Speedlight 430EX Misreporting (Misreading?) Focal Length.

I usually don’t shoot flash, so I am a noob as far as this is concerned.

I have a 5D III, and a Speedlight 430EX set at ETTL, shooting with a Canon 28-135 Zoom. Flash compensation is neutral, 1/200 sec at 100iso. I am shooting directly at the subject, no bounce, and no diffuser.

When I am at full 135mm extension on the lens, the "Zoom" as reported on the flash is only 105mm.

Possibly related to this, it is clear that the shots taken at 135mm are noticeably darker - by at least 2 steps - than a wide FOV shot take from the same position at 28mm. Could that be related to the error in focal length as reported by the flash?

Rad

Radtech1 wrote in post #17375672
I usually don’t shoot flash, so I am a noob as far as this is concerned.

I have a 5D III, and a Speedlight 430EX set at ETTL, shooting with a Canon 28-135 Zoom. Flash compensation is neutral, 1/200 sec at 100iso. I am shooting directly at the subject, no bounce, and no diffuser.

When I am at full 135mm extension on the lens, the "Zoom" as reported on the flash is only 105mm.

Possibly related to this, it is clear that the shots taken at 135mm are noticeably darker - by at least 2 steps - than a wide FOV shot take from the same position at 28mm. Could that be related to the error in focal length as reported by the flash?

Rad

http://www.the-digital-picture.com …te-430ex-Flash-Manual.pdf



105 is as far as it goes.

Radtech1 wrote in post #17375672
Possibly related to this, it is clear that the shots taken at 135mm are noticeably darker - by at least 2 steps - than a wide FOV shot take from the same position at 28mm. Could that be related to the error in focal length as reported by the flash?

Not at all related to your observation!

I bet that when you are shooting wider scene with 28mm lens FL vs. the narrower scene at 135mm lens FL that you are more tightly framed on a face, which is brighter than 18% grey and therefore causes the camera to prematurely discontinue the output of light of the flash because the camera THINKS 'enough light'.

Post some images so that we can do a post mortem.

Will post some tomorrow evening. I was pretty much deleting as I went, so I don't have anything to post now.

Rad