Just to share with you all some of the macro shots taken with the various extension tubes setup. All these were taken with the 85mm f1.8 at Av mode set at f1.8, handheld.
No need to comment why it was not taken at f11 above for macro cos din bother to use tripod or flash. Just to share the magnification you can expect from these various setups and the DOF at Ap of f1.8
85mm with no tubes
With the 20mm tube
With the 36mm tube