Sigma
Sigma makes two almost-identical flash units:
- EF-530 DG ST — relatively inexpensive, but powerful and capable.
- EF-530 DG Super — adds wireless P-TTL, high-speed sync, better manual control, and a few more features.
Sigma's older EF-500 DG models are basically the same with about 10% less power. The older flashes flashes may need to be sent to Sigma for a free firmware upgrade for complete compatibility with current Pentax camera bodies. Without it, the EF-500 DG Super won't work in wireless mode with the K10D and newer. It's possible that the current Sigma flashes may need similar updates for future Pentax models, but they operate just fine out-of-the-box with the K20D and K200D.
Sigma makes a macro ring flash as well, the EM-140 DG, which can act as a wireless P-TTL controller.
