[Brightcolours]

It is all about MFD, nothing else. So... if you want more magnification, you select the lens that is shorter. With a 12mm extension tube you then will get closer. The TS-E 24mm f3.5 II is not a good candidate, as it is too long and focus will move past the front element <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />.



The PC 24mm is not the shortest lens either. The Sigma 20mm f1.8 and 24mm f1.8 macro both will do better with a 12mm extension tube attached. And yes, both these lenses are a lot better and versatile than the "interweb" would have one believe.



For this reason I will try the Canon 24mm f2.8 sometime, it is very compact and has good optics. It will reach 1:1.5 (with 12mm tube). With a 25mm tube it can reach 1:1, but then the subject will be against the front element.

The Sigma being 3.5 cm longer than the Canon makes that even though the Sigma can focus closer, it will not get better magnification than the Canon with 12mm extension tube. But 20mm still is quite a bit wider than 24mm...



Plus for the Sigma is the magnification RANGE, though. The Canon 24mm will do 1:6 without tube, 1:2 to 1:1.5 with 12mm tube (and 1:1 with 25mm one).

The gap between 1:6 and 1:2 is big and not very flexible.