A spectral imaging apparatus (100, 200) for processing electromagnetic radiation, the EM radiation originating from a target scene and comprising a wide range of frequencies, the apparatus comprising: a dispersive element (2; 30) for receiving EM radiation from the target scene and promoting differing amounts of dispersion depending on the frequency of the EM radiation, a deformable lens arranged to receive EM radiation from the dispersive element, an imaging sensor for detecting EM radiation across the wide range of frequencies, and arranged to receive EM radiation from the deformable lens, wherein the deformable lens is operable to adopt any one of a plurality of focal conditions, each focal condition tending to focus a different range of the EM radiation at the imaging sensor, each focal condition thereby defining a component band for the EM radiation, and wherein the dispersive element is a selectively dispersive element, having a dispersive condition and a non-dispersive condition and being operable to switch from one condition to the other, the selectively dispersive element comprising: a First Switchable lensing device (FSLD) which in a first state allows EM radiation to pass substantially unaffected and which in a second state collimates the received EM radiation, wherein the FSLD is arranged to receive EM radiation from the target scene; and a Second Switchable Lensing Device (SSLD) which in a first state disperses received EM radiation and in a second state allows EM radiation to pass unmanipulated, the SSLD being arranged to receive light from the FSLD, wherein the FSLD and the SSLD may both be placed in their first states to effect the dispersive condition of the dispersive element, or may both be placed in their second states to effect the non-dispersive condition of the dispersive element, and wherein the SSLD comprises: a diffractive element having a first refractive index and comprising surface relief elements; and a liquid crystal element, complimentary to the diffractive element and operable in the first state of the SSLD to have a refractive index different to the first refractive index and in the second state of the SSLD to have a refractive index substantially matching the first refractive index. a dispersive element (2; 30) for receiving EM radiation from the target scene and promoting differing amounts of dispersion depending on the frequency of the EM radiation, a deformable lens arranged to receive EM radiation from the dispersive element, an imaging sensor for detecting EM radiation across the wide range of frequencies, and arranged to receive EM radiation from the deformable lens, wherein the deformable lens is operable to adopt any one of a plurality of focal conditions, each focal condition tending to focus a different range of the EM radiation at the imaging sensor, each focal condition thereby defining a component band for the EM radiation, and wherein the dispersive element is a selectively dispersive element, having a dispersive condition and a non-dispersive condition and being operable to switch from one condition to the other, the selectively dispersive element comprising: a First Switchable lensing device (FSLD) which in a first state allows EM radiation to pass substantially unaffected and which in a second state collimates the received EM radiation, wherein the FSLD is arranged to receive EM radiation from the target scene; and a Second Switchable Lensing Device (SSLD) which in a first state disperses received EM radiation and in a second state allows EM radiation to pass unmanipulated, the SSLD being arranged to receive light from the FSLD, wherein the FSLD and the SSLD may both be placed in their first states to effect the dispersive condition of the dispersive element, or may both be placed in their second states to effect the non-dispersive condition of the dispersive element, and wherein the SSLD comprises: a diffractive element having a first refractive index and comprising surface relief elements; and a liquid crystal element, complimentary to the diffractive element and operable in the first state of the SSLD to have a refractive index different to the first refractive index and in the second state of the SSLD to have a refractive index substantially matching the first refractive index. a First Switchable lensing device (FSLD) which in a first state allows EM radiation to pass substantially unaffected and which in a second state collimates the received EM radiation, wherein the FSLD is arranged to receive EM radiation from the target scene; and a Second Switchable Lensing Device (SSLD) which in a first state disperses received EM radiation and in a second state allows EM radiation to pass unmanipulated, the SSLD being arranged to receive light from the FSLD, a diffractive element having a first refractive index and comprising surface relief elements; and a liquid crystal element, complimentary to the diffractive element and operable in the first state of the SSLD to have a refractive index different to the first refractive index and in the second state of the SSLD to have a refractive index substantially matching the first refractive index.