[robski]

Hugh

I agree with the concept of getting closer to the subject. The D70 and 50-500 is a fairly good setup. But the 50-500 is not the best of lens.

If you stick it on a D2X the increased resolution will show up the lens more as the sensor will out resolve the lens. e.g you just end up with a bigger blured version of your shot on screen.

Putting a TC on it will make the image very dark so the camera will struggle to Auto focus or hard to see if you manual focus. May be OK in bright light.

When using a TC you really need a good wide aperture prime lens to get the best results. Like a 500mm f4.

The problem with 800mm lens is that haze ( heat, pollen, mist ) becomes a problem with long distance work at certain times of year.