Using Levels in Photoshop

Open one of your images in Photoshop. label it "Levels".

Desaturate it using Adjustment Layers.

Use the "Levels" Adjustment Layers to create 3 variations of contrast.

Here is my original color image

Here is the Desaturated (BW) Image

Here is the image adjusted for levels. 
Shadows 21, Midtones .91, highlights 231

Levesls adjusted toward the shadows
Shadows 156, Midtones .81, Highlights 171

Levels adjusted towards highlights
shadows 15, Midtones .16, Highlights 65