I get asked this question a lot: can I use my macro lens for portraits? The answer, of course, is yes. It’s a mistake to pigeon-hole lenses, or to lean too heavily on the idea that one kind of photo can only be made by one kind of lens.
So what is the issue here? A “classic portrait” lens is generally one of a medium telephoto focal length… 75mm-ish to 180mm-ish, such that we can photograph people at comfortable distances and still fill the frame with their bodies and faces. These lenses are usually thought of as have large maximum apertures.
Many portrait lenses have been venerated for decades as great for this… in 35mm film photography, for example, the 100mm-105mm focal length range was considered the “sweet spot.” I had three 105mm Nikkor lenses, two f/2.5s and an f/1.8. When digital came along and preserved the format size (a sensor size somewhere near the size of a 35mm film frame), those focal lengths translate well.
Okay, Richard. I have a 100mm macro lens. It’s in that focal length range. Is it a good portrait lens? There are a couple of factors that might impair a macro lens’ ability to make great portraits.
1. They are optimized to be their sharpest a very close focus settings. One consequence of this is “hunting,” in which autofocus moves forward and back trying to find the focus, and macro lenses have a huge range in which to hunt.
2. They often included less-than-idea “bokeh,” a term which describes the out of focus area of an image. For example, one of my favorite macro lenses, the AF Nikkor 60mm f/2.8, is amazingly sharp, but exhibits ratty, seven-sided bokeh. It is not a good portrait lens in most instances.
A zoom in this focal length range can have some of the same drawbacks: they are good at all focal lengths, but aren’t spectacular at any of them. Zoom are also heavy, and can attract a lot of attention and be a little intimidating. An exception to this might be the big f/2.8 zooms, which are very popular among portrait shooters, but also very expensive and very heavy.
My favorite portrait lens is my AF-S Nikkor 85mm f/1.8G, which is sharp, lightweight, affordable, and exhibits beautiful, smooth bokeh. I can make backgrounds vanish into the ether by shooting with it at f/2.0 or so.
Before you get out the credit card and start buying lenses, consider also that any and every camera and lens can make great portraits in the right circumstances. If you have a macro lens, make some portraits with it. It might be the lens for you.