Is there a way to make auto-focus more smooth while filming with Sony A55?

Question

Wondering if anyone can help with this. I have a Sony SLT-A55, and when in video recording mode it is able to auto focus.

My issue is that it does this "too quickly".

For example, if I'm shooting something and I'm panning across, following a subject, if anything passes close in front of the camera for even a second it will try to focus on that, then will have to refocus on the subject I was following. This causes a really annoying focus-loss effect on the video. To give you more of an idea as to whats happening the following link shows an example. You will notice that it loses focus half way through. This can happen multiple times so it becomes really noticeable.

http://www.youtube.com/watch?v=6UwvjMiNwH8

So my question is, how can I prevent this, without having to go into full manual focus mode? From research I have found out that lenses are available with focus hold buttons — would getting a lens with this help? Would I have to hold the button down the entire time during which I don't want auto focus, or would it be a toggle style button?

Is there anyway I can prevent this? Slow the focus when the subject goes out of view? Buy some sort of better lens?

Answer 1

Focus hold buttons, from my understanding, just disengage the autofocus and 'hold' the focus where it currently is, not on a moving subject - so pressing this will not create a kind of 'follow focus even if you can't see the subject' scenario.

I don't think you're going to find any way around this, except for manual focusing- the camera literally can't see the subject when it passes it behind the object. You could use another camera with worse video autofocus like a Nikon D3100, D5100, etc but I have one, and the video autofocus is TERRIBLE. Its noisy, super slow, unpredictable - I'd not recommend it at all.