German flash maker Metz historically used a system of interchangeable modules to provide compatibility with various camera systems, including Pentax's P-TTL. They still make some models that use that system, but they now have dedicated P-TTL flashes as well.
- 44 AF-1 — in some ways an upgrade from Pentax's AF360FGZ, with about 30% more power, a tilt/swivel head, and some advanced functionality. But, no HSS or rear-curtain sync. And, while the 44 AF-1 can function as an off-camera wireless slave it cannot act as a camera-mounted controller for other slaves.
- 50 AF-1 — effectively a small upgrade from Pentax's AF360FGZ, with about 60% more power, a tilt/swivel head, and equivalent advanced functionality (plus a few unique features). Like the 44 AF-1, the 50 AF-1 can function as an off-camera wireless slave but it cannot act as a camera-mounted controller for other slaves. This model improves on and replaces the popular 48 AF-1.
- 52 AF-1 — A new addition to the lineup, featuring a backlit LCD control panel. Unlike the 50 AF-1, this model can act as an on-camera wireless controller. Metz confirms that this model will replace the 50 AF-1, but that change is still working its way into the US distribution channels.
- 58 AF-2 — another completely-dedicated model, with top-tier power and the longest list of features of any Pentax-compatible flash. This is a minor upgrade from the previous 58 AF-1.
These flashes are available in versions specific to many different camera systems — Pentax P-TTL, Nikon CLS, Canon E-TTL, Olympus/Panasonic Micro Four Thirds, and Sony ADI. The physical differences are minor, but the flash units are dedicated, and can't be adapted or updated to work with a different system. Make sure to get the Pentax/P-TTL model.
Metz also offers the 24 AF-1 and 36 AF-5 (and previously the 36 AF-4). These flashes are made for Metz by Icorp/Tumax in China, but contain a Metz-developed firmware: Metz says they are "equipped with a special electronic technology which has been developed by Metz in Germany". These flashes basically correspond to the DSL28 Series and DSL88 Series Tumax flashes, respectively. (Currently these models are represented separately throughout this guide, but in a future update I plan to combine them where it makes sense.) Note that the Metz flashes do claim a much faster recycling time, which lends some credence to the idea that the internals are different.
The Metz-branded versions of these flashes tend to be more expensive than shell-company brands like Vivitar (which is now just a name, unrelated to the original company). In exchange for that, you get Metz's support channels and whatever advantages their firmware offers; this may not be a bad deal at all.
The higher-end flashes, from the 44 AF-1 up, are made by Metz in Germany.
In addition to these "system-dedicated" models, there's the 54 MZ-4i. This flash is discontinued but some new stock is still available as of early 2012. This model requires the SCA 3702 adapter module with firmware M2 or later. With that module, the 54 MZ-4i has features roughly equivalent to the 58 AF-1, but slightly less flash power. It also can't do Pentax's P-TTL wireless, but can act as part of Metz's own wireless auto flash system. There is a slightly older version of the 54 MZ-4i without the i — the 54 MZ-4. The differences between the two primarily apply to Nikon and Olympus; for Pentax, they're interchangeable. This guide uses the name 54 MZ-4i simply because it's newer.
Additionally, there are two module-based Pentax-compatible models not covered here: the 45 CL-4 and the top-of-the-line 76 MZ-5. These are "hammerhead"-style flashes, designed to mount on a flash bracket and connect via a cable (included with the 76 MZ-5 but not the 45 CL-4) to the shoe-mounted SCA 3702 adapter.
Metz also makes a P-TTL ring flash, the Mecablitz 15 MS-1, which operates as a wireless P-TTL slave (which would allow an on-camera controller to also control additional slaves).
The 44 AF-1 and all higher "AF" models feature a USB port for in-the-field firmware upgrades. The lower-end models may need to be sent for factory service for compatibility upgrades to match future Pentax cameras. The 54 MZ-4i is upgradable via factory updates to the SCA module.
Metz flashes used to be much more expensive than their Pentax counterparts in the US, but as the prices of Pentax's lineup have risen, that's no longer true. And in Europe, Metz models are often relatively much cheaper. The US distributor for Metz is Manfrotto Distribution (formerly named Bogen Imaging).