Several of us GAS sufferers are eagerly awaiting the arrival of the new 40-150mm f/2.8 lens. The current Oly m43 40-150 is a little beauty though and it has plenty of admirers. I have been using it recently on the E-M5 for rugby as a second camera on bright dry days so that I can get the action when it comes too close for the heavy artillery (usually the E-M1 with 50-200 plus EC-14).
The general comment about performance of the little 40-150 is that it's pretty good in general but can be iffy at the long end and wide open. Here is one from a couple of weekends ago taken at full stretch - 150mm and f/5.6:

I can't see too much wrong with it! It is a crop of about 3/4 of the frame. With the central subject the corners are out of focus anyway so we can't tell how sharp it would be, and it doesn't matter. But certainly in this shot it is as sharp as I need it, and for the price it far exceeds reasonable expectations.
Now, if only it were weathersealed and f/2.8 for the winter.....
John
The general comment about performance of the little 40-150 is that it's pretty good in general but can be iffy at the long end and wide open. Here is one from a couple of weekends ago taken at full stretch - 150mm and f/5.6:

I can't see too much wrong with it! It is a crop of about 3/4 of the frame. With the central subject the corners are out of focus anyway so we can't tell how sharp it would be, and it doesn't matter. But certainly in this shot it is as sharp as I need it, and for the price it far exceeds reasonable expectations.
Now, if only it were weathersealed and f/2.8 for the winter.....
John
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