Originally posted by GTS 2015
I like the idea of LED and also the fact that Pentax has clearer menu + manual buttons
The only Pentax flash I have is an old AF200T, but I do have the Metz 52 AF-1. The Metz has a red LED light for autofocus assist, but not a white LED light to work in conjunction with the main flash, so that's an advantage for the Pentax. The Metz 52 has a LCD touchscreen on the back, so it has a different interface than other Metz models, such as the 48 and I find it very easy to use, but again I have no experience with the Pentax flashes, so it may not be better in regards to ergonomics. If you use your flash outdoors in a rainstorm, WR with the Pentax flashes would also be a benefit. As far as I can tell the Metz flash implements all of the features of P-TTL and it has modelling light and optical slave modes. The biggest benefit of the Metz flash is more power for your money. Flash power is significant, especially when you use bounce flash, reflectors or modifiers and other than bulkiness and cost, there are no disadvantages to having more power. I've had mine for a couple of years without any problems.
---------- Post added 12-17-15 at 05:25 PM ----------
Originally posted by GTS 2015
what would be the guide numbers for all three flashes if we take at e.g. 85mm?
@85mm, ISO 100, the guide number for the Metz 52 is 46 meters (151 feet). The Pentax AF 540 should be around 157 feet, but I can't confirm that.