I was about to go search for portraits I took with several different macro lenses to illustrate a point, but I stopped and thought for a moment ...
Not about sharpness and not about whether a particular piece of equipment is 'right' or 'wrong' ... at least not without considering several factors ... like the subject's age and skin condition, location and lighting conditions etc, and most important: what I need in the photo.
When I see discussion about whether a lense is 'sharp' enough for this or that application, or when considering which lense to choose for a task, I sometimes ask myself the above, and somewhere at the back of my head, I also bear in mind the type of post processing (post) that's going to be done to the work as well as the sensors used.
Then my mind gets hauled back to long ago lessons on what makes a lens 'sharp', or not so sharp, and remember that resolution, often measured in terms like lines per inch or nowadays, pixels per inch (not the common, inaccurately used Dots per inch), is not the be all and end all to benchmark the performance of a lense.
Without getting technical, resolution is only one component that defines the perception of how 'sharp' a lens can be under certain conditions.
The others include things like contrast, accutance, distortions, abberations and so on. ALL of these contribute or detract from the perceived performance of a lens, again, and I stress, under a given set of shooting conditions.
Why the emphasis?
Simple.
Assuming we all know about stuff like contrast, and how it affects the definition of objects and edges, just like accutance, we know that the same exact lense can be made to seem more or less sharp, to some extent, simply by altering conditions.
Similarly, when the envelope of say, lens coatings are pushed to the limits, you might get things like flare and CA, all of which negatively (relative term) affects how an image is recorded.
When you consider all the parts that makes up the final picture, you'll realise that choices aren't made simply on "Oh, we need a super sharp photo - just use a macro lens." If life were that simple, you would likely see macro lenses on almost every portrait, flashion and glamour photographer's camera. That, is likely to be not the case. But WHY?
Look around at what working portrait professionals are using, and what lenses they use. Don't limit yourself, search on youtube and many of the US and European sites where a lot of glamour and fashion is showcased. If possible, look out for sites where working professionals contribute.
Take it one step further and consider another sector: the commercial photographer specialising in product and industrial photography. Take note of what lenses they are using.
Be generous.
Note down a sampling (fairly) of say 100 photographers and consider the results you find, but more importantly, examine the CONDITIONS under which they shoot. It might give hints at their equipment choices. Remember, these guys do not shoot for fun. They have businesses, reputations and families to support, and sometimes, astronomically lavish lifestyles as well. Naturally, one would assume that as far as possible, they would choose THE BEST lenses for the job.
I know it's not the most accurate analogy, (or maybe even the most useful) but there's nothing wrong in using a surgical scaple to cut a steak. Why don't we use them in place of the knives that we do?
Having said that, there is another arguement that could rationalise the use of macro lenses for portraits - to compensate for less than ideal conditions and post work.
It would be great to hear more thoughts.
