Kit for microscopic observation comprising: - a light source; - an optical system equipped with at least one magnification lens assembly defining an optical axis (X-X); and - a frame crossable by the light generated by said light source and configured for supporting: a sample holder, a portable electronic apparatus equipped with an image acquisition device, and said optical system interposable between said sample holder and said image acquisition device; said optical system being also configured for being movable in a guided manner on said frame, so as to allow aligning said optical axis (X-X) with said image acquisition device; and - a carrying body configured for receiving in abutment said frame and housing said light source directing light towards said optical system through said frame; wherein said optical system comprises a base crossable by the light generated by said light source, which can be laid on said frame, and which is equipped with an adjusting mechanism configured for adjusting the axial distance of the lens assembly from the frame; wherein said adjusting mechanism is located in a laterally spaced position relative to said lens assembly; said kit being characterized in that said adjusting mechanism comprises a screw element passing through said base, the distal end of which is configured for abutting against said frame. - a light source; - an optical system equipped with at least one magnification lens assembly defining an optical axis (X-X); and - a frame crossable by the light generated by said light source and configured for supporting: a sample holder, a portable electronic apparatus equipped with an image acquisition device, and said optical system interposable between said sample holder and said image acquisition device; said optical system being also configured for being movable in a guided manner on said frame, so as to allow aligning said optical axis (X-X) with said image acquisition device; and a sample holder, a portable electronic apparatus equipped with an image acquisition device, and said optical system interposable between said sample holder and said image acquisition device; said optical system being also configured for being movable in a guided manner on said frame, so as to allow aligning said optical axis (X-X) with said image acquisition device; and - a carrying body configured for receiving in abutment said frame and housing said light source directing light towards said optical system through said frame; wherein said optical system comprises a base crossable by the light generated by said light source, which can be laid on said frame, and which is equipped with an adjusting mechanism configured for adjusting the axial distance of the lens assembly from the frame; wherein said adjusting mechanism is located in a laterally spaced position relative to said lens assembly; said kit being characterized in that said adjusting mechanism comprises a screw element passing through said base, the distal end of which is configured for abutting against said frame. wherein said optical system comprises a base crossable by the light generated by said light source, which can be laid on said frame, and which is equipped with an adjusting mechanism configured for adjusting the axial distance of the lens assembly from the frame; wherein said adjusting mechanism is located in a laterally spaced position relative to said lens assembly; said kit being characterized in that said adjusting mechanism comprises a screw element passing through said base, the distal end of which is configured for abutting against said frame.