Canon 2x Extender

One of the problems of bird photography is having a lens long enough to get a nice close up of your subject without having to approach too close.
The obvious option is a telephoto lens, but once you get to a certain level these go from being expensive to being very expensive!
The lens I currently use is a Cannon 300mm f4 L, more often than not I pair this up with a 1.4x extender to give a 420mm f5.6. However on occasion I would like more reach (especially doing hide photography on nature reserves).
So for that reason I thought I would chance a 2x extender to give me a 600mm f8 lens. I have been in the garden today 'playing' with this combination and I have to say I am pleasantly surprised by the results; From reading various reviews I was expecting most of the images to be soft but in all honesty they are coming out reasonably sharp and respond well to post processing.
On non 1 series Canon bodies autofocus won't work unless the maximum aperture is f5.6 or less, so as the 2x extender makes the f4 lens an f8 AF doesn't work, unless you use live view and rely on the 'live' AF. Although it's not the quickest it did prove itself to be accurate.
The images below were taken today, the lens was mounted on a tripod and the shutter was fired using a remote release.



This is a 100% crop from the above image with no sharpening applied.



I am very pleased with this combination and the 2x extender is something I will definitely be using in the future.