Thanks for your help Godfrey. > What do you mean, "extension tubes not work on DSLRs"? Of course they > work on DSLRs.
I miss read the Pentax Japan website. It actually reads "This accessory is not compatible with the *ist". http://www.pentax.co.jp/english/products/filmcamera/accessory/index35_closeup.html Which begs the question, why are most tubes incompatible with the *ist? Thanks again for your help. Derek > 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 >
