This lens is capable of generating full-frame images up to five times the size of the subject natively. It is capable of generating full-frame images up to ten times the size of the subject with the addition of a 2× Extender teleconverter. Minor additional magnification can also be achieved by the addition of a Canon or third-party extension tube. It exhibits an extremely low depth of field, a maximum of 2.24mm at f/16 at 1× magnification, and a minimum of 0.048 mm at f/2.8 at 5× magnification. It is sensitive to faint vibrations, with slight breezes or imperceptible movements having potentially significant effects on image focus. A tripod is generally required when using this lens, but handheld photography with this lens can produce images with good focus when a flash is used.
The technical specifications indicate an aperture range of f/2.8 to f/16, which is the value displayed by the camera body when the focus is set to infinity. However, the MP-E 65mm lens cannot be set to infinity,[1] so its effective f-number depends on the magnification ratio chosen, and is calculated as[citation needed]:
For example, at 3× magnification with a listed aperture of f/8, the effective f-number is 8 × (3+1) = f/32. Hence, the lens may have an effective f-number of f/5.6 at 1× magnification to f/96 at 5× magnification. When a Canon Extender EF is attached, the usual f-number compensation is applied (in the previous example of f/5.6 at 5× magnification, the effective f-number would be f/180 if the Canon Extender 2× was attached to the lens.) Magnification is continuous, not discrete, so fractional magnification values (for example, 2.3×) are possible. The lens circuitry communicates the chosen magnification ratio to the camera body, so it will be recorded in the image metadata. It can be viewed by Exiftool version 8.11 or later.
Canon recommends using either aperture priority or manual mode when using this lens.[1]
