In this exercise, I created a still life using sweets, modelling clay and drinking straws laid on my grey card that I use for manually setting the white balance. The object of this exercise is to use colour filters when converting a colour image to black and white to improve the tone and contrast of the black and white picture. This can be achieved with digital photography by using the colour filter options in Photoshop or Lightroom by adding or subtracting the colour values on the control sliders found in the greyscales functions, available to both of these programs. These features simulates in a more controllable way the adding of a coloured filter to the end of a lens on a camera when photographing with black and white film.
I began this exercise by using my grey card to set the white balance for my camera, I then I set up my still-life with the camera set on a tripod positioned over the subject. I used my 105mm lens, manually focused and set to aperture priority, ISO 100 and I used a cable remote to trip the camera.
First image remains as shot in colour.
Second altered in Photoshop with the greyscale function with no filter adjustments.
Third, fourth, fifth and sixth images all adjusted in Photoshop with one filter raised to simulate a coloured filter over the lens but with the other primary colour sliders lowered to adjust tone and contrast.

Apart from sharpening this image has been untouched and simply converted to JPEG.
Original.
Photoshop – Filters – Camera Raw filter – HSL/Greyscale – tick box “Convert to Greyscale”.

This image has been simply converted to the grey scale in Photoshop without any adjustments to the colour filter sliders which were set to the following default settings:
RED – +7, Orange – +2, Yellow – 0, Greens – -13, Aquas – -22 Blues – +5, Purples – +5,
Magentas – +7.
Red filter.

Filter sliders:
RED – +100, Orange – -27, Yellow – -36, Greens – -41, Aquas – -22 Blues – -69, Purples – +5,
Magentas – +7.
Yellow filter.

Filter sliders:
RED – -42, Orange – -8, Yellow – +11, Greens – -19, Aquas – -22 Blues – -23, Purples – +5,
Magentas – +7.

Filter sliders:
RED – -49, Orange – -21, Yellow – -33, Greens – +78, Aquas – -22 Blues – -13, Purples – +5,
Magentas – +7.

Filter sliders:
RED – -12, Orange – -29, Yellow – -33, Greens – -77, Aquas – -22 Blues – +100, Purples – +5,
Magentas – +7.
By playing with these colour filters in the grey scale I have been able to alter the appearance of all the items on the grey background. However, the grey background itself, has remained constant in all the images.