Question

[SlickPen50]

I would like to know if reversal rings and extension tubes can used in conjunction to one another. I have a 20mm f/2.8. Can I get better than 1 to 1 magnification by reversing the lens and adding extension tubes?

 

[Overread]

The more distance you add the more magnification you will get when adding the tubes to a reversed lens; however whilst increasing magnification it also reduces the focusing distance; so you'll fast end up reaching a practical limit of how much you can add.

However I'm afraid I can't give you any hard maths answers nor values for what you can expect, though I would say the gain is small rather than major after some rough testing. Also with a 20mm reversed or even if mounted to extension tubes direct you'll already be pushing past the 1:1 limit.

 

[kyrontf]

I've been experimenting with a reversed 28mm lens lately and it feels like I'm getting 2:1 or thereabouts... not completely sure though. As Overread said, your focusing distance goes right down the tube. I end up being just a couple of centimeters away from my subject. I imagine you wouldn't be able to extend a reversed 20mm very far, but you will certainly get great magnification just with the reversal!