Category Archives: a – What makes a colour

Primary and secondary colours

The requirement of this exercise is to find a scene or scenes dominated by a one of the six single colours of the primary or secondary category:-


Colour Wheel

Originally I had in mind selecting part of the high street and take colour swabs so to speak of what I saw there.  Another idea was to go in a shop and see if I could get the full range in there.  I also had the idea of seeing what options were closer to home and thought it might be interesting to do an experiment and see if I could identify, or at least get close to, the colours in the circle on a macro level.  Its interesting to note that on my, calibrated, monitor the six colours are much more distinct than the printed version.  I chose the bathroom to do this as such colour there is in there, is on a relatively small scale:-


The Bathroom


Detail of label F2.8 @ 1/60 ISO200



Detail of label F2.8 @ 1/40 ISO200 (exposed as -.7 stop)





Detail of label F2.8 @ 1/15 ISO200 (exposed as +.7 stop)

Of the three above I thought the last one is an approximation of the violet in the circle but at the time I was shooting I was using a printed version of the circle and now on examination its not as close as I thought it was!



Tube end detail F2.8 @ 1/10 ISO200



F2.8 @ 1/20 ISO200 (exposure reduced by -.7 stop)





F2.8 @ 1/6 ISO200 (exposure increased by .7 stop)

In the case of the blue I think the underexposed version is a much closer match.

For red I used a bottle cap:


Bottle cap F3.3 @1/10 ISO200



Bottle cap F3.2 @ 1/20 ISO200 underexposed at .7 stop










Bottle cap F3.2 @ 1/8 ISO200 overexposed at .7 stop.

To my eyes this time the overexposed shot comes very close to the circle colour.

The Orange I found was the interior of a wash bag.


Washbag F2.8 @ 1/13 ISO200


Washbag F2.8 @ 1/20 ISO200 underexposed at .7 stop





Washbag F2.8 @ 1/6 ISO200 overexposed at .7 stop


The yellow was a detail from the artificial flower on the windowsill


Petal edge F2.8 @ 1/200 ISO200



Petal edge F2.8 @ 1/320 ISO200 underexposed at .7 stop




Petal edge F2.8 @ 1/125 ISO200 overexposed at .7 stop








To my eyes the very edge of the petal is the closest to the yellow but, interestingly, the out of focus area on the right hand side is also a good match in this shot.

For the green I used a shampoo bottle.  This was quite reflective and because of its position in the bathroom one edge was more in shadow so there was a difference in the shade of green straight away.:-


Bottle at F2.8 @1/30 ISO200







Bottle at F2,8 @ 1/40 ISO200 underexposed by .7 stop




Bottle at F2,8 @ 1/13 ISO200 overexposed by .7 stop










Of the three shots I think the right hand shade of the overexposed shot is the closest although, as the course book indicates, there is a lot of variance in green!

I found this a useful exercise as my colour sense is not particularly strong in terms of identifying shades and is something worth developing or practising.



Controlling the strength of a colour – cameras with a manual option.

My original idea was to take a shot of the blue screen of my television but dismissed this because of the reflection in it.  The next idea I had was the post box just down the road which fulfilled the criteria of a strong definite colour:-


F5.6 @ 1/320 ISO200 (aperture priority)


F4 @ 1/320 ISO200 (manual)



F4.5 @ 1/320 ISO200 (manual)


F6.3 @ 1/320 ISO200 (manual)



F8 @ 1/320 ISO200 (manual)

Out of interest I measured the RGB scale at the top of the shape in the letter G.  In the “correctly exposed” F5.6 shot it was 184.  At F4 255; F4.5 252; F6.3 180 and F8 151.  The minor difference between F5.6 and F6.3 could be due to a change in daylight values?

In any event the red in the F4 shot is far weaker and not as striking as the F5.6 shot but, as might be expected, the F8 shot provides a much deeper, vibrant and somehow more solid red.

I thought I’d try the exercise with Green and Blue to see if there was a noticeable difference in the change of colour with the same range of exposures.  For the green I used a leaf from the garden.  It had a fairly reflective surface and its interesting to see with the underexposure at F8 the differences in the reflecting and less reflecting areas is not as obvious:-


F5.6 @ 1/3 ISO200 (aperture priority)


F4 @1/3 ISO200 (manual)



F4.5 @ 1/3 ISO200


F6.3 @ 1/3 ISO200 (manual)


F8 @ 1/3 ISO200 (manual)

Of the shots above I think, to my eyes anyway, that the F6.3 shot is probably the most accurate as the 5.6 one is a tad too light (and more reflective in terms of highlights) although it is a close run thing between this and the F8 shot.  This seems to echo the red pictures above

For the blue I used a nylon jacket :-


F5.6 @ 1/3 ISO200 (aperture mode)


F4 @ 1/3 ISO200 (manual)


F4.5 @ 1/3 ISO200 (manual)


F6.3 @1/3 ISO200 (manual)


F8 @1/3 ISO200 (manual)

I this case I think the 5.6 shot is pretty close but again its close with the 6.3 shot.

As to what can be inferred from this test (albeit a very rough one) I think there may be an argument to say that variations of exposure from the norm may be appropriate depending on the colours involved.  It is the case that there are a loot of variables involved here, the  camera takes an average meter reading , light may change, reflectivity etc.  The answer, I guess is to experiment both at the point of taking the shot (assuming time permits such experimentation) or in post production.

It also shows that my recollection of colour is not good as memory (well mine anyway) is an unreliable guide.  To combat this shortcoming I often use (although not as often as I should) this little accessory:-


X-rite color checker passport

This enables me to make accurate white balance settings (when I remember) and create colour profiles in lightroom for my cameras as well as being a handy point of reference for colour.