EF Extender 2x III teleconverter

[Gila_Monster]

I am considering getting the Canon EF Extender 2x III to use with my Canon EF 100-400mm f/4.5-5.6 L IS USM lens.  I can't afford the Canon 800mm L lens, so I am thinking of the teleconverter.  In reading reviews I have seen some that say it is very sharp and others that say it is not.  What experience have forum members had?

[Nick_Prime]

I recently purchased the 100-400 and already had the 2xIII.  My first impression was, wow, what a handfull!  I am using a T3i and so far, other than not seeing the AF register lights or hearing the sound associated eith it being in focus, I am pleased after 2 weeks of use.

[stubby]

I also have the 100-400L and the 2xIII. I rarely use that combination when shooting with the 5dIII as you are very limited on apperature. I don't know which body you are using, but you will be at f/9 when shooting at 400mm on the lens, so you will need good light and a rather fast shutter to have decent photos.

As for photo quality, you will lose some IQ when using the 2x TC. You can still have sharp photos, but I guess it depends upon your skills, available light and shutter speed. Also remember that you will lose autofocus with this combination.

What are you intending to shoot with this setup?

[Gila_Monster]

Thanks for the replies.  I am using a 1Ds Mark III.  I want to shoot wildlife, especially birds.