C. Estimating cell size You will need to do all these steps for EACH cell type you are going to examine: Cheek epithelium, Elodea, potato, red onion. Estimate the size of a SINGLE cell. Make sure you can identify a single cell in the leaf, onion, potato etc. since these cells are naturally packed together as tissues. 1. Ocular Lens Diameter of field Objective Lens Total Magnification of view 10X 10X 10X 4X 10X 40X 4 mm 1.6 mm 0.4 mm 40X 100X 400X CONVERT mm measurements to um. Remember: 1mm = 1000μm lum = 0.001 mm