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Originally posted by reivax So the wireless only works with Pocketwizard? Does Pocketwizard even make triggers for Pentax?
Sekonic meters have a small recess where you can install a Pocket Wizard radio transmitter, or you can buy it preinstalled at the time of purchase. I'm not aware of any other brand of transmitter that can be installed there. The transmitter will allow you to trigger any strobe connected to a Pocket wizard device remotely, and with the 478 model you even have control over the output of certain lights.
The basic Pocket Wizard I, II and III are simple center-pin sync triggers, that is, they don't relay any TTL information and so they are brand agnostic, thus they will work with Pentax. Pocket Wizard makes another system called the MiniTT1 which is used in conjunction with the FlexTT5 to give TTL controls to Canon and Nikon flash systems. They send proprietary signals, which allows the camera to adjust the power levels based on the preflash exposure. These are brand specific, there is a Canon TT1 and a Nikon TT1, and a Canon TT5 and a Nikon TT5. I suspect that in order to use the ratio controls of the Sekonic 478, you would need at least the TT5 transceiver and the appropriate speed lights. What I don't know is whether the TT5s will work in manual flash mode. When I got to play with the 478 it seemed like all the exposure controls were in EV steps as they relate to "proper" exposure, i.e. you could set Group A to +1 and Group B to -2, but I didn't find a way to set group A to half power, and group B to quarter power. That would be necessary for the system to work with a Pentax camera since it has no way of communicating "proper" exposure to Canon or Nikon speedlights. It's possible that I just didn't find the way to switch to manual control, it is quite a complex gadget.
As far as the 358 vs. the 478, I do like the simplicity of the 358, but the 478 is a considerably more robust unit, and if it's the same price as you say, it would be the better value. It has, to my knowledge, all the features of the 358 plus the above mentioned TTL controls over Canon and Nikon speedlight with the PW system, and it can use the Sekonic camera profiling software to create custom profiles for each lens in your bag. Of course the 358 has been around for a long time, and you'll have a much easier time finding a used one than the brand new 478. I'd say either one is a good choice.