D30 +1.4 Extender +100-400mm = Won't Autofocus

[gthorn]

Has anyone else tried a D30 + 1.4x Extender II + 100-400mmIS lens combination ? I have this and the camera won't autofocus at all and I can't find any information that says it should or shouldn't.

I'm no expert at these things, but I can't understand why the camera won't autofocus. Any opinios will be appreciated.

Graham Horn

[vvizard]

What aperture is that lens? You'll loose one fstop from the 1.4x converter I think. That means that if your lens is a f/4, it will act as a f/5.6 with the 1.4x converter. f/5.6 is also the "slowest" the cam can autofocus, so if the aperture of the lens is slower than f/4 it's very normal that it won't autofocus.

Correct me if I'm wrong about the numbers now.

There is though a trick I've read, to tape over three of the pins on the converter, but I don't own the converter myself, and don't know if it actually works (or is safe for that matter).

[RichardtheSane]

The 100-400 is F4.5-5.6, so the problem is because with the 1.4x a convertor it is making it an effective F8, which is too slow to autofocus on the D30.

A Viz said, do a search for information about taping the contacts, and you should get AF, even though it may not perform as well as without the convertor. :D

[defordphoto]

I have that combo (rarely use it as the 1.4 is really for the 70-200) and the lens acts freaking weird with the contacts taped. I wouldn't suggest it.

[chris maddock]

RFMSports wrote:
I have that combo (rarely use it as the 1.4 is really for the 70-200) and the lens acts freaking weird with the contacts taped. I wouldn't suggest it.

Yeah, it's not brilliant with the D30 - needs good light and a contrasty area of the subject to have much success.

It works great on the 10D though in all but poor light IME - one of my main reasons for getting the 10D was the AF improvement.

KRs
Chris

[defordphoto]

It's definitely a daylight lens, but surprisingly high-rated for being one of the cheaper, long L's. I have the 70-200 for low-light stuff.