The E640’s best-in-class feature is its huge 9-stop power range: Dial-in power from 2.5Ws to 640Ws.
The US-based manufacturer and distributor of the Einstein E640 monolight is Paul C. Buff, and he’s created one of the most capable monolights on the market, including a complete array of low-cost modifiers, AC inverters, and even a fully programmable radio triggering system. The Einstein E640 has a power range almost unrivaled by any other strobe in its class, ranging from just 2.5Ws to their claimed maximum power output of 640Ws.
And, unlike the BowensGEM receiver, the PocketWizard PowerMC2 receiver for the E640 supports full-HyperSync operation, whereas the Bowens receiver does not. Also, the Bowens, while very sturdily built, weighs in a bit heavy at 6.4 lbs. (over twice as heavy as the Elinchrome D-Lite units). It seems that every system has its trade-offs (some of them, significant). So, choosing the “best” monolight for your particular needs isn’t necessarily a cut-and-dried process. The Einstein E640, while feature-rich, with excellent specs, is not without its own idiosyncracies. Although true of most other monolights as well, boom-mounting an E640 would render all of its controls upside-down, which would be particularly user-unfriendly since all the E640’s info is displayed on its LCD screen. Solving this problem requires a special project requiring some drilling, and a special speedring (one only available from OEC Camera on eBay). Also, the E640’s touch-screen interface has been reported to be a bit touchy.