Help with the 420 EX in non-TTL use

Started Apr 15, 2013 | Discussions thread
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Help with the 420 EX in non-TTL use
Apr 15, 2013


I was hoping that someone who uses  or is familiar with the Canon 420 EX can assist me in understanding how to use it on a non Canon camera where TTL is not a possibility.

I am looking to use the 420 with a Panasonic fz 200. In not being TTL compatible -  I will need to determine the guide number GN to use. The 420 EX manual provides a GN chart that is based on the focal length of the flash zoom.

Here are my questions,

1. Since the 420 EX is a zoom flash and TTL is not available, I am assuming the flash is not zooming, is this correct?

2. The 420 has no manual controls.  On the back of the flash there are led lights corresponding to  the various focal lengths  of the zoom: 24 mm (GN 23) to 105 mm (GN 42) (see insert). Once the camera and the flash are turned on, one of the lights illuminates. FYI - if the flash is turned on first, the Flash Coverage of 24 is lit. If I turn on the camera first, then the flash, 35 is lit. Is this indicating that the flash is using that corresponding GN (23 or 31) ?

I am just looking to see what the flash is doing to ascertain the GN. Then I can build a chart based on a GN and provide aperture and flash/exposure compensation to get the lighting as best as possible.

Thanks for any help you can provide.


420 EX GN Chart

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