Keeping focus over long distances at DVinfo.net

Al Ioimo · December 6th, 2006, 06:58 AM

Hello, I own a Sony PD170 I use to tape weddings. This problem has occurred a few times so I thought I would post a message. When filming a weddings I can’t seem to keep everything in focus, running some tests before the ceremony My son is on the alter and I at the back of the church,(about 200 ft) I have him zoom in on me and focus manually using the focus ring if needed because of the low light and the distance between him and I the auto focus button does not always work. Then I have him pan back as I walk down the ial to get in position as if I where the bride (about 6 ft). When I get to the alter I am out of focus. How can I film the whole ceremony and keep every thing in focus? Would the infinity control on my camera be the answer?

Thanks for any help.

Al Ioimo

Mike Rehmus · December 6th, 2006, 08:43 AM

You are experiencing normal operation, there is no good solution on a PD170 because it doesn't have a calibrated focus on the lens. On a 'real' manual lens you can continuously alter the focus just by adjusting as the bride travels the aisle. You can also do this with the help of a scale on the lens or by placing mechanical stops that represent correct focus at the distant and close-up positions (although that normally requires a second person to operate the lens).

You can practice slowly turning the 170's focus ring to keep the bride in focus during her trip down and up the isle. Fortunately they always walk relatively slowly.

In dim light, you've already found out that autofocus is useless. Infinity isn't the answer because the scene will be out of focus with the lens wide open.

This is why they have multiple people operating a single camera when they make a movie.

Al Ioimo · December 8th, 2006, 06:21 AM

Thanks Mike for the advice.

John Laird · December 8th, 2006, 02:29 PM

This is a tough one. I shoot weddings too and have run into several situations where auto focus failed to lock properly during a processional, and even when there was good lighting! I always shoot processionals in manual focus and keep my finger hovering above the push auto button. As they come down the aisle every 10 feet or so I push auto for a second or two to keep focus. This keeps the focus from actively hunting or pulsing. It also allows me to instantly disengage it if it does screw up and I can manually compensate, reframe and maybe try again.

I've found that in addition to bright and/or shiny things (the bane of Sony auto focus users everywhere), the PD170's auto focus prefers stationary large objects in the center of the frame. If things are moving through the frame, it usually won't try to lock in on them. Keep your subjects framed large and center and track them well and you should be okay.

Excessive detail at a distance behind subjects can cause problems too in stationary shots. The camera will always try to resolve as much detail as it can and sometimes that detail isn't in the same focal plane as your subjects :( Beware of brightly lit detailed backgrounds and dimly lit subjects! This is common in a number of churches. Not much you can do there except be aware of the issue ahead of time and tweak the focus ring as needed. Manual focus combined with occasional use of the push auto button is the key to the best shooting you can do.

John

December 6th, 2006, 06:58 AM	#1
Al Ioimo New Boot Join Date: Dec 2004 Location: Chino Hills Ca Posts: 19	Keeping focus over long distances Hello, I own a Sony PD170 I use to tape weddings. This problem has occurred a few times so I thought I would post a message. When filming a weddings I can’t seem to keep everything in focus, running some tests before the ceremony My son is on the alter and I at the back of the church,(about 200 ft) I have him zoom in on me and focus manually using the focus ring if needed because of the low light and the distance between him and I the auto focus button does not always work. Then I have him pan back as I walk down the ial to get in position as if I where the bride (about 6 ft). When I get to the alter I am out of focus. How can I film the whole ceremony and keep every thing in focus? Would the infinity control on my camera be the answer? Thanks for any help. Al Ioimo

December 6th, 2006, 08:43 AM	#2
Mike Rehmus Wrangler Join Date: May 2002 Location: Vallejo, California Posts: 4,049	You are experiencing normal operation, there is no good solution on a PD170 because it doesn't have a calibrated focus on the lens. On a 'real' manual lens you can continuously alter the focus just by adjusting as the bride travels the aisle. You can also do this with the help of a scale on the lens or by placing mechanical stops that represent correct focus at the distant and close-up positions (although that normally requires a second person to operate the lens). You can practice slowly turning the 170's focus ring to keep the bride in focus during her trip down and up the isle. Fortunately they always walk relatively slowly. In dim light, you've already found out that autofocus is useless. Infinity isn't the answer because the scene will be out of focus with the lens wide open. This is why they have multiple people operating a single camera when they make a movie. __________________ Mike Rehmus Hey, I can see the carrot at the end of the tunnel!

December 8th, 2006, 06:21 AM	#3
Al Ioimo New Boot Join Date: Dec 2004 Location: Chino Hills Ca Posts: 19	Thanks Mike for the advice.

December 8th, 2006, 02:29 PM	#4
John Laird Regular Crew Join Date: Feb 2004 Location: Waterloo, IA Posts: 32	This is a tough one. I shoot weddings too and have run into several situations where auto focus failed to lock properly during a processional, and even when there was good lighting! I always shoot processionals in manual focus and keep my finger hovering above the push auto button. As they come down the aisle every 10 feet or so I push auto for a second or two to keep focus. This keeps the focus from actively hunting or pulsing. It also allows me to instantly disengage it if it does screw up and I can manually compensate, reframe and maybe try again. I've found that in addition to bright and/or shiny things (the bane of Sony auto focus users everywhere), the PD170's auto focus prefers stationary large objects in the center of the frame. If things are moving through the frame, it usually won't try to lock in on them. Keep your subjects framed large and center and track them well and you should be okay. Excessive detail at a distance behind subjects can cause problems too in stationary shots. The camera will always try to resolve as much detail as it can and sometimes that detail isn't in the same focal plane as your subjects :( Beware of brightly lit detailed backgrounds and dimly lit subjects! This is common in a number of churches. Not much you can do there except be aware of the issue ahead of time and tweak the focus ring as needed. Manual focus combined with occasional use of the push auto button is the key to the best shooting you can do. John