The official test, though not scientific a test just the same. Shutter 1/250 f/5.6 on both setups. Cloudy conditions so both shots are close to the same lighting conditions. 70-200 @ 200mm http://www.gaengineer.com/200WOtele.jpg 70-200 @ 100mm with Tele http://www.gaengineer.com/100Wtele.jpg Notice the color loss on 100WTele.jpg. I think I am going to return the Tele Converter. The sharpness fall of is acceptable, but the color loss isn't for me. I think I will save up for the Bigma 50-500 Sigma lens or Nikkor 80-400VR.