I don't have the 140, so keep that in mind as you read my comment...
I think just about all the rb lenses (I have the 37, the 65, 127, 150, 180, and 360) are nice for macro; I have a couple of different extension tubes and I have been very happy with them. I don't see any really offensive distortion at close focus with any of them, well, excluding the fish I didn't get the 140 macro because the neighbouring focal lengths are so nice and you can achieve similar reproduction ratios with tubes. And they have the same f/32 minimum aperture, as I recall.
On the other hand, the rb lenses are so inexpensive now, why not pick up a truckload while you can...
My 90mm is a triplet and does not have a floating lens, the 140 is 'symmetrical' and does have a floating element. If you need optimium performance e.g. copying small objects at high resolution then I'd suggest you have to pay the piper, and get a 140mm, and set it for the magnification you are using. If you only need snaps then the 90 or 127 will do ok.
Do you make posters out of shots of spiders or other insects?
Last edited by Xmas; 10-14-2007 at 06:57 PM. Click to view previous post history.
The 140 macro is my favourite lens for the RB. I use it for macro of course but also for portraits. Because of the floating element one get impeccable performance at any distance. I did sell my 127 though when I got the 140. Just too close.