Thanks Rick - It's a big step up from the 800, and I'm pleased to notice that the colour rendition with the extra H-alpha in daytime seems perfectly adequate for a non-professional, despite Nikon warning that it was unsuitable for daytime photography. Here's some random pictures of birds at 400mm fl with it... https://www.flickr.com/photos/photon...57655058572216
cheers,
Andrew.