Tamron 90 Macro VC - exposure

Hi all,
after lots of debating and trials I ordered the tamron 90mm vc macro lens which arrived yesterday. Compared with the sigma 105 OS I tried the lens is lighter, quieter, and makes all in all a very good first impression. The only concern I have is concerning the exposure. I feel that the lens over-exposes slightly. Using the compensation, -.3 to -.7 the results are very pleasing, however i would be interested to hear from anyone else who may have experience with this lens, if you also notice the exposure with this lens is a little on the high side.

Thanks
Martin

I was not there to see, so of course, I have no clue what we are discussing. But, even assuming on a tripod of the same scene, 90 mm will see a little wider view than 105mm. Even the center spot metered is a little wider. So I am wondering what the two lenses actually saw, and presented to be metered? My guess is that probably would explain things.

More white area in the metered area will tend to underexposure. More black area in the metered area will tend towards overexposure.

See How light meters work Could that explain anything?

Try the comparison again, on a scene of a blank wall, that will be exactly the same all over, in both pictures.