Ok. The Light is perfect, there’s a Photographer, and a Subject worthy of capture. All of these things are, I believe, necessary to the creation of a photograph, but there are two other things that we need to have at hand to make the photograph a reality: a lens and a camera.
The lens and the camera serve a vital function: the lens gathers light and projects it; the camera (through a variety of more or less technically sophisticated means) captures the light and converts it to an image.
Both the lens and the camera can vary widely, from the most rudimentary pinhole design (a piece of heavy aluminum with a tiny hole poked in, attached to a coffee can with a sheet of photographic paper inside, say), to the flashiest Leica or Nikon or Canon with the fanciest lens attached, and everything in between. It doesn’t really matter what sort of lens you use, and what sort of camera it’s attached to as they all function in essentially the same manner: the lens gathers light, and the camera captures this light and converts it to an image for later viewing.
If you listen to photography related podcasts for 4-7 hours per day like I do, or if you’ve come across CJ Chilvers and the ‘a lesser photographer’ blog, you’ve likely heard that the most important thing is to go out and shoot, to create, and the gear doesn’t matter. While this is true, as far as it goes, the photo podcasters tend toward the Canon 1DX or Nikon 3DX or Leica M9 and the most expensive and/or highest quality lenses they can find. If the camera and lens don’t really matter, why do the pros use kits worth $10,000 or more?
Well, first, no one ever really says that lenses don’t matter. Granted, a pinhole in a sheet of tin is fairly rudimentary, but lenses with apertures and the ability to focus on specific parts of a scene offer a considerable creative advantage over the pinhole design. Plastic lenses, as found in, say, a Holga medium format film camera will require different sorts of lighting conditions and produce different results than the $11,000 Leica 50mm f/0.95 Noctilux-M. And a Leica 50mm f/0.95 with a big, deep gouge in the front lens element will produce different (and likely less desireable) results than a $120 nifty fifty.
The lens serves a multitude of purposes related to gathering light. It determines the angle of view, the depth of field, and contributes greatly to color rendition an contrast. A 50mm lens gives roughly the same angle of view as human perception, and a f/1.4 lens will capture more light (and afford a shallower depth of field) than a lens with an aperture of f/2.8. Lenses come in a variety of focal lengths, generally ranging from 10 or 12mm on the wide-angle end, to as much as 1200mm on the telephoto end (though 300 or 400mm is far mor common, and attainable), and people regularly attach cameras to telescopes to capture images from ever greater distances. And while camera designs and capabilities change constantly, lenses tend to be designed to last for many years, and optical designs (the arrangement and shape of glass elements inside the lens) tends to remain relatively static.
This is all to say that professional photographers are likely to use (and tend to recommend) lenses with lower aperture ratings (meaning they let in more light), and the lower the f number, the more expensive the lens.
Second, it’s mostly true that the camera doesn’t matter much, but where it does matter, it matters greatly. The camera contains the shutter and the image-capturing mechanism (film or digital sensor), and in the digital era controls how sensitive the sensor is to light, the white balance, and all manner of other things that go into capturing a scene. A $30 Holga is fully capable of capturing beautiful and well-exposed images, albeit with some light-leakage and other limitations due to its construction. A $200 point-and-shoot will capture images as beautiful and useful as a $8000 professional camera, but with some limits on manual control over exposure, maximum possible print size, and low light performance. And this is why professionals, for the most part, use $8000 cameras.
There are some exceptions (CJ Chilvers, for example), and loads of well-known photographers use the camera in their iPhones as much or more than their pro bodies, though they do most of their professional work with the professional gear.
This is all to say that the lens and the camera do matter to photography. On one hand, they are both completely necessary for the creation of a photograph; on the other, the higher the quality (and the more bells and whistles), the more can be achieved.
I sometimes shoot real estate photographs for clients. For this, I use a Nikon D7000 with a Nikkor 10-24mm f/3.5-4.5 lens attached. If I had a different camera, I could easily use it to capture the photographs I take, but photographs of buildings and interior spaces virtually require the wider angles afforded by the 10-24mm, which captures a 109° angle of view, something not attainable with any point-and-shoot camera or camera phone, and not attainable with most other lenses. Point-and-shoot cameras, for example, tend go to about 24mm on the widest setting, and the iPhone 4 offers a 28mm field of view.
The 10-24mm is great for real estate photography, landscapes, and similar sorts of photographs where a wide viewing angle is desired. But it fails miserably as a portrait lens, due to some complex optical formulae that are too esoteric to go into here, and for sports and wildlife photography or shooting anything from a significant distance, long telephoto lenses are far more useful. Both wide angle and telephoto lenses have their limitations, as with everything, but those limitations are happily accepted as a part of photography.
So the lens does, indeed, matter, and it matters quite a bit. After all, the lens is responsible for gathering the most important element of photography (light) and transporting it to the camera for processing.
And the camera is also important, since it is responsible for resolving photons into an image, but for most usage, a relatively inexpensive, consumer grade dslr is perfectly acceptable, and its only when you want to print billboards, or shoot in the dark with very little grain, or desire easily-accessible controls that the digital camera body matters much at all.
And so I think that’s about all I have to say about the five elements of photography, for now. As I learn new things or stumble upon errors, I’ll likely have more to add, but for now a tl;dr wrap-up is in order, and that will be the subject of the sixth and final post in this series.
 I’ll refrain from going into too much detail here for fear of boring you, but in case you’re confused, the f number refers to how much light is blocked by the lens. f/1.0 is what humans see, and so f/1.8 lenses block almost twice as much light as do our human eyes. The higher the f number, the more light is needed to capture the scene properly.
 This may be changing, and likely will change as small cameras become ever-more sophisticated, easy to use, and easy to control, and there is a market for iPhone photography, with galleries hosting iPhoneography exhibitions, and stock agencies accepting photos made with camera phones. In fact, I predict that the point-and-shoot market will virtually disappear within my lifetime as camera phones become more sophisticated, assuming the world economy doesn’t completely melt down in the interim.