Well after playing with tubes for years (manual screw together )
As I am trying to sort out my gear I decided I needed (wanted) a set of tubes with through connections so I can use my canon 60mm macro.
So I bought a canon set from ebay for £52.99 including delivered and they came within a couple of days .
The manual is printed on a large postage stamp and will probably require macro lens to read
the tubes are 13mm 21mm and 31mm and will be used on a canon 60mm macro lens
Reading the leaflet I can just make this out
image magnification ratio= (length of ext tube+master lens advance volume)/ master lens focal length
what the heck is master volume ??
Thanks to Alex for the calculations below
Total Magnification = Lens Magnification + (Extension Tube Length)/(Lens Focal Length)
with your 60mm and a full set of tubes: 1 + 1.08 = 2.08 at infinity focus
roughly about 2.5x at minimum working distance, but I’ll stand corrected.
OK here you go this one with all tubes and canon 60mm efs macro lens
A little test to see range of focus
This one at Minimum Working Distance
This one at infinity
sensor measures 22.5mm at min distance I get as best I can figure
at MWD 22.5/9=2.5
at infinity 22.5/21.5=1.04
near enough for me
All shots taken with DAF-14C ringflash