Macro Lens ƒ2.8 65mm 1-5x
This Macro lens from Canon is in effect a lens with built in helical extension tube, so as you turn the body of the lens the tube length increases thereby increasing the magnification. Much more convenient than having to add individual extension tubes, focusing is manual just select magnification and move lens - note focus rack, auto exposure works, so you can focus at the widest aperture ƒ2.8 in this case.
The background image was shot in ambient light using remote release with the lens on 1x (1:1) i.e. the subject is reproduced life size on chip. If a full frame back was used it would still be life size there would just be more of the subject shown, however there is a 'pixel factor' you need to take in to account.
The full frame 5D is 4368 x 2912 pixels RAW on a 35.8 x 23.9mm sensor and the 40D is 3888 x2592 pixels RAW on a 22.2 x 14.8mm sensor. So pixel for pixel reproduction introduces a magnification or 'pixel factor' due to the much denser packing on the smaller sensor; if my math is correct it gives a pixel density of 122p/mm on the 5D and 175p/mm on the 40D 175/122 = 1.4x pixel multiplier which means it is possible to have a 1.4m print with the same density as a 1m ?
You just need to make sure its not empty magnification!
Background image 1:1 ƒ16 | 0.6s ~ Foreground image 10Mpix compact.