Using 550EX as master and 420EX as slave

Hello:

Just started using the 550 as a master to trigger my off-camera 420ex. When setting the 550 as the master, the distance scale on the back of the 550 dissappears.

Does the addition of the 420 as a slaved-strobe somehow disable some of the functions of the 550?

Thanks.

This is just an educated guess on my part but the distance scale is useful only when you are using the 550EX by itself and when it is mounted directly on the camera (or a flash bracket). You know, GN, aperture and subject-to-flash distance and all that?

When you set the 550EX to Master, the assumption is that there will be another flash (the slave) in the equation so now we have now idea what the resultant GN is nor the distance that the other flash is placed from the subject, making the distance scale useless.

When you use the strobes as master/slave they both zoom to 24 mm lens coverage settings by default. If you're referring to the scale which displays the effective range of the flash, both the change to a fixed coverage angle and the addition of multiple flashes to the system would render its' display meaningless, since it can't tell what other flashes are being used or allow for the ratio settings until the pre-flash for Ettl.

Can you change that? It's kind of a bummer for me, since I need more like 300mm coverage...

You can manually adjust the zoom, it's just what they chose for the default (IIRC 24's the number; I don't think it's 28). Add-on flash focussing devices would work too. I don't think the zoom affects the separation you can have between the flashes without losing communication though. Somethng like 15-20 ft. outdoors, isn't it?

using the 550ex as master and 420 as slave

Hello:

To expand on this a bit, does anyone know if the new Q-Flash (Quantum) will work as a master or slave when you purchase it's Canon TTL module??

Thanks again for the suggestions!