At 12:16 PM 3/1/2006, you wrote: ... >Quality won't be quite as good, but effective focal length is often more >important. > >Modern IF lenses, whether zoom or fixed focus, generally work better with >closeup lenses than with extension tubes, because the designers didn't have to >be concerned with lens corrections when the whole assemble is moved further >from the film/sensor plane, as the IF would be used for focussing and >correction. So even an excellent lens like the 100 USM macro performs better >with a close up lens, if you want a bit more magnification, than with >extension tubes.
Very good points. My issue has always been working distance and most modern macro lenses with internal focus reduce the effective focal length at close focus (eg. the 180mm macro is about 120mm at 1:1). The 500D, although I have never used, seems a good choice when combined with a telephoto for good working distance since more extension is needed with longer focal lengths, not to mention that some lenses do not have tripod mounts, so the added extension can make a more unstable setup. The 500D diopter also has the advantage of not reducing the light the way extension tubes do (and I believe macro lenses also loose some stops at close focus, correct me if I'm wrong). The other option is lens + extension + 1.4x converter, placing the 1.4x after the extension (placed before the extension means longer focal length and hence more extension). Of all the combinations I have tried it seems that the one that gives the easiest stable tripod mounting followed by good working distance work best for me. And if working distance is not an issue, sometimes a simple P&S or wide angle lens works great (assuming the wider background is not an issue). The other major factor for me is whether flash is used or not. I find macro flash a tough subject to master. My latest attempts have been using a cross polarization flash (polarized flash light followed but counter polarizer on the lens). I'm still in search of a good polarizer that does not burn out when attached to a 580EX flash fired at near full dump. Wayne * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
