Convertor or lens advice please.

I have the 5.6 400 L and really like this lens. But in some cases I have needed a little more reach. Also, some of the outings I want to go on I know I will need more. So this is where I need the advice. I currently can not afford a 500 or 600mm L series Canon.

I am torn between a 1.4 along with a 2X convertor or maybe a 150-500 sigma. I know a lot of the great photogs on here have tried both. So, any advice will be taken seriously.

It will mostly be used for birding and wildlife photography.


Thanks in advance guys and gals.

What camera body do you have? Obviously you will lose AF when you slap a TC on the 400 f5.6 if you don't have a 5d3 / 1d*...

I have the 7D. I should retain auto focus with the 1.4 but not the 2X

PeteD wrote in post #16037976
I have the 7D. I should retain auto focus with the 1.4 but not the 2X

With Canon TC, no you don't, as 1.4x TC makes it a f8 lens.

Only 5D3 and 1 series body can AF @ f8.

Third party TC such as Kenko works, but it's slow and tends to hunt.

I wouldn't bother with the 150-500 it will not offer you much more and is slower focusing than the 400 f5.6 and will be softer wide open. As has been said you will not get AF with either tc with your camera body (though it should AF if you use livevew with the 1.4x), and the image quality will take a bit of a hit. You might find that cropping a bit gives as good results as using a 1.4x, it would be interesting to test that. The 2x will definitey havea much bigger impact on IQ so you would be better off with the 1.4x if you do go for one of them.

One should always get, or rent for a week, a 1.4x TC before even thinking about a 2x TC. I have used both with the 400/5.6 on a monopod and gotten great results. Of course, I only use MF. Gene

Thanks everyone for the help soo far.


I have read on here and other forums that you do have auto focus with the 1.4. Looks like it may be one of those things where I will just have to give it a try just to find out.

I knew I would lose it for certain with the 2X.

So, you guys think I would still be better with the convertor over the Sigma?

PeteD wrote in post #16040053
Thanks everyone for the help soo far.


I have read on here and other forums that you do have auto focus with the 1.4. Looks like it may be one of those things where I will just have to give it a try just to find out.

I knew I would lose it for certain with the 2X.

So, you guys think I would still be better with the convertor over the Sigma?

the difference in reach between the 400mm, and the long end of the 150-500mm(which is supposed to be somewhere around 480mm) isn't enough to justify the change in my opinion...the sigma needs to be stopped down to f8 to get good center sharpness...and even then you're probably giving up better AF for it... one possible thought could be along the lines of the sigma 120-300mm f2.8 OS with TCs...although that's a lot more money

Unless you tape over 3 pins, you will indeed lose AF with a 1.4x.

PeteD wrote in post #16040053
I have read on here and other forums that you do have auto focus with the 1.4. Looks like it may be one of those things where I will just have to give it a try just to find out.

If you get something like the Kenko TC then yes your 7d will probably try and AF with the 1.4x extender... it won't be as quick as normal though. It's not supposed to focus, and a Canon-specific extender wouldn't work... only the 5d3/1d* bodies can AF on the centre point at f8 as mentioned above. Taping the pins as gasrocks mentioned is a way of tricking communication between the TC and the camera so the camera doesn't know the lens is now an f8 lens, hence it still tries to AF. I don't know what you've read elsewhere, but don't buy a 1.4x TC and expect it to operate as normal on your 7d...

Well, I got to borrow a 1.4 today to try out. I did have auto focus . Albeit it was in high noon lighting. Who knows with any other type. It was a little on the slow side but, did work

Havce read that the IQ is about the same between the 1.4 and the siggie so I may just save quite a bit and go with the convertor.