TEST: DIY macro lens

syamastro posted a photo:

This is the first test of my "macro lens": an old manual lens 50mm f/2.0
stacked in a reversed position on top of my lens Canon 135mm f2.0L. To attach
the two lenses, I bought a 52mm-72mm ring coupler from ebay (~5$). The
magnification factor of such compound lens is 135/50=2.7:1. From my tests,
the sharpest photos are when both lenses are set at f/5.6. The resulting DoF
is pretty thin, so I used the "DSLR bracketeer" software
(http://www.milosparipovic.com/dslr-bracketeer.html) to shoot a sequence of
32 shots with gradually changing focus, and then used Enfuse software to
combine them in one large DoF shot using the focus stacking technique.

This shot is only slightly (by 30%) cropped. You can see from the full size
version that the resolution is pretty decent.

Big advantage of this macro technique compared to others (like extension
tubes) is that the quality can be better (because both lenses work in the
optimal regime, with the focus between MFD and infinity), that one has
auto-focus control (so DSLR bracketeer can be used for automatic shooting),
and that the angular size of the object doesn't change as one is changing the
focus (because my lens 135L uses internal focusing, IF; when you use a macro
bellow, angular size can change a lot).