Auto Focus does not work

[Allen Birnbach]

I have rented a DVX100P camera. The auto focus does not seem to work when the focus switch is set to A, nor does the Push Auto active auto focus when the focus switch is in Manual. In both cases, I get an on screen prompt saying "MF only." I've checked the Auto SW settings in the menu, and everything is off there. Any suggestions of what may be happening would be appreciated.

 

[Barry_Green]

The original DVX100 could not use autofocus when in 24P or 30P mode, only in 60i mode.

 

[Allen Birnbach]

Thanks. At least I know it's not me.

 

[Allen Birnbach]

By the way, which models would auto focus in 24P? It would be good to know when I make a rental reservation next time.

 

[Barry_Green]

100A and 100B. But, autofocus performance in 24P is very slow, which is why they disabled it in the first place. Autofocus requires frequent updates to perform well, and you only get those frequent updates when shooting 60i.

 

[Allen Birnbach]

Thanks. Good information to have. I'm curious as to why shooting the different format changes the focusing ability. If you don't mind, I'd like to understand that better. I'm going to have to buy a camera soon, so understanding the advantages/disadvantages of the different models would be helpful.

 

[Barry_Green]

At 60i, the autofocus system gets fed sixty updates per second. At 24P, it only gets fed 24 updates per second. The ability to react quickly is obviously much better when you're getting two and a half times more frequent feedback. So the autofocus is dramatically more responsive in 60i than it is in 24P or 30P. Accordingly, Panasonic disabled autofocus on the 24P and 30P because they figured it'd be too slow to actually be of much use and they'd just get complaints.

People complained anyway, saying 'hey, we want it, let us have it." So in the 100A they enabled it, but they didn't call it "autofocus", they called it "focus assist." People now complain about how slow it is (duh!)