It can be used at all focal lengths, because it offers a very good sharpness throughout. However, the quilted lack some teeth in the distant views or shorter distance. But overall, the performance and made me seem quite comparable to the objective "expert" Nikon (same characteristics and optical design very similar). I find it even better than the 300 mm Nikon 70-300mm F4.5-5.6G IF-ED AF-S VR.
The zoomings will be facilitated by the large ring that is very accesible and comfortable to maneuver. Autofocus is fast and very silent, clean finish well and the goal really inspires confidence.
The 70-300mm range is classic and bright enough for most uses. We can just regret lower focal (F2.8) for portraits that would have allowed beautiful "blurred" background.
The stabilizer and engine are discreet, as on the Nikon, but they can also cause a slight tremor noticeable image in the viewfinder during the development. Although nothing dramatic though.
The visual quality of the dive is still good throughout the focal range. I have found that some vignetting and chromatic aberrations. In contrast distortion, enough has from 70 to 105 mm, must be corrected in post-processing.
On paper, the value is really good. However, it will inevitably compare this model, particularly in case you want to resell the used thereafter, with the NIKON 70-300mm F4.5-5.6G IF-ED AF-S VR.
Have fun!
