Photons Missing In Action

Started Nov 24, 2009 | Discussions thread
OP Marianne Oelund Veteran Member • Posts: 7,767
Part 1 Addendum: 70-200 VR II

One of the reviewers of this new lens model showed an example of the VR II's improved brightness, so this was one of the first checks I wanted to perform on the new lens.

Rather than going back to the original test setup (it's the wrong time of day for that), I did a quick relative measurement between the VR I and VR II.

The results indicate that the new model is indeed brighter, but not by nearly as much as the reviewer had thought: Green-channel efficiency is improved to about 78%, versus 70% for the VR I. This translates to a T-stop for the new lens of T/3.19, against T/3.38 for the VR I - or about 1/6 stop better.

Another welcome improvement is better color neutrality (more about this in part 3). The red skew of the VR I has been literally cut in half, so this means a reduced red cast with better blue saturation.

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