Multi-purpose telescope

A multi-purpose telescope comprising a Petzval type objective having a front achromat and a rear achromat widely spaced from each other, and an iris disphragm located between said achromats and proximate to said rear achromat, and wherein said Petzval type objective includes lens elements LI and LIII made of BK-7 glass having a refractive index of 1.5168 and an Abbe number of 64.2 and lens elements LII and LIV made of SF-12 glass having a refractive index of 1.6477 and an Abbe number of 33.8 and said lens elements have the parameters specified in the following table wherein all dimensions are given in millimeters:

• ______________________________________ Lens Lens Lens Clear Ele- Thick- Separa- Aper- Outside ment Radii ness "d" tion "s" ture Diameter ______________________________________ r1=+411.43 LI d1=16.0 126 132 r2=-544.15 s1=6.0 r3=-501.7 LII d2=12.0 126 132 r4=-6890.0 s2=480.0 r5=+253.263 LIII d3=8.0 60 64 r6=-253.263 s3=0.0 r6=-253.263 LIV d4=8.0 60 64 r7=-1386.0 ______________________________________