As the text for the assignment states there are not many true diagonal lines, mostly they are the effect of perspective or rather point of view.
Image 1 – Chess Set
As you can see from the image above this chess set is perfectly square. Yet when taken at a low angle, up very close with a 20mm lens all help to accentuate the convergence of perspective. But to be clear it is the viewpoint that alters perspective and not the lens.
Image 2 – taken at the Brighton council offices, the angle of the shot has created heavy diagonals in the image plus the pergola and its shadow have created long converging tramlines.
Image 3- with a very low view point and a wide angle lens, again my ever useful 20mm, my front door has developed some rapidly converging diagonal lines..very Alice in Wonderland.
Image 4 – looking down at a 30 degree angle from the Sky Deck at the top of Eureka Tower.
This last image could also be used for triangles…
A few of the shots that did not make my final 4 :