On Apr 5, 2005, at 10:39 AM, Village Idiot wrote:
I have questions about macro extension tubes. Does anyone use extension tubes? On what on what lenses do you usually use them? What is the difference between using extension tubes and using a macro lens? Also, why do extension tubes not work on DSLRs?
I use them, usually with a 50-135mm lens. I have the Pentax Automatic set, which supports the lens' autodiaphragm operation but does not transfer "A" exposure settings nor support auto focus. It essentially makes any A, F, FA, DA or D-FA lens into an M lens. This is not particularly convenient if the lens you're using doesn't have an aperture ring, but the lenses I use with mine all have aperture rings.
Using an extension tube is virtually the same as using a macro lens, except that the latter usually support A mode and auto focus with the current series macro lenses like the FA and D-FA models. Of course, with an extension tube, the distances you can focus too are limited by the lens' focusing helicoid in conjunction with the amount of tube extension you've fitted. Dedicated macro lenses usually run from infinity to 1:2 or 1:1 magnification steplessly.
What do you mean, "extension tubes not work on DSLRs"? Of course they work on DSLRs.
I have always been curious about extension tubes and was thinking of purchasing some (maybe on eekbay). I thought I might try them out on flowers and bugs.
I obtained a brand new set from an Ebay vendor for $75 or so.
Pick up a copy of John Shaw's "Close Ups in Nature" for a good introduction to macro work before spending money on extension tubes or any other gizmos.
Godfrey
