The invention relates to a charged-particle apparatus having a charged particle source with an optical axis; a magnetic immersion lens comprising a first lens pole and a configurable magnetic circuit; and a first sample stage movable with respect to the optical axis. The apparatus has a first configuration to position the sample, mounted on the first stage, with respect to the optical axis and a second configuration, having a second lens pole mounted on the first stage and intersecting the optical axis, equipped with a second sample stage to position the sample between the two lens poles and is movable with respect to the optical axis, causing the optical properties of the magnetic immersion lens to differ in the two configurations, and can, in the second configuration, be changed by positioning the second lens pole using the first stage, thus changing the magnetic circuit.