Thanks for the feedback. It was a difficultish shot to capture as the sun was not in the best of positions,hence it is slightly backlit. I was using a Canon 400D,as my 20D requires a new shutter. I was using shutter priority at1/1000sec,with an aperture value of F5 at ISO100. I was expecting them and have some nice shots of their approach,however they were closing at over 500kts and at only 3.5fps I was selecting my shots rather than attempting to machine gun them! I will re-edit and try adjusting the contrast and use some selective sharpening as I believe it is a softness issue in places rather than blur,although there was a fair amount of blur/haze produced from the jet efflux of both aircraft. It was one of those truly once in a lifetime experiences and I have only seen such speed at low level on a handful of ocasions,I was dumbstruck for a few minutes afterwards. The image was captured at 176mm and is more or less full frame,they were too close at 70mm as they passed me!!