Translational controls Specimen up 4x Specimen down YES NO! Start with lowest power Specimen side UP Forward/back Left / right Mounting a Specimen

Adjusting the Oculars Twist eyepiece to focus Eye separation Adjusted for a single image Wide open  Double image  Closed

The Condenser Top view of condenser with selector turret Condenser aperture – 3 positions Fully stopped down Optimized for contrast & resolution Wide open

Find the Target at Low Power Low contrast image Aperture stopped down If you cannot find the target, start by focusing on an artifact in the focal plane of the specimen. A: air bubble ABC B: coverslip edge C: scratch on slide surface

Strategy for increasing Magnification Move slide up to move image down. Move slide right to move image left. Make sure the area you want to magnify is in the centre of field

Looking “Through” a Specimen Top of cell in focus Focusing through a Spirogyra filament (400x) Keep raising stage to focus through to the bottom Bottom of cell in focus

Practical – onion cells Take a segment of onion Take a segment of onion CAREFULLY peel off a section of the thin membrane CAREFULLY peel off a section of the thin membrane CAREFULLY spread it out flat on a slide CAREFULLY spread it out flat on a slide Add a few drops of stain Add a few drops of stain Place the coverslip at one side so the stain runs along the edge Place the coverslip at one side so the stain runs along the edge Carefully lower the cover slip Carefully lower the cover slip Draw a few cells (remember the rules for scientific drawings!!) Draw a few cells (remember the rules for scientific drawings!!)

Practical – cheek cells Scrape a few cells from inside your cheek, using a tongue depressor Scrape a few cells from inside your cheek, using a tongue depressor CAREFULLY scrape the cells off onto a slide CAREFULLY scrape the cells off onto a slide Add a few drops of stain Add a few drops of stain Place the coverslip at one side so the stain runs along the edge Place the coverslip at one side so the stain runs along the edge Carefully lower the cover slip Carefully lower the cover slip Draw a few cells (remember the rules…….) Draw a few cells (remember the rules…….)