How do I get better Autofocus?

Started Nov 15, 2012 | Discussions
saywhathomie
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How do I get better Autofocus?
Nov 15, 2012

I just got a 14mm Panasonic lens for my GH2. However, I'm quite new to this and wanted to learn how to get more continuous/steady autofocus.

My videos have a lot of a movement away and towards the camera. I shoot review videos and have to bring the product close up and set it back down again. Trouble is, the camera keeps focusing on a small bit of the video instead of the whole scope (Like my old camcorder does). This results in the video constantly focusing/refocusing whenever I move my hands and it looks terrible. Sometimes it doesn't focus at all!

Is there any way to configure the autofocus to perform better? Any settings in the GH2 or techniques?

Thank you for reading.

Panasonic Lumix DMC-GH2
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tedolf
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Don't use it.
In reply to saywhathomie, Nov 15, 2012

saywhathomie wrote:

I just got a 14mm Panasonic lens for my GH2. However, I'm quite new to this and wanted to learn how to get more continuous/steady autofocus.

My videos have a lot of a movement away and towards the camera. I shoot review videos and have to bring the product close up and set it back down again. Trouble is, the camera keeps focusing on a small bit of the video instead of the whole scope (Like my old camcorder does). This results in the video constantly focusing/refocusing whenever I move my hands and it looks terrible. Sometimes it doesn't focus at all!

Is there any way to configure the autofocus to perform better? Any settings in the GH2 or techniques?

Thank you for reading.

Don't use auto focus.  If you are shooting a scene with a known depth of field.  Disable AF and use a fixed aperture sufficiently small to make the entire scene within  the selected DOF.  You might need to use lights if you need a small aperture.

Tedolph

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Russ Houston
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Re: Don't use it.
In reply to tedolf, Nov 15, 2012

tedolf wrote:

Don't use auto focus. If you are shooting a scene with a known depth of field. Disable AF and use a fixed aperture sufficiently small to make the entire scene within the selected DOF. You might need to use lights if you need a small aperture.

Tedolph

Yep, autofocus on video is a pain.  Better to just focus once, then switch to manual and leave it there.  Especially if you're doing review videos, the camera won't need AF anyway.

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saywhathomie
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Re: Don't use it.
In reply to Russ Houston, Nov 15, 2012

Russ Houston wrote:

tedolf wrote:


Don't use auto focus. If you are shooting a scene with a known depth of field. Disable AF and use a fixed aperture sufficiently small to make the entire scene within the selected DOF. You might need to use lights if you need a small aperture.

Tedolph

Yep, autofocus on video is a pain. Better to just focus once, then switch to manual and leave it there. Especially if you're doing review videos, the camera won't need AF anyway.

Okay, just tried that and it didn't work. I can't bring the product up close or far away without it being blurry.

I'm shooting at 3200 ISO and f.25.

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tedolf
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Well, you are shooting.....
In reply to saywhathomie, Nov 15, 2012

saywhathomie wrote:

Russ Houston wrote:

tedolf wrote:


Don't use auto focus. If you are shooting a scene with a known depth of field. Disable AF and use a fixed aperture sufficiently small to make the entire scene within the selected DOF. You might need to use lights if you need a small aperture.

Tedolph

Yep, autofocus on video is a pain. Better to just focus once, then switch to manual and leave it there. Especially if you're doing review videos, the camera won't need AF anyway.

Okay, just tried that and it didn't work. I can't bring the product up close or far away without it being blurry.

I'm shooting at 3200 ISO and f.25.

wide open so of course you are going to get the minimum Depht of Field.  Stop down to f/8.0, manually focus on something about two feet from the lens and everything from 1.5  feet  out to about four feet will be in focus.

You may need to turn on some lights to get adeequate exposure.

Do you understand the relationship between aperture and Depth of Field?

TEdolph

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LincolnB
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Use a different approach
In reply to saywhathomie, Nov 15, 2012

Professional videographers don't go down the rabbit hole you're going down. They use manual focus, multiple camera angles, lighting designed for video, etc.

If you're using ISO 3200 and f/2.8 I'll bet you need more light. So get more light.

Try setting up two cameras - one at macro range for the product and the other for the demo. You could get a more professional looking video with a mid-range camera and a cellphone - with two camera angles - than trying to get one expensive camera do it all in one shot.

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saywhathomie
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Re: Well, you are shooting.....
In reply to tedolf, Nov 15, 2012

tedolf wrote:

saywhathomie wrote:

Russ Houston wrote:

tedolf wrote:


Don't use auto focus. If you are shooting a scene with a known depth of field. Disable AF and use a fixed aperture sufficiently small to make the entire scene within the selected DOF. You might need to use lights if you need a small aperture.

Tedolph

Yep, autofocus on video is a pain. Better to just focus once, then switch to manual and leave it there. Especially if you're doing review videos, the camera won't need AF anyway.

Okay, just tried that and it didn't work. I can't bring the product up close or far away without it being blurry.

I'm shooting at 3200 ISO and f.25.

wide open so of course you are going to get the minimum Depht of Field. Stop down to f/8.0, manually focus on something about two feet from the lens and everything from 1.5 feet out to about four feet will be in focus.

You may need to turn on some lights to get adeequate exposure.

Do you understand the relationship between aperture and Depth of Field?

TEdolph

A little bit. I know wider aperture = blurrier background but that's about it. As I said, I'm still learning.

To clarify. I should manual focus on the item in the middle of the table, then it won't be blurry when I move it closer or farther back?

Here's a picture of my current recording setup.

P.S, I appreciate the helpful comments. I'm soaking it all in! 

