No I mean in practice (not theory) with the 14-42mm PZ, and definitely not stacked.
Practice pretty much equals theory, the only difference is with regards to the focus point of the camera
There are formulas you can use that give you working distances depending on focus distance, and dioptre power
Example +5 lens zoom 21-42mm focus distance 0.3m or 0.98ft working distance 4.72" - 7.87" in practice those are less as you need to account for the close up lens itself
+10 lens zoom range 2.95" - 3.94"
Those are similar to Peter on the field observation, in practical terms you won't be able to put a ruler down unless you are in the pool but what you know is enough to make decisions
When you change the zoom range the focus distance of the lens changes (goes to 0.25m) so the lens gets more range
Depending on depth of field you will also be able to use or not the lens more easily, if you have too little DOF you could have only 1 mm in focus and this is not acceptable so you have to be careful pushing the lens to the extreme limits
In real life I choose the stronger diopter based on subject size and ability to focus then work back other close up lenses to cover different sizes subjects and all possible working distances back to the bare lens.
Peter choice covers pretty much everything another option is to add an additional 2.5/3 diopter to cover also between 8-16 inches but this is not essential although it will give you a more pleasant portrait if you shoot at full zoom compared to wide end and getting closer
Edited by Interceptor121, 04 September 2014 - 12:13 PM.