speedlite question

Started 4 months ago | Discussions thread
Richard Hopkins
Richard Hopkins Regular Member • Posts: 476
Re: speedlite question

Doug Haag wrote:

I have happily used a totally manual speedlite for literally decades (i.e no TTL, no fine tuning of power output in manual mode, etc). I recently upgraded to a modern speedlite with these features. But I have a question about one new feature to which I cannot find an answer in the user manual.

The device has the ability to change the flash coverage through a Zoom setting measured in millimeters of focal length (e.g. 20mm, 24mm etc,) But it doesn't indicate whether this relates to the field of view for that focal length on a full frame or other sensor size.

Since the TTL mode reads the camera's aperture and iso setting perhaps it is smart enough to know the sensor size of the camera to which it is attached and the flash coverage is adjusted accordingly.

So does the 24mm Zoom setting, for example, match the field of view of a 24mm lens on a full frame camera, but when attached to a crop sensor camera its coverage is equivalent to the field of view of a 16mm lens? Or is that setting equivalent to the field of view for whatever camera and lens combination it is matched with? If the latter applies, when it is attached to a crop sensor camera, the coverage at the 24mm Zoom setting would be the same as a 36mm FOV on a FF camera.

If, as I suspect, the Zoom setting is based on full frame equivalence regardless of the camera to which it is attached, I need not set the Zoom below 24mm when it is used with my 17-50mm lens on a crop sensor Nikon, At that setting, the FOV of the flash would be equivalent to 16mm on my camera.

As you suspect, it is based on full-frame focal lengths, and may convert to equivalents automatically, or via a custom functions setting, or not at all depending on the camera and flash. Check the handbook.

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