Tamron 24-70 f/2.8 - Aperture Test

Started Dec 14, 2012 | Discussions thread
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Tamron 24-70 f/2.8 - Aperture Test
Dec 14, 2012

Hi all, i took delivery of my Tamron 24-70 f/2.8 today. As you'll know if you read my previous thread , i was concerned with the aperture issues that have been reported to affect this particular lens.

Well, i have done a quick test of the same scene. All settings have remained the same other than the aperture which i changed from f/2.8 > f/4.0 > f/5.6. When viewing the images on the screen of my D700, there definitely looks like there's a bigger shift from f/4 to f/5.6 than there is from f/2.8 to f/4. In both scenarios, it's a 1-stop shift in aperture, however the actual exposure doesn't appear to reflect this.

Take a look at the below screenshots and let me know what you think. Pay particular attention to the histograms. I'm not sure what to make of it.

The exposure differences on screen don't look too bad to me, however the histograms tell a different story. What i can also tell you is that to get the histograms to match, i only needed to add 0.7 EV to the f/4 exposure to get it to match the histogram of the f/2.8 exposure.

However to get the histogram of the f/4 exposure to match the f/5.6 exposure, i needed to dial down 1.15 EV.

I'm not sure how much of this can be attributed to vignetting.

Thoughts guys?

Nikon D700
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