On a recent group photo shoot, a fellow photographer asked me to come up with my dream list for macro photography. I thought this was a fun endeavor, so I decided to put one together. First, keep in mind that this is a "dream list". You can take macro photos at a very high level with other gear, but if you want the best of the best this is what you should have. Also, of course skill is more important than top level gear, so just because you have the gear does not mean you are guaranteed great shots. In fact, in macro photography I think the case is the opposite. While a top photographer can take much better shots with top end gear than he would with a point-and-shoot with macro capabilities, the same is not true of a newbie. Unless you know how to use the gear, you are more likely to take better shots with a point-and-shoot with macro capabilities.
Also note that this list is Canon specific, as that is the brand I use. Most of the lenses (except the MP-E 65) have Nikon equivalents though, so the list applies almost equally well to Nikon photographers. Also note that I will not specify a camera model, as they change often and in the case of macro the only real difference you will see is resolution.
Canon 180mm 3.5L - This is the highest quality macro lens that Canon makes, and also has the longest reach. This is the perfect lens for shooting bugs that are afraid of you, or ones you are afraid of. Note that I did not include the excellent Canon 100mm 2.8 here, because with the other lenses I list here it's not very useful.
Canon MP-E 65 - This is one of the most unique lenses in Canon's lineup (there is no equivalent from other manufacturers) and allows you to go from 1x-5x. It is one of my favorite lenses but is also extremely tricky to use. The MT-24EX is a requirement when using it for anything non-stationary and the lens has no focus. Diffraction issues also arise due to the extreme magnification at high levels. Nevertheless, this is one incredible lens when used correctly.
Canon TS-E 90 - This isn't really a macro lens but it does have macro capabilities and with its tilt shift features allow for some of the most interesting macro shots out there. I have heard some photographers call this the best macro lens out there and it certainly is one of the more interesting lenses to own.
Canon MT-24EX - There's a lot of discussion out there between this flash and the MT-14EX. The primary issue people have with the MT-24EX is the harsh light. The primary issue people have with the MT-14EX is flat light. I did have issues with the MT-24EX with harsh light, but after adding a specialized lens hood and diffusers I no longer have issues here. The MT-24EX nevertheless requires understanding light and a newbie may get frustrated with it. Still, the flexibility it provides leaves the MT-14EX in the dust.
Gitzo tripod - Ok, so I'm listing Gitzo simply because it is the best, but the fact is you won't see the difference between a Gitzo and many other manufacturers when it comes to macro photography. I use the Gitzo 1348, which provides a great balance between a tall height (I am 6'5") and the ability to go very low to the ground. In general, you want a tripod with either no center column or a removable center column to get close to the ground. The legs should be sturdy and should also be able to swing out so they are almost perpendicular to the ball head. Keep in mind that a tripod is great for flowers and things that don't move, but is practically useless for insect photography.
Top end ball head - There are several companies that make great ball heads - probably the three best being Kirk, Really Right Stuff, and Markins. I use the Markins M20 and have no issues with it. I strong ball head is quite important, as some of the macro lenses are a bit on the heavy side and when you add a big camera, L bracket, macro rail and other things it can get a bit heavy. Add this to the fact that sometimes you will point your camera straight down and you need a ball head that can hold some weight solid - because even slight vibrations will effect the shot.
Macro rail - In macro photography, you do not use AF but instead move the camera back and forth until it is in focus. For this reason, if you intend to use a tripod you will need a macro rail. If you are using a lens like the MP-E 65, the majority of macro rails on the market are too course. The only two rails that will support the MP-E 65 are the Kirk and Really Right Stuff macro rails. The Kirk has the advantage that the plate can be turned 90 degrees to support either a camera plate or a lens plate. The RRS rail requires an extra adapter to do this. The RRS rail has finer control, but I have had no issues with the using the Kirk rail with my MP-E at 5x. The RRS rail is also more expensive due to the extra adapter.
Canon MP-E 65 lens hood - This lens hood (one of the weirdest ones I have ever seen) is very helpful in reducing light bouncing into the lens when using the MT-24EX flash.
Sto-fen Omni-bounce set for MT-24EX flash - These diffusers dramatically improved my light when using the MT-24EX.
Rocket blower - Macro shots display every piece of dust on your sensor. This is a great way to remove the larger dust pieces.
Sensor cleaning solutions - Photographic Solutions make the best known ones, such as Eclipse. Lenses such as the MP-E 65 will show dust you never dreamed of and the rocket blower will simply not remove it. For this, you will need to do regulary sensor cleaning.
RRS flash bracket with extra mount and extension rails - With the MP-E 65, you will not have the need to improve upon the ring included, as all of your subjects will be incredibly close. When using lenses such as the 180mm though, you may want to move lights past the lens for some creative effects. RRS makes a great, lightweight, set of brackets and extension rails that can enable you to do this.
Canon 72C adapter - You will need this to fit the MT-24EX on the 180mm lens.