Focus pulse at DVinfo.net

Chuck Fadely · January 27th, 2007, 10:13 AM

Ok, I read earlier threads on focus pulsing and thought they were wacko.

But I had it happen to me this week. I was shooting a long shot of boats at infinity, ois on, probably af on, not zooming. First couple seconds of this one shot are fine, then it goes into a rapid (i'm guessing, but maybe 4x per second) in-and-out of focus pulsing. Much faster than the af works.

I was shooting similar shots all day, both before and after, and it only happened for this one shot, and not for the whole shot.

Anyone else have this happen? I'm wondering if it could be rf inteference from a cell phone or a motor?

Philip Williams · January 27th, 2007, 11:52 AM

You didn't mention your shooting mode. Was it 24F?

Chuck Fadely · January 27th, 2007, 04:33 PM

It was 1080i60 when it happened.

Khoi Pham · January 27th, 2007, 04:56 PM

Quote:

Originally Posted by Chuck Fadely

It was 1080i60 when it happened.

This is just the way Canon camera focus behave, it is not very good, you just have to accept it or learn how to use manual focus, what happen is that it couldn't decide what to focus on, it might lock onto something but then it see something else with more contrast and switch to it or you are right on the edge of the focusing area and it switch back and forth, or it could be that you have the IF on at the same time as auto focus, the IF beam might hit on something in the foreground but the auto focus (base on contrast and vertical lines) might see something else in the background and the system couldn't decide what to focus on and so it hunt. The best is to learn to manual focus, if not then I would turn off the IF and use only auto, and use push button AF when needed.

Gabriel Yeager · January 27th, 2007, 05:06 PM

Hi Chuck, I have had this same thing happen to me. I believe it is just the Auto Focus trying to chose the subject. Much like what Khoi said. I would recommend using manual focus anyways.

Best of luck!
~Gabriel

Dave Halliday · January 27th, 2007, 06:08 PM

i had this happen to me this week--but I had my A1 on manual focus. It has some weird pulsing issues. Fairly minor, and it's at the edge of the frame. I'm shooting at 60i. I don't think it's in every shot--don't know yet. I haven't tested it too thoroughly.

Chuck Fadely · January 28th, 2007, 12:09 AM

It seems much too rapid to be af hunting. It's very unlike any af issue I've seen before.

Chris Hurd · January 28th, 2007, 12:47 AM

Is this happening when the Instant AF feature is on? If so, that could account for the rapid hunting.

Dave Halliday · January 28th, 2007, 09:19 AM

For me, no. I'll post a short clip as soon as i get back in my editing room. no af, no iaf.

Philip Williams · January 28th, 2007, 01:37 PM

I seem to recall that I was able to create the effect with IAF on and off. Now I definitely have not been able to create the pulsing with AF completely off.

January 27th, 2007, 10:13 AM	#1
Chuck Fadely Major Player Join Date: Jul 2006 Location: United States Posts: 306	Focus pulse Ok, I read earlier threads on focus pulsing and thought they were wacko. But I had it happen to me this week. I was shooting a long shot of boats at infinity, ois on, probably af on, not zooming. First couple seconds of this one shot are fine, then it goes into a rapid (i'm guessing, but maybe 4x per second) in-and-out of focus pulsing. Much faster than the af works. I was shooting similar shots all day, both before and after, and it only happened for this one shot, and not for the whole shot. Anyone else have this happen? I'm wondering if it could be rf inteference from a cell phone or a motor?

January 27th, 2007, 11:52 AM	#2
Philip Williams Major Player Join Date: Aug 2004 Location: Snellville, Georgia Posts: 614	You didn't mention your shooting mode. Was it 24F? __________________ www.philipwilliams.com

January 27th, 2007, 05:06 PM	#5
Gabriel Yeager Major Player Join Date: Jul 2006 Location: Washington, NorthWest USA Posts: 788	Hi Chuck, I have had this same thing happen to me. I believe it is just the Auto Focus trying to chose the subject. Much like what Khoi said. I would recommend using manual focus anyways. Best of luck! ~Gabriel __________________ Gabriel Photography

January 28th, 2007, 12:47 AM	#8
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,369 Images: 513	Is this happening when the Instant AF feature is on? If so, that could account for the rapid hunting. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

January 28th, 2007, 01:37 PM	#10
Philip Williams Major Player Join Date: Aug 2004 Location: Snellville, Georgia Posts: 614	I seem to recall that I was able to create the effect with IAF on and off. Now I definitely have not been able to create the pulsing with AF completely off. __________________ www.philipwilliams.com

January 27th, 2007, 04:33 PM	#3
Chuck Fadely Major Player Join Date: Jul 2006 Location: United States Posts: 306	It was 1080i60 when it happened.

January 27th, 2007, 06:08 PM	#6
Dave Halliday Regular Crew Join Date: Feb 2006 Location: Washington DC Posts: 116	i had this happen to me this week--but I had my A1 on manual focus. It has some weird pulsing issues. Fairly minor, and it's at the edge of the frame. I'm shooting at 60i. I don't think it's in every shot--don't know yet. I haven't tested it too thoroughly.

January 28th, 2007, 12:09 AM	#7
Chuck Fadely Major Player Join Date: Jul 2006 Location: United States Posts: 306	It seems much too rapid to be af hunting. It's very unlike any af issue I've seen before.

January 28th, 2007, 09:19 AM	#9
Dave Halliday Regular Crew Join Date: Feb 2006 Location: Washington DC Posts: 116	For me, no. I'll post a short clip as soon as i get back in my editing room. no af, no iaf.