Colours into Tones in Black & White

For this exercise I have to photograph a still life group of objects that include the colours red, yellow, blue and green. There should also be an grey card / grey element to the subject. 

The resulting image will then be converted to mono, with versions created using the mono filters of red, yellow, green and blue (I have also added orange to this list).

As mentioned in the introduction blog for the start of Part 3, most of the family photographs from my infancy are in black and white. By the time I became interested in taking photographs colour film was relatively cheap, so I didn't really use monochrome, but went straight into the use of colour film. 

Since I started using digital cameras, I have experimented a little with monochrome conversions, more so in the last couple of years. I now sometimes take images with a black and white conversion in mind, but don't yet have enough experience to visualise the tonal range and contrast of the final print - I take the shot then play about with the image in Aperture of Photoshop, until I think it looks right. 

I hope that this exercise will assist me in better understanding monochrome conversions and black & white photography.

I found the following scene of coloured place-mats in a trendy kitchenware shop in Islington. I Initially took the image as I recognised most of the colour wheel hues were present. The purpose built grey-card is a bonus!

D300s 20mm ISO320 f5.6 1/10th

The original image, no alteration to the colours.

(I wish I'd moved the dark green place mat onto the stack of light green & from under the grey ones. Not technically the best executed shot - the shutter speed is very low.)

  

Mono Conversion

A straight mono conversion using Aperture 2's 'Monochrome Mixer' presets. The image is now completely de-saturated, but the relative brightness of the tones of grey remain the same as as the coloured image.

Red filter added

The red filter has now been added. The red mats are now pale grey, almost white; where as the blue mats now appear black. Orange is blue's true complimentary, but the red is sufficiently close to orange in the colour circle to have a strong effect on the blues. The green mats (red's complimentary) were quite pale in colour so have not been altered to a great extent. Of note is the slither of dark green mat under the grey ones - this is now black.

Yellow filter added

The yellow filter has a less dramatic effect. The 'yellow' mats alter only slightly in brightness, as they were already almost white in the mono conversion. The violet mats they sit on have darkened only slightly, the blue mats have darkened slightly from the monochrome image. 

Green filter added

Red is green's complimentary colour - so adding a green filter deepens the reds to almost black, the violet, being close to red on the colour wheel is also deepened.

Blue filter added

The blue filter has a dramatic effect.  The blues are lightened, as is the violet. The Yellows are rendered nearly black and the (over light) green is also dakened. The red is also darkened notably, being found further away from blue in the colour wheel. Orange as a true colour is missing from the original, but the pale brown floorboards are sufficiently close to orange to be darkened considerably by the blue filter.

Orange filter added

The orange filter darkens the blues, although not as dramatically as the red filter did.

Ross Hoddinott (2007, p108) explains that the coloured filters placed over lenses (and mimicked by computer software) absorb the wavelengths of colour different to their own hue, this has the effect of enhancing tonal contrast. The images converted demonstrate this effect. For each of the images that were subject of a coloured filter, the grey mats remained relatively unchanged - there was a slight effect on this, but this was due to their slightly blue hue. The grey remains the same brightness due to its neutral colour and closeness to mid-tone grey.

The practical uses of the filters in black and white photography are that yellow or orange filters deepen the blue of skies, but lighten foliage and skin tones, adding greater tonal contrast to an image.

Conclusion

The technical reasons for the change in tones when the filters are used (covered above) seems pretty straight forward. Being able to visualise these possible alterations at point of capture may take a bit of practice, I suppose this was even the case using filters on film cameras - the visual effect of the filter on the eye when taking the photograph would still have to be interpreted and mentally converted to black and white. 

I'm now itching to play with a few mono conversions...

D300s 200mm ISO200 f4 1/160th Mono Conversion with yellow filter