f8 AF question or the 7D and 1D4

[Richard8971]

I have the 7D and a Tamron 1.4 teleconverter. The 7D handles the teleconverter pretty well and if I find it wants to hunt (usually at 300mm on my 70-300L IS USM) and all I usually have to do is back off a little and I can lock AF pretty quickly.

I have tried to search but I can't find much info if the 1D4 will AF at f8. I know its an superior camera to the 7D but it's also the same age as the 7D. I was told it has a much better AF system than the 7D which is one reason why I am considering upgrading to it. I cannot afford the 1DX and the images from the 1D4 are superior to the 7D. I don't want a 5D3 and if I ever do decide to get another FF camera I will invest in a good used 5D2 or a new 6D. I don't need speed for the FF shooting I want to do.

Thoughts? Anyone use a Tamron 1.4x on f4 (or higher) glass on the 1D4?

Thanks in advance.

D

 

[Valvebounce]

Hi Richard.
I think I heard that some of the 3rd party extenders do not report aperture properly to the body so fooling the body in to believing it is focusing at an aperture that it can deal with. Unless it has been upgraded in firmware and I missed it I believe the 7D is not supposed to work at f8.
I'm sure someone will put me right if I'm mistaken. ;D
I'm sure sometimes my imagination works these things out and then tricks my brain in to thinking it is a fact! ???

Cheers, Graham.

 

[Deleted member 91053]

It would appear that your extender is of the non-reporting type as it should not work with that lens and the 7D which will not AF below F5.6.
The 1D Mk4 is designed to AF at F8. The AF will slow down quite a bit but I found mine accurate with a Canon 2 x extender on 300 and 600mm F4 lenses.

 

[Steve]

Yeah, it'll work with the TC on the 1DIV. Like john said, it'll slow down the AF a bit but it will perform better than it does currently on the 7D, guaranteed. Ideally, you should also look into upgrading your lens if you need more reach. There's the Tammy 150-600 and Sigma just announced a version today as well for the budget-limited in need of reach.

You should definitely make the body upgrade if you can, imo, because the 1DIV is the second best action camera available for EOS currently. That may change with the 7DII announcement, depending on its actual specs/price though, so maybe wait a couple days for that announcement.

 

[Richard8971]

Unless it has been upgraded in firmware and I missed it I believe the 7D is not supposed to work at f8.

No, you are quite correct, the 7D is not designed to AF at f8. However, that being said, it DOES AF with the Tamron 1.4x teleconverter 95% of the time. If I keep it just under 300mm it will usually lock on pretty quickly. It's not 100% but when the lighting is good I like to use it.

The 1.4x works much, much better on my 70-300L with my 7D than it does on my 40D. I was mainly curious if the 1DIV can AF at f8 using the same 1.4x tele and my 70-300L.

D