The ornamental design for a guidinginstrument for telescopes, as shown and described.
FIG. 1 is a right side perspective view of a guiding instrument For telescopes in accordance with the new design;
FIG. 2 is a right side elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a front elevation view thereof; and,
FIG. 7 is a rear elevation view thereof.
The broken line separation and bracket are used to indicate that, for ease of illustration, no particular length is claimed. The broken lines shown in FIG. 7 represent the bounds of the claimed design; the broken lines form no part of the claimed design.