HV30 on IAF drifts out of focus. at DVinfo.net

Jonathan Levin · April 7th, 2009, 09:58 AM

Greetings.

My HV30 set to IAF mounted on tripod with Image stabilizer off, tends to drift in and out of focus briefly. This may happen after three or four minutes, and then may not happen again for another few minutes.

Subject matter is a seated person and there is a little movement so I'm guessing that the IAF is catching that.

My solution has been to use manual focus which I always prefer, but I wonder why this is happening and if anyone else has had this problem? Would using Non-instant auto focus be a better choice in situations where you need to use auto focus?

Is there a focus lock on the HV30, or is that just manual mode?

Thanks.

Jonathan

Tripp Woelfel · April 7th, 2009, 07:19 PM

I use an HV30 as a locked off B cam for interviews. Since it's off to the side, I generally don't have to worry about the subject moving in and out of focus. As such, I can manually set the iris and focus to get a decent DOF. You can see how it works here: Ben Ashline - Profile of a Young Racer on Vimeo I set up the HV30 up so I got a little softness off the far wall.

Moral of the story is to set your focus manually for locked off shots.

Dave Blackhurst · April 7th, 2009, 09:59 PM

it may have to do with the "focus point" - if the subject moves a bit off what the camera decides is "center", it may try to focus on a new plane. "Auto" is only as smart as the algorithm - and typically they center weight the focus in a fairly small area of the frame. If your subject is off center... or in and out of the sweet spot, you could see drift, especially if you've set the camera up to try to get shallow DoF.

Jonathan Levin · April 8th, 2009, 09:29 AM

Thanks fellows.

April 7th, 2009, 09:58 AM	#1
Jonathan Levin Major Player Join Date: Apr 2008 Location: Chicago, Illinois USA Posts: 692	HV30 on IAF drifts out of focus. Greetings. My HV30 set to IAF mounted on tripod with Image stabilizer off, tends to drift in and out of focus briefly. This may happen after three or four minutes, and then may not happen again for another few minutes. Subject matter is a seated person and there is a little movement so I'm guessing that the IAF is catching that. My solution has been to use manual focus which I always prefer, but I wonder why this is happening and if anyone else has had this problem? Would using Non-instant auto focus be a better choice in situations where you need to use auto focus? Is there a focus lock on the HV30, or is that just manual mode? Thanks. Jonathan

April 7th, 2009, 07:19 PM	#2
Tripp Woelfel Trustee Join Date: Jan 2008 Location: North Conway, NH Posts: 1,745	I use an HV30 as a locked off B cam for interviews. Since it's off to the side, I generally don't have to worry about the subject moving in and out of focus. As such, I can manually set the iris and focus to get a decent DOF. You can see how it works here: Ben Ashline - Profile of a Young Racer on Vimeo I set up the HV30 up so I got a little softness off the far wall. Moral of the story is to set your focus manually for locked off shots.

April 7th, 2009, 09:59 PM	#3
Dave Blackhurst Inner Circle Join Date: Feb 2007 Location: Apple Valley CA Posts: 4,874	it may have to do with the "focus point" - if the subject moves a bit off what the camera decides is "center", it may try to focus on a new plane. "Auto" is only as smart as the algorithm - and typically they center weight the focus in a fairly small area of the frame. If your subject is off center... or in and out of the sweet spot, you could see drift, especially if you've set the camera up to try to get shallow DoF.

April 8th, 2009, 09:29 AM	#4
Jonathan Levin Major Player Join Date: Apr 2008 Location: Chicago, Illinois USA Posts: 692	Thanks fellows.