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Vlad S
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Learn the technique
In reply to saywhathomie, Nov 15, 2012

saywhathomie wrote:

My videos have a lot of a movement away and towards the camera. I shoot review videos and have to bring the product close up and set it back down again. Trouble is, the camera keeps focusing on a small bit of the video instead of the whole scope (Like my old camcorder does).

The earlier posters already mentioned that manual focus is the way to go, but I think it will help you to know that the actual technique for changing the focus during filming is called "focus pull." Professional videographers and film makers might have a dedicated professional focus puller, but you can find some DIY tutorials for amateur DSLR users. There are all sorts of tricks, and it will save you some sanity if you reuse other people's experience. Here's one such tutorial, but you may search for more for moving subjects.

Vlad

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tedolf
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The best thing to do....
In reply to saywhathomie, Nov 15, 2012

saywhathomie wrote:

tedolf wrote:

saywhathomie wrote:

Russ Houston wrote:

tedolf wrote:


Don't use auto focus. If you are shooting a scene with a known depth of field. Disable AF and use a fixed aperture sufficiently small to make the entire scene within the selected DOF. You might need to use lights if you need a small aperture.

Tedolph

Yep, autofocus on video is a pain. Better to just focus once, then switch to manual and leave it there. Especially if you're doing review videos, the camera won't need AF anyway.

Okay, just tried that and it didn't work. I can't bring the product up close or far away without it being blurry.

I'm shooting at 3200 ISO and f.25.

wide open so of course you are going to get the minimum Depht of Field. Stop down to f/8.0, manually focus on something about two feet from the lens and everything from 1.5 feet out to about four feet will be in focus.

You may need to turn on some lights to get adeequate exposure.

Do you understand the relationship between aperture and Depth of Field?

TEdolph

A little bit. I know wider aperture = blurrier background but that's about it. As I said, I'm still learning.

To clarify. I should manual focus on the item in the middle of the table, then it won't be blurry when I move it closer or farther back?

Here's a picture of my current recording setup.

P.S, I appreciate the helpful comments. I'm soaking it all in! 

is look at an on line DOF calclulator:

http://www.dofmaster.com/dofjs.html

Then you will have exact numbers as to where the field starts and ends based on where you are focusing, what focal lenght you are using, and what aperture you will need.

This is all much easier with a manual lens where all of this stuff is marked right there on the lens barrel.

No offense intended I am just very curious:

How did you wind up with a $1,000.00+ camera if you don't understand basic photography stuff?

Tedolph

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saywhathomie
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Could I.
In reply to tedolf, Nov 15, 2012

Could i use a combination of MF and AF?

As in, use MF with a 6.5 aperture to focus, then switch to area AF for actual recording?

If I do it right, I should be able to move around 4-5 all around right? I shoot 12-16 inches from the lens and move the product close up constantly.

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Dc5e
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Re: Could I.
In reply to saywhathomie, Nov 15, 2012

saywhathomie wrote:

Could i use a combination of MF and AF?

As in, use MF with a 6.5 aperture to focus, then switch to area AF for actual recording?

If I do it right, I should be able to move around 4-5 all around right? I shoot 12-16 inches from the lens and move the product close up constantly.

There should be 3 modes of focusing in videos: MF, AF, and Continuous AF.

Using Continuous AF will try to keep whatever is in the focus box in focus. This can give an amateurish look as the camera may constantly try to refocus if it thinks it's out of focus.

AF mode with Continuous AF turned off will allow the camera to autofocus whenever you half-press the shutter button.

MF mode requires you to move the focus ring on the lens to focus. If your camera is set up on a tripod, this can be hard to do without shaking the camera. It can also be difficult to quickly and accurately focus to a precise spot due to focus-by-wire.

Your best bet would be to stick with AF with continuous AF turned off and press the shutter button whenever you need to refocus (If pushing the shutter button causes shake, you could try using a remote shutter). The 14mm also cannot focus on anything closer than 7 inches, so if you hold anything closer than that, it'll just fail to focus on anything.

I would also recommend setting up as many lights as you can and setting the aperture the smallest (large F number) you can go (while keeping proper exposure) to get the most Depth of Field.

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tedolf
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This is getting way too complicated....
In reply to Dc5e, Nov 16, 2012

Dc5e wrote:

saywhathomie wrote:

Could i use a combination of MF and AF?

As in, use MF with a 6.5 aperture to focus, then switch to area AF for actual recording?

If I do it right, I should be able to move around 4-5 all around right? I shoot 12-16 inches from the lens and move the product close up constantly.

There should be 3 modes of focusing in videos: MF, AF, and Continuous AF.

Using Continuous AF will try to keep whatever is in the focus box in focus. This can give an amateurish look as the camera may constantly try to refocus if it thinks it's out of focus.

AF mode with Continuous AF turned off will allow the camera to autofocus whenever you half-press the shutter button.

MF mode requires you to move the focus ring on the lens to focus. If your camera is set up on a tripod, this can be hard to do without shaking the camera. It can also be difficult to quickly and accurately focus to a precise spot due to focus-by-wire.

Your best bet would be to stick with AF with continuous AF turned off and press the shutter button whenever you need to refocus (If pushing the shutter button causes shake, you could try using a remote shutter). The 14mm also cannot focus on anything closer than 7 inches, so if you hold anything closer than that, it'll just fail to focus on anything.

I would also recommend setting up as many lights as you can and setting the aperture the smallest (large F number) you can go (while keeping proper exposure) to get the most Depth of Field.

Just set the camera to F8, maybe F11 if you have enough light or use a video light.  Set the camera on manual focus.  Focus on something about two feet from the lens.  Leave it alone.  Everythig wiil be in foucs from about 1 foot to five feet.  Check a DOF table for exact numbers.  If you are going to need a super close up-closer than about one foot, you are going need a camera man.

Tedolph

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