Of course, the question may be overly broad, since the field of photography has so many different facets that rely on different, or even exclusive, traits. I will never be more than a mediocre still life photographer, for example, because I lack the necessary trait of patience. The idea of taking three days to set up a single shot makes me slightly queasy, but I still appreciate the anal, painstaking attention to detail of photographers like James Wojcik.
And, of course, there's a bit of muddle over what makes someone a good photographer versus a good professional photographer. There are lots of people with fantastic portfolios who don't have the traits necessary to handle assignments well, and the art world is almost defined by people who make great work but have no idea how to market it.
Over the years, I've gotten to know a lot of great photographers -- not just the people with great work on Flickr, but those who have really succeeded in getting their work out there, from major grant-winners to photographers who regularly shoot for the New York Times, Forbes, Time, the cover of Vogue, etc. Again, this is just a small sub-set of the professional market, but it's interested me that these people have a lot of overlapping traits -- you can almost tell they're great photographers just by talking to them, and certainly by watching them work, even without seeing the prints. So, here are a few ideas based on my experience, but I'd like to hear more about traits that have helped you, traits you wish to develop, or traits that are essential to particular branches of photography.
DRIVE: This is a vague term, and is probably key to success in virtually any field, but it seems particularly true to the field of photography, which constantly requires you to get out of bed and make something new and exciting. Philosopher Charles Saunders "Chucky" Peirce defined doubt as an itch of the mind that drives someone into inquiry; I see drive as similar -- an itch that makes you vaguely uneasy if you're not pressing forward and creating. It's that itch, that feeling that you really wouldn't rather be doing anything else, that gets people through obstacles and frustrations. Thank about war photographers, who take this to an extreme. An old WWII saying about these guys was "The brave ones were shooting the enemy. The crazy ones were shooting film." Strongly related is …
COMPETITIVENESS: Let's face it … photography is a crowded field. Millions of people are taking photos each day … what's going to make yours worth looking at? In the end, successful photographers I know take the work of others as an inspiration, always trying to go one step beyond. Someone like Phil Toledano can look at fashion photography, see it as mostly vapid, and try to inject some fun.
CREATIVITY: Duh. All you have to offer, in the end, is your vision. It has to be compelling.
CHARM: (People photography). It's no surprise that a photographer who works with people has an advantage if they have good people skills. When people think of photographers, these are often the traits that first come to mind -- that slightly sleazy but charming fashion photographer archetype. From documentarians to portrait photographers, the most successful ones I know tend to ooze a charisma that puts people around them at ease. Developing this can be a huge challenge for beginning photographers, harder than learning how to make a good exposure. Sometimes this charm is expressed in unconventional ways: When Avedon got the dog-loving Duke and Dutchess of Windsor to express emotion by telling them his taxi had run over a dog on the way to the shoot, he was using his considerable people skills.
PATIENCE: (particularly landscape, wildlife, and still life). Waiting four hours for a lion to yawn. Spending a day at a location just examining the quality of light at different times of the day. Setting up 18 different strobes to light a radish. Some forms of photography require an endless ability to focus on a single task. What's that like? Related is anal-retentiveness: Even in the days before photographers were their own Photoshoppers, many of the best photographers were also extremely skilled printers, and had thousands of darkroom techniques to bring out the most of their photographs. Ansel Adams is only the most famous of these.