Skip to Step 4 unless you specifically need to examine the sensor as any dust or fingermarks may have a major impact on image quality and correct realignment on reassembly is critical. It should therefore preferably be left alone. The image sensor and infrared filter can be inspected or replaced without further disassembly of the lens.

With a small craft knife, scrape away the locking glue from the 3 screws securing the image sensor plate to the back of the lens. Take care to remove any loose fragments of glue which might fall into the lens.

Note the initial positions of the heads of the 3 screws and remove them, counting the number of turns required for each. Remaining glue will make these stiff - take care not to burr the heads. Gently ease the image sensor away, keeping the lens face-down on the bench.

Put the sensor aside, safe from dust contamination, such as in a self-sealing polythene bag.