Why can Sony NEX pop-up flash not trigger external flash?

[Gog]

Hi,

I own a Sony flash (HVL-F43AM) and Sony DSLR (A390), and I was quite excited when I found out that I can use the camera's pop-up flash to remotely trigger the big one. Now, from what I've been reading it seems that the pop-up flash of Sony's NEX-7 is not able to do that (dito probably for the other NEX cameras with builtin flash) , and I'm wondering why. Is there a technical reason for dropping this very useful feature? How does the triggering work anyway?

Thank you!
Georg

[Manfred M]

Looking at the flash manual, it looks like Sony built the unit without the ability to be optically slaved. It is radio control (a very nice feature to have), but that means that the camera that you are using has to have a built-in compatable radio transmitter in the camera for it to work. It looks like the NEX does not have this feature.

Is there a work-around; yes? You will have to buy an optical slave attachment, but your flash will not be able to communicate with your camera and will have to be set manually.

Something like this will likely work for you: http://www.amazon.com/Seagull-SYK-4-.../dp/B0028DM1YA

[Gog]

Thanks for your reply, and sorry for a mistake in my original post: the flash I own is HVL-F43AM, not HVL-F42AM (I will edit the original post in a minute). The manual is available here:
http://pdf.crse.com/manuals/4278307112.pdf

On page 47 it describes the wireless options, the relevant being:

[A] Wireless flash photography (HVL-F43AM: off-camera flash)
The camera's built-in flash is the controller (the flash that emits control light) and
the HVL-F43AM is the off-camera flash (the flash that is away from the camera).

Since it says "control light" I suppose that the triggering works optically.

[Manfred M]

Unfortunately, I don't know the Sony system at all, so my answers are based on my working with Nikon gear, I assume that the two systems are somewhat similar. The use of the term wireless is a bit strange, as that usually infers radio control.

The way that these dedicated flashes work in off-camera mode is that the camera has to be set into a control mode through a menu selection. On my Nikons, this is called "Commander" mode and I can set flash intensity of the off-camera flash right from the camera. When in Commander mode and the external flash is set in slave mode, the camera sends a sequence of light pulses just before the camera fires to the flash telling it how to operate. The camera through the lens metering system controls the flash during the shot as well. If this mode is turned off on the camera, the off camera flash should still tigger, but has to be set manually, as there is no communication between the camera and flash.

In this traditional slave mode, your camera shouldn't care where the triggering flash comes from, but should fire anyways; so there is no reason the NEX wouldn't fire it. I would simply test it to see what happens.