How to Calculate the New MFD of a Lens When Using an Extension Tube
I recently received a comment on my popular article – The Ultimate Guide to Extension Tubes – which asked how you would go about calculating the new MFD (minimum focus distance) of a lens, once you have added an extension tube. In that original post I did include the mathematics for calculating the new maximum magnification of a lens with an extension tube, but at the time I decided not to dig deeper and explore the calculation of the new MFD itself, since the math is a little longer. The new comment reminded me about it, so I decided to …