I am contemplating to buy a 85mm 1.8, but since I have a Tamron 90mm I am in doubt if I should do it. I would love to hear experiences of those who have both and why they use their 85mm instead of their 90/100/105mm. I was playing with the idea of buying in about a years time a D700 for its unbelievable high iso possibilities when the prices have gone down a bit and I have saved enough. I chose my lens collection based on the focal range for a DX camera and will have to adjust to how they will work on a FF camera. I also find the D700 a bit too heavy a camera for me and am therefore now contemplating to get a D90 and a 85mm instead. My thought is that together with better high iso possibilities of a D90 and a faster lens it will compensate for me somewhat the loss of the high iso possibilities I would have had with D700. A 1.8 lens lets in about three times as much light as a 2.8. I would then have a 30mm 1.4, Nikkor 50mm 1.8 and a Nikkor 85mm 1.8 for low light situations.