Here are three where color is a main element, from the hues of the plant kingdom to the golden glow of sunrise. The <span style="text-decoration: line-through;"]firstsecond will be my entry, based on initial polls...(and thanks, all!)
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EOS 5D Mark II, MP-E 65mm f/2.8 1-5x Macro @ 4x, 1/60 s, f/11, ISO 400, MT-24EX
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EOS 5D Mark II, MP-E 65mm f/2.8 1-5x Macro @ 5x, 1/60 s, f/11, ISO 400, MT-24EX
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EOS 5D Mark II, TS-E 24mm f/3.5<span style="color: #ff0000;"]L II, 1/15 s, f/10, ISO 100, +6 shift