People often mention 1:1 or "life-size" as being the desired standard of a "macro" lens. So what kinda pic do you get when you manage to find a bug that'll let you get close enough for a 1:1 shot?
Just for fun . . .
(NEX-7, LA-EA1, and Tamron 60mm f/2, ISO 800, f/11, shot in RAW, NR & USM applied post-conversion, 100% crop)
AAAAAAAAAAAGGGGGGGGGGGHHHHHHHHHHH!!!!!!!!!!!! :faint:
Even when you back off to 1:2, your focal plane still won't have much more than paper-thin depth . . .
(Same as above, except for f/10)
You can stop down further; but unless you're nuking the critter you'll probably have to increase ISO as I did in order to get enough shutter speed. Stopping way down and shooting at high ISO sucks out more details; so you have to figure out for yourself at what point the diminished IQ offsets proximity to the subject. Shooting handheld at this magnification compounds things, as the slightest body movement--even your pulse--can throw your focus off.
Which reminds me: the NEX-7 has almost no shutter lag, which is a huge plus when one is shooting close-ups while manually stopping down. BUT...when you add the LA-EA1, the auto-aperture makes a noticeable difference, just enough to give those involuntary muscles in your body time to throw your focus off.
1:1 is great for really tiny critters that sit still in good light (if you can find any). But for me, it's not a necessary criterion for a good close-up lens.