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 (H), a portable electronic apparatus (S) equipped with an image acquisition device (C), and said optical system interposable between said sample holder (H) and said image acquisition device (C); 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 (C); 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 (H), a portable electronic apparatus (S) equipped with an image acquisition device (C), and said optical system interposable between said sample holder (H) and said image acquisition device (C); 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 (C); and a sample holder (H), a portable electronic apparatus (S) equipped with an image acquisition device (C), and said optical system interposable between said sample holder (H) and said image acquisition device (C); 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 (C); 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 . <EOS>