We like our decisions to have sensible explanations. It is why people buy an unnecessarily powerful car and talk enthusiastically about its safety features, or spend a small fortune on a watch because apparently knowing the time has become unusually complicated. Boudoir photography has its own versions: “It’s a wedding present”, “I’m turning 40”, or “My partner would love it.”

All are perfectly legitimate reasons, but sometimes I suspect they also perform another useful function. They give us permission to do something we already wanted to do. A bridal boudoir shoot is a wonderful example because a woman may arrive absolutely certain that she is creating a gift for her partner, then we start photographing, she sees what we are creating, and suddenly there is considerably more discussion about which photographs she likes.

The gift hasn’t stopped being for him. It has simply acquired a second owner. Your partner may eventually receive an album, but you had the experience of creating it, and those are two quite different gifts.

If feeling sexy were simply a matter of putting on expensive lingerie, the industry would have solved the problem years ago. Buy bra, add stockings, apply lipstick and have the entire sensual crisis resolved by lunchtime. Human beings are annoyingly more complicated.

When somebody tells me she wants to feel sexy again, she is often talking about something broader. She may be talking about being looked at differently, but quite often she is talking about looking at herself differently. We become extraordinarily accustomed to our own reflection, complete with the bits we like, the bits we have decided not to like and the angle we automatically adopt when somebody produces a phone.

I don’t believe a photoshoot magically rewires somebody’s relationship with herself, and I am suspicious of photography being sold as therapy with better lighting. What photography can do is interrupt the familiar. Light, posture, expression and perspective can show you the same person you see every morning, but in a way you weren’t expecting to see her.

Sometimes that is enough to make a few long held opinions about yourself look rather less convincing.

Not every woman who contacts me wants the same kind of photographs. Some want beautiful, elegant boudoir, some are curious about fine art nude photography, while others want something darker, more provocative or unmistakably erotic. Quite a few don’t know exactly what they want until we start.

I think we sometimes create an unnecessary hierarchy around these things, as though lingerie photography is sophisticated, nudity is brave and erotic photography requires a small committee to approve it. It doesn’t. Wanting to explore your sensuality or sexuality in photographs is a perfectly legitimate reason to book a shoot, whether that means beautiful lingerie, complete nudity or something considerably more adventurous.

Sometimes the motivation is nothing more complicated than curiosity: “I’ve always wondered what I would look like photographed like that.” I rather like that reason because it doesn’t require a manifesto. You don’t receive additional points for taking your clothes off, and there is no disappointing bronze medal if you keep them on. The photographs only need to go as far as you want them to.

Most of us spend an impressive amount of time maintaining a reasonably consistent character. There is work you, parent you, partner you and Saturday morning supermarket you. These versions need to be dependable. Nobody particularly wants their accountant to announce halfway through a tax return that she is experimenting with a mysterious new persona.

A photoshoot gives you temporary permission to be less consistent. You can be glamorous if you are normally practical, provocative if nobody would ever use that word to describe you at the office, or finally wear the thing you bought three years ago but have never found an occasion for. You can be elegant, sensual, nude, erotic, playful or several of those things before lunch.

The interesting part is that none of this necessarily involves pretending to be somebody else. They may simply be parts of you that don’t get much diary space.

Birthdays bring a lot of women into the studio. Thirty, forty, fifty and sixty seem to have extraordinary psychological power considering round numbers are largely an accident of our having ten fingers. They make us stop for a moment and take stock, which can be a wonderful reason to create photographs of yourself at a particular point in your life.

What I dislike is the quieter thought that sometimes accompanies the decision: “I should do it now while I still can.” Still can what, exactly? Be photographed? Be sensual? Take your clothes off without the authorities intervening?

