I believe Tony was using a 5D iii. The extender on a 400mm f5.6 would lose autofocus on crop cameras and even on the 6D wouldn' t that combo result in an F8. Hard to believe that would be better than the Tamron at 600mm. Let's not forget that his review was favorable for both the Tamron and the Canon 400mm f5.6. Also keep in mind that the Canon 400 5.6 is over $1300 and the extender is about another $500 while the Tamron is $1069.

I agree. I also have the Canon 100-400 lens and used to have the Sigma 150-500. I prefer the Tamron although I use the 100 - 400 for handheld shots.
Bill

Do you lose autofocus? Does the lens hit up against the extender. I read that the Canon extender can damage the 70-300L lens. What brand extender are you using?
Bill

I have both of these lenses. I like them both but the 70-300 is not a replacement for the 100-400. What helped me was a sling strap. The 100-400 is much easier to carry with the sling and then I have the strength to hold the 100-400 when needed.
Bill

I am very happy with my 150-600 and I use it with my 7D with no problem.
Bill

If you could, would you buy this lens?[/quote]

I agree with Jim.
I just started using my 6D and I am amazed at how well it handles high ISOs with so little noise. Canon Direct is having a great sale on them. I bought mine as a refurb for $1291.32. New 6Ds are on sale too.
Bill

quote=oldtool2]Phil,

I debated about it and finally pulled the trigger, for the price I am not regretting it. For the money it is an amazing camera body! I can't believe how well it handles noise and high ISO's.

Jim D[/quote]

Lfingar
Thank you for your response. I saw your original post about the high ISOs several weeks ago and it was influential in my ordering the 6D. It looks like it will do much better than my 7D as far as noise is concerned.

Joe
Thank you for your answer. I have several Canon L lenses to use with the 6D and as well as the Tamron 150-600, so I have the full range covered. I was just curious about the use of the 1.4 teleconverter as I already own it.

I ordered a Canon 6D and am waiting for delivery. My question concerns the Canon 400mm f5.6 lens and 1.4 Canon teleconverter combination. Does anyone know if I will retain autofocus with that combination? And how well does it do in terms of sharpness and noise?

You might use the 150-400 range. I do. That is the advantage of the zoom over the prime. But if you have other lenses that cover that range then the 400 prime has the advantage based on sharpness.

See Tony Northrup's Utube video comparison of the Tamron 150-600 and the Canon 400mm 5.6 with 1.4 tele. He concluded that the 400 mm 5.6 tele combo was sharper. Of course you would need a full frame camera to retain autofocus. There are many fellow Hoggers who like the Sigma 150-500. I did not like it and I find the Tamron 150-600 to be superior. Yes, I was one of the lucky ones to buy the Tamron 150-600 early. I have been told that Sigma's quality control is inconsistent and I may have gotten one of the bad ones. I sold the Sigma and I'm happy with the Tamron.

I have both. I use the Fuji waterproof for the beach, the pool and kayaking. It's great for that but it's not good at red eye reduction for
indoors. My Canon 260 is fine as a pocket camera although it is larger than the smaller compacts. It has a nice 25x zoom and you can control aperture and shutter speed. No RAW though, only JPEG. Canon now has a 280. None of these pocket cameras replace my DSLR cameras but they come in handy when you don't want to carry anything big.
Bill.

Linda
I Checked out the link to your photos. They are great. I have the 50x and have just started to use it. I have not been happy with my results so far and was thinking of selling it. You have inspired me to keep it and learn to master it.

I agree with lfingar. I find I usually need at least 400mm for birds. I recommend the 100-400 but it sounds like that is not in your budget so then go for at least the 70-300.

I have the Tamron 150-600 and the Canon 100-400. I use both on my 7D and have not had a problem with autofocus.