DVX auto focusing so slow!

S

shaun_au

Active member
I'm a new DVX user. But I found the auto focus is so slow. I was shooting a wedding. When the bride and groom exchange rings, the close up of their hands just can't get focused! All the audience in the background was sharp. I mean the hands were like in dead center of the image. The auto focus took like 30 seconds to get a grip on the hands. I can't believe this! Now I'm looking at this out of focus footage and very very disappointed. I don't know if there's anything I've done wrong or that's just the way DVX focuses.

Can anyone help?
 
You're in 24p or 24pa mode, right? Autofocus doesn't work at that framerate...so they call it focus assist. It still works, but not quickly enough to be useful in rapidly changing situations.

Dan
 
Were you, by chance, shooting 24p or 30p?

Autofocus requires three things in order to work well:
1) a fast framerate (autofocus works best in 60i)
2) enough light (all autofocus systems perform much worse in low light conditions)
3) enough contrast (autofocus needs to see some contrast to work well).

You're asking if there's anything you've done wrong -- I think the majority of responses you'll get here are "yes, what you did wrong was use autofocus". Autofocus has its place, but manual focus is much more reliable and precise, if you take the time to learn it and practice so you get good and quick with it.
 
Barry_Green said:
Were you, by chance, shooting 24p or 30p?

Autofocus requires three things in order to work well:
1) a fast framerate (autofocus works best in 60i)
2) enough light (all autofocus systems perform much worse in low light conditions)
3) enough contrast (autofocus needs to see some contrast to work well).

You're asking if there's anything you've done wrong -- I think the majority of responses you'll get here are "yes, what you did wrong was use autofocus". Autofocus has its place, but manual focus is much more reliable and precise, if you take the time to learn it and practice so you get good and quick with it.
Click to expand...

Yeah, I was in 24p mode. Damn, it's a hard lesson I learned. Oh well, will use manual focus for 24p from now on. Thanks for the hint, guys. Yeah, I've been using manual focus. I'm slowly getting used to it.

Another thing I noticed. If I'm at full telephoto, and have my subject in focus(close up), when I slowly pull back from full T as the subject walks towards me, I can still have him in focus. But if I go from full W to full T, it's much harder to keep the focus on him as he walks away and eventually have a sharp close up on him(shallow DOF).

Barry, do you have any articles on manual focusing in 24p?

Thanks.

Shaun
 
Starting telephoto and going wide is easy, because as you zoom out the range of depth of field grows deeper (meaning, even more and more of the shot comes into focus). Going the other way is much harder, because as you zoom in, less and less of the shot is in focus. You pretty much have to start out at full telephoto and grab your focus point there, then zoom out and start your shot.

No specific articles on manual focusing, but you can learn about depth of field in the DOF Tutorial thread. The more you know about depth of field and how to maximize it, the easier you'll find focusing to be.
 
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