I love the wonderful detail you can capture in a macro shot, and my Tamron 90 mm f2.8 lens does a fine job of sharpening up details when I really get close to my subject. But I re-learned (or re-demonstrated to myself) the other day, how important it is to get the settings right before shooting, especially if the subject is bigger than a small bee.
Here’s a quick demonstration of the effect of aperture opening on the depth of field, using the same lily. I stood in the same spot, focused on the same spot on the flower (the stamens), and just changed the aperture from wide open (f2.8) to very small opening (f16). You should see an increase in the depth of field and fine focus in the series going from the first photo to the last. Click on any of the photos to see the resolution and detail in the anthers — it is far sharper at f16 than any of the other apertures.
There is a trade-off to getting better depth of field in the subject, however, because I have also sharpened up (unintentionally) the background, which was nicely blurred and complementary to the flower at f2.8 and is now competing for attention with the lily at f16. So, I guess the lesson here is to either choose a better background for the whole flower shot, settle for less than perfectly sharp (e.g, at f 5.6) or shoot less than a whole flower (like the very first photo). Or….use a different lens!