I owned a Tamron SP 90mm F2.5 Macro which offered a 1:2 ratio or 1:1 with the extension tube attached (as did the Rokkor 100/4 that passed through my hands recently). The matched Tamron SP 2X teleconverter was recommended for use with it as well and while I never did it, I assumed that you got a 180mm f5 that gave life size 1:1 - although with the degradation that the extra glassware would cause and a that a plain extension tube should not.I am green when it comes to macro work, but I have recently purchased a 105 macro. What happens to reproduction/mag ratios when you add a 1.4 Teleconverter? Or, is this not advised? Take care, Gregory david Stempel FIREFRAMEi m a g i n g
I've just bought another Tamron, having always regretted selling my last one - I intend to use a couple of decent achromatic (multi-element) close-up lenses with it (old Canon 240 and 450 dioptres) - much more convenient and less image degrading than a teleconverter although they won't allow infinity focussing. Haven't done it yet as the lens hasn't yet reached me. The resolution is better I believe because the extra optics go in front of the lens and not behind but I'm expecting some additional barrel distortion. I have a vague memory that good quality close-up lenses such as Nikons compared very favorably with the use extension tubes and bellows. I'll not get life-size but somewhere in the 1.5 range I think and I won't lose the one or two stops of a 1.4x or 2x or have the exposure problems of tubes. There are some life-size dioptres available too from mass dealers like Cambridge if you can bear to deal with them. I can't vouch for quality but stopping down a bit solves a lot of problems!
AndrewF
