Canon 24-70mm not constant 2.8?

[Kim Frank]

I just shot a Musicvideo with a lot of fast Zooms.
In post I recognized a brightness loss about a half stop
on the longer end of my new 24-70mm Zoom.
Made CC really complicated.
Is that normal (I don't hope so!)

[Scott Crawley]

The 24-70L is consistant from end to end. I don't know of any reason why the lens would loose light on the tele end, and it doesn't stop down on the wide end.

[Kim Frank]

Okay thanks...
Than I picked a bad one.

[Roberto Lequeux]

Others here have reported the similar findings.

[Kim Frank]

Called the shop where I bought it and he tried to explain to me, that this is normal.
He said that this would have to do with the film modus of the 5DII.
What to believe.
I'm going to give it a test picture vs. film,
but maybe someone knows.

[Kim Frank]

Others here have reported the similar findings.

Thanks Roberto, but does "the same" mean it's normal or its a faulty lense`?

[Roberto Lequeux]

the film modus of the 5DII.

The Whha?!

Smells like

Thanks Roberto, but does "the same" mean it's normal or its a faulty lense`?

It would seem that it is "normal". I'll try to post a comparison for you.

[Roberto Lequeux]

These are 20% horizontal but full vertical crops with the same region roughly in the same area of the image circle. Same distance and lighting of course. RGB measurements from the PS eyedropper tool.

[Kim Frank]

Thank you very much!
That's exactly what I mean.
And I always thoght it would be constant.

[Roberto Lequeux]

Might be worth pointing out the obvious, one measurement won't be an very accurate quantification of the light loss.