Which 1.4x TC to pair with the 100-400 MkII

I'm curious how the 100-400 II & 1.4xIII works for fast moving subjects, in terms of AF performance.

I rented the 100-400 II for an air show that I used with my 1D4. What a fantastic combo, with IQ approaching my Canon 300 f2.8 IS II.
But I didn't use my 1.4xIII, now I wish I had.

I have them both but have not used them yet.
From what I have read, adding the 1.4X slows down the autofocus enough to make it marginal at best for birds in flight.
Tripod mounted reports are very good.
For airshows probably OK?

Tapeman wrote in post #17888306
I have them both but have not used them yet.
From what I have read, adding the 1.4X slows down the autofocus enough to make it marginal at best for birds in flight.
Tripod mounted reports are very good.
For airshows probably OK?

Since you have both the EF 1.4x II and EF 1.4x III you would be the best one to tell us how they compare.

Perfectly Frank wrote in post #17888304
I'm curious how the 100-400 II & 1.4xIII works for fast moving subjects, in terms of AF performance.

I rented the 100-400 II for an air show that I used with my 1D4. What a fantastic combo, with IQ approaching my Canon 300 f2.8 IS II.
But I didn't use my 1.4xIII, now I wish I had.

Not sure, but the TC might be OK for planes. For birds in flight, I find that AF is too slow with the TC on the 100-400II.

I see little difference between the two extenders. I use the MKIII mostly on my 500 as it supposed to pair better with MKII lenses and used the MKII as a back up or on my 70-200 when in the field. I now own a 100-400 II so the MKII extender gets little use.

Even though I seldom did it I miss the fact that the MKII extenders could be used together as I did when I had my 300 f/2.8L IS.(1.4X & 2X)

Anyway optically and autofocus speed seems identical to me on the 1.4Xs. I did however see quite a difference between the MKII & MKIII 2X converters.

Down the road some of Canon's new lenses may benefit from the MKIII version.

Tapeman wrote in post #17888471
I see little difference between the two extenders. I use the MKIII mostly on my 500 as it supposed to pair better with MKII lenses and used the MKII as a back up or on my 70-200 when in the field. I now own a 100-400 II so the MKII extender gets little use.

Even though I seldom did it I miss the fact that the MKII extenders could be used together as I did when I had my 300 f/2.8L IS.(1.4X & 2X)

Anyway optically and autofocus speed seems identical to me on the 1.4Xs. I did however see quite a difference between the MKII & MKIII 2X converters.

Down the road some of Canon's new lenses may benefit from the MKIII version.

With addition of a 12mm ext tube between them you can stack any version TCs.

^^^^^

Don't you lose "infinity"?

Now that I don't have a 300 f/2.8L IS, I won't be wanting to stack extenders as my fastest telephoto is f/4.

Get the iii, and know you have the best, or get the ii and blame it for every off shot you take. Seems simple to me!

Tapeman wrote in post #17889199
^^^^^

Don't you lose "infinity"?

Now that I don't have a 300 f/2.8L IS, I won't be wanting to stack extenders as my fastest telephoto is f/4.

No loss of infinity when tube placed between TCs.