I posted this awhile back on another list and I actually managed to find it again. This was actually intended for extreme macro (5:1 and beyond) but the info also applies to 2:1 (wide angle for me).
When shooting at 2:1 +, the field of view is very narrow and if you try to use wide beam strobes most of the output will not be concentrated on the subject. I have tried using Nikonos SB 104s and Ike 200s but the size of the strobe made it very difficult to position and this resulted in many underexposed shots. Narrow beam strobes although usually a lot less powerful work much better for supermacro. the smaller narrow strobes can even be placed in front of the port face sometimes within a couple of inches of the subject. The Ike 50 and the SB 105 are well suited for this. Smaller strobes will also allow you to streamline the rig which is very important when you are trying to shoot something 6 inches or closer to the front of the port.
I gave up on dioptors for high magnification shots because they reduced the lens to subject distance so much, it became very difficult to place the strobes so that most of the beam would be focused on the subject. By stacking teleconverters combined with the Nikon 105 mm, I have managed to shoot in excess of 10:1, using only 2 SB-105s. If at all possible try to match a port that will end up with the lens almost touching the inner port face at max magnification. This will add some precious working distance.
Finding the subject can be the most difficult task, therefore, Get a small bright lite with a narrow beam (Ike PCA) to use as a spotting lite. I always adjust the light so that it is concentrated where the subject will be in best focus. I do this before approaching the subject by finding something that is easy to focus on like a relatively flat surface, making the adjustment and then moving in on the subject. I then focus the light on the subject while looking over the camera,I then try to hold the camera still and peer through the viewfinder to do the final search to lock in on the subject
If you do choose to use dioptors, only use the high quality multi element type. Kenko also has a good assortment to choose from. You may have to use a stepping ring with some lenses since these high quality dioptors are not available in every diameter and strength combination.
As for camera settings, I shoot everything in full Manual.
In the past I was quite limited on what I could do due the limitations of film based system. I am quite curious as to what the Fuji S-2 will allow.
This I will find out next week on Guam! Woo Hoo!!!.
In the future, I hope to try out my Nikon 200 mm micro. With that lens, I may once again try using dioptors if the reduction in working distance is acceptable. I am also have a custom ring made so I can mount small strobes directly to the port, This will allow the use of 4 strobes (sync/slave) or more without making the rig too unmanageable.
Sorry for the long winded post
Kindest Regards
Chris Bangs