be adapted in known manner by means of commercially available optical design programs .