Focus hunting on Auto Mode at DVinfo.net

Roy Kerwood · September 26th, 2003, 11:20 AM

I set-up my camera on a tripod in my office on auto mode in HD and I noticed that the focus keeps shifting even though The subject, me, does not move significantly, has anyone else noticed this? I will post a clip from the video tonight..

Steve Mullen · September 26th, 2003, 11:23 AM

That's why after letting thecamera AF -- you turn-off AF.

Dave Largent · September 27th, 2003, 05:32 AM

Roy, where will you be posting the clip?
And Steve, does it shift like that in all lighting conditions or just if it's in low light?

Steve Mullen · September 27th, 2003, 12:01 PM

AF uses scene contrast -- usually in the center of the frame.

Small changes in objects or lighting cause it to re-evaluate the focus. Hence hunting. This tends to hppen more in low light.

I don't think it's a good idea to leave AF on once you have got your focus.

Eric Bilodeau · September 27th, 2003, 02:06 PM

Steve's got a point here. I totally agree, if ever you want to use AF, on a still shot that is, once it is done, de-activate it.

September 26th, 2003, 11:20 AM	#1
Roy Kerwood Tourist Join Date: Sep 2003 Location: Vancouver Posts: 4	Focus hunting on Auto Mode I set-up my camera on a tripod in my office on auto mode in HD and I noticed that the focus keeps shifting even though The subject, me, does not move significantly, has anyone else noticed this? I will post a clip from the video tonight.. __________________ Roy Kerwood

September 26th, 2003, 11:23 AM	#2
Steve Mullen HDV Cinema Join Date: Feb 2003 Location: Las Vegas Posts: 4,007	That's why after letting thecamera AF -- you turn-off AF. __________________ Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c

September 27th, 2003, 12:01 PM	#4
Steve Mullen HDV Cinema Join Date: Feb 2003 Location: Las Vegas Posts: 4,007	AF uses scene contrast -- usually in the center of the frame. Small changes in objects or lighting cause it to re-evaluate the focus. Hence hunting. This tends to hppen more in low light. I don't think it's a good idea to leave AF on once you have got your focus. __________________ Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c

September 27th, 2003, 02:06 PM	#5
Eric Bilodeau Major Player Join Date: Jun 2003 Location: Chicoutimi, Canada Posts: 334	Steve's got a point here. I totally agree, if ever you want to use AF, on a still shot that is, once it is done, de-activate it. __________________ Eric Bilodeau video SFX,DOP ___________________ http://www.fictis.net info@fictis.net

September 27th, 2003, 05:32 AM	#3
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Roy, where will you be posting the clip? And Steve, does it shift like that in all lighting conditions or just if it's in low light?