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p.1 #4 · p.1 #4 · Extension tubes and (different) lenses - effects or not? | |
This is my understanding, given with the knowledge that someone with more accurate information will jump in to correct me, but no one is answering yet, so I'll get started...
Indeed, every lens has different characteristics (MFD, depth-of-field, etc.) when combined with extension tubes, varying with the size of the tube(s), the length of the lens, and the aperture used...apparently, no lens will retain infinity focus, and the minimum focus distance (mfd) is reduced. Admittedly, I couldn't tell you exactly why/how this works, but I do know that UWA lenses may not focus at all, since the minimum focus distance may end up within the lens itself - mfd is measured from the sensor, after all...
Here's a handy table of reference for extension tube use with different lenses:
http://www.bobatkins.com/photography/eosfaq/closeup.htm
Also, Brian Carnathan always mentions the magnification values of tubes in his reviews of Canon lenses, here:
http://www.the-digital-picture.com/
As I said, many will have clearer information, and will jump in soon, I'm just getting the ball rolling...
Jerry
(see, it happened while I was still typing! )
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