I’ve photographed women across a very broad range of ages, and sensuality appears remarkably unwilling to obey the timetable we have assigned to it. Bodies change, of course they do, but so do faces, priorities and our tolerance for uncomfortable shoes. Becoming older doesn’t automatically make somebody less interesting to photograph and, quite often, experience and a reduced interest in what everybody else thinks can make the photographs considerably more interesting.

By all means use the birthday as the reason. Just don’t treat it as an expiry date.

I have photographed women after relationships ended, and there are profound ways of explaining why somebody might choose that moment for a boudoir shoot. Reclamation, renewal and rediscovering identity can all be true. There is also another possibility: sometimes, after a relationship ends, it is simply rather satisfying to look spectacular.

I don’t think we need to pretend human motivation is always noble. It rarely is. We can be sad, relieved, angry, excited and slightly vindictive before breakfast, sometimes simultaneously. A photoshoot doesn’t have to become revenge photography, and your ex certainly doesn’t need to see the results.

In fact, there can be something rather better about creating photographs that have absolutely nothing to do with them. The relationship ended. You didn’t. That seems a perfectly adequate reason to me.

Adult life is terribly fond of usefulness. We spend money maintaining houses, cars, careers and children, then purchase increasingly expensive devices that promise to make us more productive so that we can apparently spend the saved time answering more emails. Almost everything requires a justification.

A boudoir photoshoot is magnificently bad at being useful. It won’t improve your credit rating, make the WiFi faster or increase the resale value of your house. SARS is unlikely to accept your album as a deductible business expense, although I admire anyone prepared to attempt the argument.

You do it because you want to, and there is something wonderfully indulgent about that. Perhaps this is also why privacy matters so much. The photographs don’t have to become content, you don’t have to post them or collect approval from strangers, and they can remain completely private.

In a world where we increasingly photograph things in order to prove to other people that they happened, there is something rather luxurious about creating photographs nobody else is entitled to see.

Almost everybody arrives with something they are worried about. Stomach, arms, thighs, bum, scars, stretch marks or some other part of themselves they have examined far more critically than anybody else ever will. I listen because those concerns are real, and knowing about them helps me understand how somebody wants to be photographed.

What I have noticed over the years is that when clients respond strongly to their photographs, they are rarely talking about the centimetres they were worried about beforehand. They talk about an expression, their eyes, the way the light falls, or a photograph in which they look unexpectedly elegant, sensual, strong or wonderfully wicked.

The thing that occupied 80 per cent of their anxiety before the shoot can end up occupying remarkably little of their attention afterwards. That doesn’t mean the insecurity was imaginary. It simply means it wasn’t the whole picture, quite literally.

Boudoir photography has accumulated a formidable amount of serious language over the years: empowerment, healing, transformation, reclamation, self love. Some of those words describe genuine experiences, and for some clients a photoshoot does mark something deeply personal. But must we have a breakthrough every time somebody puts on stockings?

Sometimes a woman books because the photographs look fantastic and she thinks the experience might be fun. I consider this an entirely adequate motivation. You don’t need to have survived something, achieved something, lost something, reinvented yourself or reached a birthday ending in zero.

You are allowed to want sexy photographs because you would like some sexy photographs. We seem strangely reluctant to accept pleasure and curiosity as sufficient reasons for doing things, even though some of the things we value most have very little rational justification.

Perhaps that is precisely why we value them.

After more than 15 years behind the camera, I don’t think there is one answer, and that is probably what makes the question interesting. A woman can book for her partner and discover that the photographs matter just as much to her. She can book because she wants to feel sexy again and discover that feeling wasn’t quite as far away as she imagined. She can arrive planning elegant lingerie photographs and become curious about nude or erotic photography once she feels comfortable.

Or she can arrive with no grand explanation whatsoever. The reason somebody gives me at the beginning of a shoot isn’t a contract, and it doesn’t have to become the meaning of the photographs. It is simply where we start.

Perhaps that is what I have learned from asking the question for all these years: the reason gets you through the door, but it doesn’t necessarily tell us where the photographs will take you.