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The RX100 is an interesting camera when it comes to using diopters
I have inon diopters and I found that the camera would focus only at a specific focus distance regardless of zoom so once you work that out (it is somewhere close to the declared 165mm) you can zoom in to the max
To work out the distance you can use manual focus and peaking
You should be able then to zoom to 3.7 with one or two diopters
Obviously the focus distance will be shorter with two and give more magnification