150-450mm focus adjust

NeilP · 2016-07-17T21:25:56+0100

Ive been finding my 150-450mm a bit soft at 450mm f5.6. So I took a couple of shots of a chart (which I had to colour in the focus point with black pen), focusing with liveview on, using back button focus and 2sec delay while mounted on a tripod. The chart was roughly 45 degrees to the lens. Im not 100% sure but it looks like its focusing OK perhaps slightly front focusing? Question is, is this enough to account for the loss of sharpness shown in the thread below or is this lens faulty? https://www.pentaxuser.com/forum/topic/is-the-150-450mm-sharp-at-450mm-wide-open--56332