I'm looking for a 400mm and am tempted by these old trombones. Both seem to suffer from less purple fringing than non-apo telephoto designs, are long, but light and fall within budget. I know both have slight curvature issues at the edges, but are supposedly centrally decent - should be fine for wildlife etc. There are plenty of impressive shots with the Leica but samples of the Novoflex's output seem harder to track down. The Telyt seems to go for about 3x the price of the Novoflex, but is that more about the branding or is it significantly better? There's about 1/2 a stop extra on the Novoflex... Any experiences?