Had to try it: 280mm f/4 APO + 1.4x APO-Extender-R + 2x APO-Extender-R on the R8/DMR (on a big Gitzo braced against a 6" x 12" post) http://www.wildlightphoto.com/birds/picidae/melanerpes/lewood04.html Doug Herr Birdman of Sacramento http://www.wildlightphoto.com