Originally Posted by
rpcrowe
If you are shooting with 1.6x cameras a 2x extender will cost you two stops and you will lose your autofocus ability when using the 70-200mm f/4L IS. The 1D (series) Canon cameras will autofocus with a lens that has f/8 as its maximum aperture. I don't know about the 5D and 5Dii.
In my opinion, Canon dropped the ball big-time when they did not incorporate autofocus at f/8 in the 7D camera. That way, I could use the 1.4x TC on my 400mm f/5.6L and retain autofocus. Oh well, Canon tends to drop balls. They did it when they introduced the 270EX as a replacement for the 220EX. This little flash would have been great as a slave. They realized their error and introduced the 270EX ii which does have slave capability. However as an owner of the 270EX, that doesn't help me a hill of beans. Maybe we will see a 7Dii or an 8D with AF capability at f/8. Nice but, it won't help present 7D owners.
I have used a borrowed 2x extender once on the F4L and I didn't like the results. I lost my AF and the IQ was deteriorated beyond what I consider acceptable for an L lens.
I have heard very good things about the combination of the latest 2x TC and the 70-200mm f/2.8L IS ii lens. But that is an entirely different and very costly setup.
However, I have used the Mark-I 1.4x TC on my old non IS 70-200mm f/4L and it did fine. I presently occasionally use it on my 70-200mm f/4L IS model and although I can notice a very slight slowing of auto focus; the AF and IQ is still quite acceptable. I will often carry the 1.4x TC on trips JUST IN CASE I NEED A BIT LONGER FOCAL LENGTH. My standard travel kit is the 70-200mm f/4L IS and the 17-55mm f/2.8 IS on a pair of 1.6x cameras plus the 1.4X TC.
To tell you the truth, I haven't used the 1.4x TC on my 70-200mm f/4L IS in quite a while. However, I do use it fairly often on my 300mm f/4L IS lens and it does quite well with no GREAT slowing of AF or deterioration of IQ. There is still a bit of both but, the results are quite acceptable.
I have an older Hoya multicoated filter and the older ones seemed a bit more difficult to clean. I have heard that they have changed the coating to address that problem but, I have no experience with newer models. Most of my filters are B&W except for a Calumet CPL which I was told by a friend who works at Calumet was outsourced to B&W. The Hoya I own is good enough that I have no plans to replace it.
Have fun with your 70-200mm f/4L. It is a great lens.