400mm lens or 200mm and doubler?

[Gints Klimanis]

Don't be so down on teleextenders. While "doublers" or 2x teleconverters from Nikon (can't speak for Canon) soften the image considerably, you have to compare that damage to what you would otherwise achieve with cropping. Given today's higher resolution cameras (12+ MP), I'm getting the feeling that 2x teleconverters are easily exceeded by cropping. This is partly due to avoiding the softening due to the converter itself, but also due to a higher shutter speed/lower ISO and less lens vibration due to the shorter effective focal length. Also, accurate auto-focusing is compromised because the teleconverters cut down the effective aperture.

I am quite happy with the results of my Nikon TC14 and TC17 teleconverters on a 400mm f/2.8 lens. It takes quite a bit of practice to shoot at the longer focal lengths, but starting with a "faster", sharper lens helps. My results on a zoom lens such as the stellar Nikon 70-200mm VR were less than satisfactory at 200mm, but just fine on the 200mm VR f/2.