On the weekend one of the talks I gave was on composition and it was clear that there is interest in learning more so given that composition is a big issue with me, here goes:
I have talked about simplicity in design as being desirable in good images, but it might actually be better to describe it as clarity - the implication being that the important elements of the image stand out somehow so that sense can be made of them, they can be seen in relationship and elements of the image which aren't critical to its design are down played.
If an element is overlapped by 3 other things which don't need to be overlapped, the element in question is not going to be as clear as if it were to stand out against a plain background. On the other hand, if the objects it overlaps are in fact related to it and part of a sequence or series, well that's different, isn't it?
Clarity comes from the relative brightness of the element - in general if it is significantly lighter than surrounding elements it is going to be better noticed - so burning in the surround or lightening the element itself may be important.
If the pattern of elements makes your eyes look left then right, back to the left then up to the top, down to the bottom and finally back to the middle, that isn't clear. If you expect the eyes to follow a pattern, keep it a simple one and make it so there is a flow of the way you want the eye to follow rather than looking like one of those old computer games Pong.
Clarity can come from blurring the background. One of the tricks with Helicon Focus is you can get great depth of field within a complex object yet because you used a wide f stop and didn't keep shooting the sequence into the background, it remains blurred while the object itself has full depth - much more clear than simply stopping down to f22 and hoping for the best.
Clarity is very much about moving around until the main elements of the subject do fall on a simple background. As a rule, unless it is an important relationship, straight lines like power lines and tree trunks and so on should not sprout from the tips or corners of compositional elements (like girl friends heads). Nor do you usually want to divide the element in half with a background line - an unequal fraction is usually better unless you have a specific purpose. Remember that for the purposes of composition, the horizon is an object or element that must be considered. All things being equal, an element will look better if either mostly above or below the horizon and not with the horizon going right through the centre of the element.
Clarity comes from not having too many elements in the image, unless they all relate in the same way (say through shape or tone). It's so very tempting when composing a landscape for example to want to include that lovely curve on the right - that fantastic shape on the left and the terrific cross in the foreground - but all being different, it really doesn't matter how good each is, if they don't strongly tie in, one or more has to go.
Of course what often happens in real life when looking for interesting images, is that when you get tough and eliminate the great stuff that doesn't relate, you are left with a weak image - damned if you do and damned if you don't. All you can do at that point is pack the equipment away, recognize this particular setup as another 'might have been, almost was' and move on.
The more you think about things like this though, the fewer images that get you really excited on the shoot only to look like total crap when you get home - that is so discouraging to ones continued enthusiasm for photography.