speedlite question

Started 4 months ago | Discussions thread
kli Veteran Member • Posts: 3,986
Re: speedlite question

It depends on the speedlight. Most of the time, it will be for full frame.

But, as Richard Hopkins stated, sometimes it will be adjusted for a different sensor format based on a custom function in the flash.

For example, my Godox TT350-O, which is for Olympus/Panasonic four-thirds cameras, which use a 4/3"-format sensor with a 2x crop format, there's a C.Fn 43. If I set it to OF, then the widest angle when I pull out the wide angle diffuser panel, displays as 14mm (full frame equivalent FoV). If I set that function to ON, it then displays as 07mm. This is not in the manual, as the feature was added by a firmware update. [eyeroll].

Similarly, on a Nikon SB-900, there is a custom function (C-23) to switch between FX and DX.

Generally speaking, the cameras don't communicate sensor format size to the speedlight, so this setting has to be done explicitly on the speedlight itself. However. Most of us don't bother to worry about the specific mm being used, since that type of field of view coverage, like guide numbers, is really only accurate for direct on-camera flash. Most of us bounce, or do off-camera flash, at which point, the scene coverage you would have had with the flash on-camera pointed directly forward isn't going to matter that much. And the zoom setting on a flash is simply how focused the beam is.

All the setting really does is position the flash tube forward or back inside the head, with the longest "focal lengths" having the tube all the way in the back, and the widest angle (typically 24mm) with the tube at the front, just behind the fresnel panel.

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