Quote Originally Posted by Daniel Browning


To me, saying "extension tubes lose DOF" is like saying "race cars cause fast driving". It makes it possible, and that's how most people use them, but it doesn't really cause it, per se. To illustrate:

Fast driving is caused by the driver accelerating to high speeds. Race cars make it possible to achieve high speeds. Another way is stock cars. It's possible to drive race cars and stock cars at normal speeds, but usually people buy them to drive fast.

Losing DOF is caused by focusing close. Extension tubes are just one way to focus close. Another way is to use a macro lens. It's possible to use extension tubes and macro lenses at normal focus distances, but usually people buy them to focus close.

Am I being too pedantic?


I'd like to say "yes, yes you are". Race cars make it possible to achieve high speeds, but they can still go slow (they have to go slow to stop to fill up, change tires, go slow again before going fast). Extension tubes, on the other hand, FORCE shorter focus distances, and therefore FORCE short DoF. You say it's possible to use extension tubes at normal focus distances, but it's a fact that infinity focus is lost, and I've never left an extension tube on "for the fun of it". The tube is a very limited-purpose tool.