I normally shoot with an 18-55mm lens on my Canon Rebel XS. It allows me to get up-close and personal with my subjects, but still back out far enough to shoot landscapes. In most instances, particularly tight shots, I shoot with aperture priority between f/5.0 and f/6.5. This produces a depth-of-field that allows individual plant parts to be in focus, while blurring the background. To my eye, this is the most pleasing way to show plant details without background distractions.
I've used this type of lens for more than six years now, so it's become almost second nature to change settings when necessary. This weekend, however, I borrowed a 50mm macro lens from a colleague. This is a lens that supports a lower minimum f-stop (2.8), and a magnification ration of 1:2.5. What this lens offers -- in common terms -- is that I can get closer to my subjects and fill the frame with smaller physical specimens. It theoretically allows me to produce more detailed images than my normal lens at the same focal distance.
When we had a brief break in the overcast, I took the 50mm macro out into the garden this morning for a trial run.
|Cercis canadensis (Eastern Redbud) (bark)|
|Fothergilla 'Mt. Airy' (seed head)|
|Hydrangea paniculata 'Little Lamb' (vegetative bud)|
|Hydrangea paniculata 'Little Lamb' (dried flower head)|
|Forsythia 'Sunrise' (flower bud clusters)|
I'm relatively pleased with the results, although I deleted about 90% of the photos I shot (compared to my usual 60-70% deletion rate). Shooting with the macro was more difficult, because the depth-of field is very shallow at f-stops lower than 4.0; the simplest hand movement slipped my subject out of focus. I often felt like I had sea legs while trying to steady myself for a shot.
But this shallow depth-of-field also gives the images an artistic quality that I can't produce with my normal lens. There is a much more subtle transition between focal plane and background with the macro lens, creating a photo you'd more likely hang on your wall than publish in a botany textbook.
After using the 50mm macro lens for a few shoots now, I can see it being a useful accessory lens, but not my primary shooting lens. Ideally, I'd carry a second camera body with a macro lens so I could switch back and forth easily between my everyday lens and the macro, using each lens when appropriate.