I've been looking into aquiring a macro lens. it's come down to the nikon 105mm or the tamron 90mm. I am having a hard time justifying spending double on the 105 so i'm leaning towards the 90. I just dont want to be disappointed somewhere down the line over a few hundred.. opinions on each or which direction to go? thanks, I searched for a relative thread but didn't find one and the macro section seems more like a gallery.