Film users generally wanted the grain to be conspicuous for effect (grainy high contrast) as found in ISO 1600 stock or non existent (nearly) as in ISO 50, Ilford PanF etc. Due to the onset of digital capture the diversity of film stock has diminished and the choices of 15 years ago are no longer available.
The notes call for the demonstration of overt graininess in the image, using the texture of the grain to enhance the image. The grain being particularly evident from small formats such as 35mm when enlarged beyond 20"x16" prints. The use of texture and the grain can be achieved using film and scanning or delivered by totally digital capture. Using digital alone there are two methods. Firstly to up the ISO at time of capture. This will increase the digital noise and simulate grain especially when converted to monochrome. The effect is less than satisfactory when used with colour as there is a tendency for the noise to shift the colour. The second method with more control is the application of grain within the post processing. CS5 has tools for this (Filter > Artistic > Film Grain) or one of the PS plug ins (Alien Skin Exposure or Nik Software Silver Efex Pro).
I no longer have a small format film camera to demonstrate grain and for for this exercise I am showing my preferred method of achieving this effect using Adobe CS5 and Silver Efex Pro.
An image taken at ISO 400 with a long lens (850mm) that has not worked too well in its current guise as a colour image. The late evening light is a difficult yellow and the prospects for the image are minimal.
Stage 1 - The Sky
Stage 1. Open in CS5 with SEP plug in and apply a Kodak P3200 TMax film for the sky and apply a blue filter to increase the contrast of the grain within the sky. I do not want the high contrast over the entire image. SEP is applied to a layer. Alt + Add Layer Mask Icon adds a black mask (the monochrome conversion will disappear) and using a soft brush with the white colour paint back in the area of the sky where the high contrast grain is required. Flatten Layers.
Stage 2 - 1st ConversionStage 2. As Stage 1 without the Blue Filter. The Mask is now only applied to the ground below the skyline. Paint in the foreground conversion. Flatten Layers.
Stage 3 - Lighten Mid Tones
Stage 3. Improve Tonal Range. Control + J to create a layer. Make a curves adjustment that lightens only the mid distance tones (small adjustment). Create a layer mask Alt + Add layer mask icon and with white brush set to 50% opacity lighten the mid greys. If over applied change to black brush and undo.
Stage 3A - Re cropped
Stage 3A. Remove the light strip at the bottom of the image with cropping.
Stage 4 - Add Contrast
Stage 4 - Add Contrast to the sky with an S Curve inside lasso area with 100px feather. Small amounts of Dodge and Burn to complete.