« on: February 18, 2013, 05:32:39 PM »
I suspect that's the case. There is something a little odd about the design about the Canon 70-300L, though. For example, if you compare it to the Canon 70-200/2.8L IS II, both have the same specified MFD and maximum magnification (47.2" and 0.21x), but obviously the 70-300mm has a 50% longer focal length at the long end. Canon mentioned a The Tamron 70-300 VC, despite not being able to focus as close (55.1" MFD) achieves a higher 0.25x maximum magnification.
The 70-300 L has a 'floating' optical system (the 85L II has this, too). Canon stated, "As mentioned above, the use of a “floating” optical system means that as the lens is progressively focused closer, other lens elements continually change position to preserve image quality throughout the focus range. (Many lenses are optimized for best quality at or near infinity, and as focused closer, there’s a drop-off in contrast and sharpness… that’s not the case with this new lens)." It seems something had to be traded for that sharpness when focusing close, and that something translates to maximum magnification, apparent focal length, or FoV at the long end (three ways of saying the same thing, sort of).
Though I have not used the Tamron 70-300mm VC, but I've had a few other Canon lenses - and noted that at the same marked mm (eg even lower settings 100mm and 135mm on other lenses - and I think also the 300mm setting on my old Canon 100-300mm USM) - that the 70-300mm L doesn't seem as magnified.
It probably does seem like the 300mm of my 70-300mm at minimal focal distance is around 200 - 240mm-ish (depending on what other lenses it is compared with).
And yet - the good news is compared to several other tele lenses at around 300mm, the Canon 70-300mm L appears very sharp at minimum focus distance. I love it for eg dragonflies, some flowers and other details up close, / even 'tame' birds that allow me to get very near to them.
I was going to get the Tamron 70-300mm after looking at some reviews - even bought a filter to it (to replace my Canon 100-300mm USM) - but then the Canon 70-300mm L came out. I used the Canon 70-300mm L from a camera store (who allowed me to stand outside and try it) - and I was SO impressed... and I was hooked and bought one - got it for a reduced price, already just a few weeks after it was available. I haven't looked back.
The Tamron 70-300mm VC looks like a decent more budget oriented option, I was going to get this over the Canon 70-300mm nonL - as that Canon's micro USM AF isn't what I like, plus the lens build was not quite up to scratch - though they are fairly close in image quality at the tele-end.... All the best with your photography, dilbert.