The Canon MP-E 65mm Macro Lens is an extreme macro lens. And it is unlike any other Canon lens I have used to date. And I recommend that you read the manual for this lens - it will help you understand its uniqueness.
Canon lists the focal length for this lens as 65mm. It is, but disregard this number for all intents and purposes. Think 1x to 5x magnification. Think 1:1 to 5:1. This lens starts where typical macro lenses stop.
The Canon MP-E 65mm Macro Lens barrel is even marked with these numbers. As you turn the ring (over a full turn is possible), the 1x, 2x, 3x, 4x and 5x notations are easily seen (as are focus working distances).
I should probably tell you right up front that the Canon MP-E 65mm Macro Lens is a manual focus lens. This is not a bad thing for a macro-only lens as this is how macrco lenses are frequently used anyway. Turning the focus ring does indeed bring the subject into focus, but this effect zooms in and out on the subject (other lenses do also, but it is very noticeable). You can either set the magnification you desire and move closer/farther away to focus (magnification priority), or you can change the magnification by turning the ring until your subject is in focus.
Well, it will focus on your subject as long as you are within the Canon MP-E 65mm Macro Lens' tiny focus distance range. Starting at 1x, the MP-E subject is in focus at a slightly more than a 100mm working distance. By 2x, the working distance drops to 63mm. Continuing on a distance curve, the MP-E allows only 41mm of working distance at 5x. You can forget trying to grab a portrait with this lens - unless the portrait is of an insect or something similar.
And while I'm on the subject of focus, DOF (Depth of Field) is another topic I want to expand on. DOF on the Canon MP-E 65mm Macro Lens ranges from 2.240mm (1x, f/16) to .048 (5x, f/2.8). At 5x and f/16, the MP-E gives a minute .269mm DOF. This sounds worse than it really is as a grain of rice (says Canon) can fill the viewfinder. Subjects this tiny generally do not need as much DOF as something like a flower.
The Canon MP-E 65mm Macro Lens is advertised as an f/2.8 lens. And it can be set down to f/16. F/2.8 is fast, but many lenses can be stopped down well beyond f/16. Well, truth is, the manual gives a chart of the "Effective" apertures for this lens. To calculate these, use this formula ...
Effective Aperture = (Aperture Setting) + (Aperture Setting x Magnification)
So, even selecting f/2.8 at 1x magnification results in an effective f/5.6. Selecting f/16 at 5x results in an effective f/96. Selecting f/5.6 at 3x results in an effective f/22.4. Get it? In reality, the camera takes care of this effective aperture change with its auto exposure. What you will notice is that the viewfinder gets very, very dark by 5x magnification. To make this worse, you are often shading the subject with the very-short working distance setup.
With effective apertures this tiny, a huge amount of light and/or a long shutter speed is required for adequate exposure. Another issue is the jittery-ness of the camera at these magnifications. Basically, you will need an very stable tripod and a motionless subject - or you need a flash.
A flash is the best solution for most subjects. The extremely fast and bright flash will stop camera shake (even handheld) and subject motion. the Canon Macro Twin Lite MT-24EX Flash is an excellent flash solution for the Canon MP-E 65mm Macro Lens. When shooting at or approaching 5x, there are not many other good solutions.
Even when using a flash, keeping the subject in focus can be a challenge - especially if it is moving. Handheld shots can work if you are very steady. When shooting at 5x, having something to rest on is extremely helpful. A good tripod is very helpful, but getting it setup for such a tiny DOF and subject can be a bit challenging. A Macro Focusing Rail is very useful with this lens. The rail allows easy micro adjustment of the entire macro setup.
The build quality of the Canon MP-E 65mm Macro Lens is very good. It is a very solidly built piece of optics. Inside, a UD element is utilized. Retracted, the MP-E is short, extended it is long.
Pictured above from left to right are the Canon MP-E 65mm 1-5x Macro Lens (extended), Canon MP-E 65mm 1-5x Macro Lens (retracted), Canon EF 24-70mm f/2.8 L USM Lens and the Canon EF 180mm f/3.5 L USM Lens.
A rotating and removable tripod collar is included on the Canon MP-E 65mm Macro Lens. Unfortunately, it has so little clearance on the camera's hand grip that it will not rotate completely with a Wimberley P20 Lens Plate mounted on it. It barely clears the bottom/front on my Canon EOS 1D Mark II. While a little annoying, I didn't find this to be a significant issue in real use.
On the performance side, at 1x, the Canon MP-E 65mm Macro Lens was soft at f/2.8 but improved until very sharp at f/5.6 through f/8. Performance once again degraded from f/11 to f/16. Performance within each magnification mirrored the 1x performance aperture to aperture, but slowly degraded as magnification increased. Sharpness was not great even at f/8 at 5x.
The Canon MP-E 65mm Macro Lens brings a whole new world of subjects to you! Viewing 5x magnification images on a computer monitor is very fun. It is not hard to see the 8 eyes on a Spider. You might have trouble getting all of its 8 legs in the frame though!
Dime at 1x magnification over a Dime at 5x magnification.
The Canon MP-E 65mm Macro Lens also enlightens you to a whole new world of sensor dust. Make sure your sensor is spotless - or plan to spend a lot of time with Photoshop's healing brush!
This Canon MP-E 65mm Macro Lens inspires creativity. I don't recommend this lens for beginner macro photography as it might inspire frustration. With patience however, you can create highly attention-grabbing images!