It's a fantastic lens, but not one I'd recommend to most people wanting to shoot macro. Especially not for someone trying macro for the first time.
If you are unfamiliar with it, the Canon MP-E 65mm Macro lens is not your typical macro lens... It's a 1:1 to 5:1 magnification lens. It essentially fills the roll of a macro bellows in older camera systems (a bellows would be problematic to implement with modern Canon electronically controlled lenses. Though some have done so... look up Novoflex, but be warned the price is high). Most macro lenses go from infinity focus to 1:1 or "Life Size" as their highest magnification... Meaning that on a full frame DSLR at highest mag they can fill the image area with a 24x36mm object, or on an APS-C crop sensor Canon DSLR are able to fill the image area with a 15x22mm object that's the same size as the sensor itself.
This is where the MPE 65mm starts... 1:1 magnification is the least it can do. It can't even focus to infinity... Or even portrait or other non-macro distances. It's a macro lens only, going from 1:1 up to 5:1 or five times life size. 5X means that on a FF camera it can fill the image area with approx. a 5x7mm object... or with an APS-C, a 3x4mm object.
It's also manual focus only (the aperture is controlled from the camera electronically) and comes fitted with a tripod mounting ring (which it needs). Even it's lens hood is unique, looking like sort of a funnel covering much of the front of the lens and one of the few Canon lenes hoods that screws in and is made of metal (and is ridiculously expensive!).
I've been wanting the MP-E for a long time... I love shooting macro. Finally got it recently, but I'm finding it challenging to use.
One big problem is finding a subject small enough to shoot with it. This lens literally shoots at magnifications we don't normally notice or pay attention to with our bare eyes. It's also not a fast lens to work with, most typically will need tripod mounting and that rules out using it with many animated subjects. At higher magnifications, the subject is only an inch or less from the front of the lens (which extends dramatically as it's dialed to higher mags).
Finally thought I'd found the ideal subject.... There are a lot of newly hatched garden snails in the yard since a recent rain. They climb to the top of a blade of grass in the early morning, so aren't too difficult to find. And they are slow moving. After all, they're snails! I found and brought a tiny one indoors, along with a leaf to "pose" it upon. Well, this first model turned out to be camera-shy and completely refused to come out of it's shell. The image below is shot nowhere near the lens' maximum magnification. It's probably about 2.5 or 3X...
Above image gives you some idea of just how shallow depth of field is. And this was shot at f16! That's the edge of the leaf, too... which is little thicker than a piece of heavy paper.
After dropping and losing above subject in the carpet (glad I'm renting!) while trying to encourage it to come out and play, I had to go outside and get another subject... A slightly larger and more animated snail (tho still smaller than the fingernail on my little finger)...
But even tho only moving at "a snail's pace", it was still a struggle with this lens to get and keep the subject framed and in focus. I had best luck moving the subject, leaf and all, but it kept crawling out of the frame, off the leaf (onto a newspaper), out of focus. The above is only around 1.5X.
One of my better shots is sort of a "snail portrait"....
Above is about 2X. Next time I hear someone whining about problems with shallow DOF in a portrait, getting one of their subject's eyes in focus, but not the other.... I'll laugh. Hey, try it at 2X (even at f16!).
At these magnifications (around 1.5X below), even a snail is pretty fast and hard to keep up with...
And somewhere along the way, the subject picked up a couple cat hairs that look like ropes at these magnifications....
I am not a fan of ring light flashes most of the time... Usually for macro I use an MR-24EX Twin Lite, or just a single 580EX or 550X with an off-camera shoe cord and some white gauze over the flash head to tone it down a bit. But at greater than 1:1 magnification the MR-14EX really comes into it's own. All the above were done with one of the Ring Lite's tubes as a primary source and the other dialed way down or completely off. The top two images used the lefthand flash tube as the primary source, while the bottom three used the righthand tube (you can see the flash tube in some of the reflections).
Overall, IMO the above aren't great shots, but sure were a good learning experience. Next time I'll look for a dead bug that won't move! I may look into image stacking software such as Helicon Focus, too. I was using Live View and sure wish my 7Ds or 5DII had articulated LCD screens. I'll also be shopping for a longer lens plate, to allow me to slide the lens back and forth more, closer to and farther from the subject to focus (the MP-E's focus ring acts more like a zoom than to focus), a standard high magnification macro focusing technique. I have a couple macro focusing stages I might try, too.
Here are a couple quick shots of the rig used to make the above shots....
It's a fun lens... but the MP-E 65mm is not for everyone (lots of patience required!)
Okay, I gotta go look for some more tiny models now. (I released the cooperative one back into the wild.)