Jeff….They didn’t double the granularity, they simply started from a different number. For example, on my Explorer 2, target ID goes from 00-31 on the Conductive side AND on the Ferrous side. The same is true on my Explorer SEPro, so the available pixels and target coordinates are the same. The difference is that on the earlier Explorers, if you are in the adjustment screen at wide open Iron Mask, the number should indicate “-16” and will move toward “0” as you apply progressively more discrimination. On the Explorer2 and earlier, in Iron Mask you can only disc out approximately half of the screen. On the SEPro, instead of indicating “-16”, it indicates “AM” (All Metal). This is kind of like a “32” on the Ferrous side, but isn’t used in any target IDs. Then it goes to -31,-30,-29 etc until you get to 0, which actually allows you to disc out the ENTIRE screen. Starting with wide open Iron Mask, moving the disc 10 places to the right on either machine gets you to the exact same amount of disc.
Explorer2 and earlier (-16+10=-6)
Explorer SE and SEPro (All Metal+10=-22).
I‘m sure this is as clear as mud and way late, but there it is.