Not having touched/experimented with a very vast array of lenses yet, I'm a bit confused about "full-time manual focus". I know what it is, and what it's for; I understand its use... Still, there seem to be differences in it.
Most or all autofocus-able lenses (at least from Canon) have an auto focus / manual focus switch on the lens itself. 'Primitive' lenses (some cheap kit lenses among others) do not allow manual focussing at all as long as this switch is on "auto focus". This means that the focus ring will not turn while this switch is on "af".
Now as I understand it, for lenses with full-time manual focus, while in "af" mode and after focussing, you're able to adjust the focus by turning the ring.
The confusion that I have is what happens when I turn the focus ring on my 70-200 f/4L IS lens (my only L lens by the way), without autofocussing first. The focus changes perfectly. It's as if the lens is in manual mode; no need to focus first, you can always manually focus even without half-pressing the shutter, even with the camera off, while it's on "af" mode (even though that's useless because when half-pressing the shutter it'll first AF first again anyhow). But when I once "felt" a 135mm f/2L, the focus ring turned but did nothing unless you had autofocussed first.
So there seem to be at least two different "types" of full-time manual focus (perhaps more if counting micro USM seperately, but the two lenses mentioned above both have ring-type USM). One that will always make the focus ring focus, regardless of af/manual mode; and one that will allow manual adjustments only after focussing with AF. What is it that distinguishes these two? Is there a name for it, is it possible to see which lenses have the type of FTM that my lens has, and which have the type that the 135mm has?