Lens coupling query

Hi guys, I thought I'd dip my toes in the macro waters by getting a couple of lens coupling rings as a cheap introduction to see if I like it.

I understand the formula for magnification between the two lenses [Ie put a 50mm on a 300mm lens and you get 300/50=6:1 magnification], is there something similar as regards focusing distance?

I've got my fifty and also an old MF 28mm f/2.8 I can use on top of my lenses.

Thanks for any advice.

I think there are some equations for focus distance but they always seem to require info that you don't have to hand. Think you are better off playing with the camera on a table with a well lit vertical target (eg cereal box) and trying out some combinations by just holding or lightly taping a reversed lens in place. Think you will find in most useful cases the focus point varies from about 0.5 to 3 " in front of the reversed lens.

Brian V.

Thanks for the feedback Brian. My rings should be here fairly soon, so I'll play with the various combinations and see what I get I guess.