Help With Stage Focusing

[Brad Ridgeway]

I am an amateur videographer who has been shooting local dance recitals for about 7 years using small Sony Handycams. The CX160 is right in front of the stage capturing closeups at an angle, the XR500 is manned by me from a platform just behind the left side floor seating, and the XR550 is fixed in the balcony just to the right of the sound booth (all of these locations can be visualized in the attached photo of the venue).

I get very good results with this setup each year but I still can't nail down the focusing of the fixed XR550 in the balcony. If I use auto focus it ends up taking a while to refocus when the lights go dim and then come back up. If I manually focus to infinity, it always seems like the dancers in the front of the stage are out of focus. Each year I try manually adjusting the focal length to a different setting but it always seems that the dancers in either the front or the back of the stage are out of focus.

Does anyone have any tips on how to get this camera to best focus on the entire depth of the stage (it's really not as far as it appears in the photo but I have no idea what is the actual distance)? Is it even possible?

Thanks!
Brad

[Noa Put]

Have you tried using spotfocus? You should never use autofocus with these unmanned cameras for stage performances, like you said once the lights go out the camera will go out of focus and can take a long time to refocus when the lights go on again.

It also can happen that the autofocus gets confused if there is not enough fine detail, like when you have an empty stage and a black backdrop the camera only sees 2 solid colors and this can cause the focus to hunt or the camera not being able to focus if you plan on locking the focus if you let the camera prefocus. Unmanned camera's should always be set to manual focus, something you should do before the show starts, you could ask to flood the stage with white light and ask for some people to stand on the stage or print a big focus chart and put it on a lightstand in the center of the stage so the camera has something to focus on.

[Cary Knoop]

Originally Posted by Brad Ridgeway

Each year I try manually adjusting the focal length to a different setting but it always seems that the dancers in either the front or the back of the stage are out of focus.

Only a certain region is truly in focus, that region gets larger if you set your aperture smaller.

[Steven Digges]

Since that is your long shot from back at the mixer I suspect it is a depth of field issue. You say, "ether the dancers in front or the dancers in back are out of focus".

Do you have that camera set on its maximum zoom? Long focal length (zoom) + maximum aperture (wide open) = shallow depth of field (focus area). The wider you make that shot the more depth of field you will have. Setting smaller aperture manually can also increase the DOF, if you have enough light to do this. At the risk of degrading image quality increasing iso/gain will also allow smaller apertures. It all depends on the amount of light you have to work with. Some stages are brightly lit, some are very dim by exposure standards.

Kind Regards,

Steve

[Noa Put]

Originally Posted by Cary Knoop

Only a certain region is truly in focus, that region gets larger if you set your aperture smaller.

The xr550's sensor is tiny, even with the iris wide open everything will be in focus front to back if you have the entire stage in frame, at least I assume that was how the camera was framed as it was a fixed unmanned camera set up in the back.

[Noa Put]

Originally Posted by Brad Ridgeway

If I manually focus to infinity, it always seems like the dancers in the front of the stage are out of focus.

Can you post a framegrab so we can see how it looks like?

[Brad Ridgeway]

I would have to dig for some footage. I think I used auto last year so I have to go back for some examples. This year's rehearsal is tonight and recital is Saturday. Going to play around at rehearsal tonight but the lighting, costumes, and makeup are never the same from rehearsal to actual recital day.

[Brad Ridgeway]

So basically I need to find the best way manually focus on something in the middle of the stage. One year, I thought I had this down. I zoomed in to an object in the center of stage, manually set the focus on that object, and then backed out to frame the entire stage. I shot the whole recital at this setting only to find out afterward that the wide shot was not focused as well as I had thought (I believe the front of the stage was out of focus that year). Is this not the correct way of doing it?

As you can see, I am very amateur at this. I like everything to be automatic since I don't have much knowledge of these subjects. These small cameras actually do very well for the recitals. The only settings I really change on the camera are white balance to Indoor and AE shift to -4 (stage lighting is typically fixed VERY bright white). And I also try to set the focus manually on the wide fixed cam. Auto focus usually works well for the close-up fixed cam and my manned cam since I typically use the fixed wide shot at the beginning and end of every performance.

I pretty much have my process and routine down after doing this so many years except for the focus of this one cam which is not terrible but each year I strive to get it better.

This particular recital is huge. I usually end up with 7+ hours of footage (per camera) for a single day and end up delivering the final product in a three DVD set.

[Noa Put]

I zoomed in to an object in the center of stage, manually set the focus on that object, and then backed out to frame the entire stage

Here is your problem, the xr550's lens is not parfocal, meaning if you focus like you do it will become out of focus if you zoom out again. If the camera is supposed to cover a fixed frame the entire performance then set the frame first and then let the camera prefocus and lock it.

If you need to follow dancers on stage and zoom in and out then also don't focus like you described because you will get in and out of focus shots but either let that camera handle focus automatically or each time you stop zooming let the camera refocus automatically and then lock the focus.

[Brad Ridgeway]

Originally Posted by Noa Put

If the camera is supposed to cover a fixed frame the entire performance then set the frame first and then let the camera prefocus and lock it.

Will play with this tonight at rehearsal. It makes sense. I think I just need a predominate object that the cam can easily focus on in the middle of the stage.

[Brian Crow]

To get as much of the stage to be in focus, you can take advantage of the fact that when you focus on a point,the region of good focus extends about twice as far beyond the point as it is in front. Therefore you should focus on a point one third of the distance back rather than halfway back.

[Ron Evans]

The best way I have found with the small Sony's as unattended full stage cameras is to frame the shot then use spot focus on a point as Brian mentioned about 1/3 into the stage. You will then find everything on the stage front to back stays in focus. I set a gain limit, so they don't try and see in the dark, fix shutter( in my case in NTSC 1/60 ) ,use AE shift for the dial and set for the brightness you want. In all but really dark spotlit actors this will work well. I make the assumption that the tracking camera will catch the spotlight action anyway.

[Paul R Johnson]

If the camera at the back of the auditorium is zoomed in more than by 50% of the range, the depth of field at the narrower angle is reduced considerably, and even worse, if the iris opens up, this explains the lack of sharpness. I record theatre performances as a big part of my job, and locked off cameras are always a risk. Any form of autofocus fails for theatre, and even on manual, you will become good at focusing as things change. It's often the case that the nicest camera is the one you actually operate, leaving the cheaper and less manual friendly cameras for the lock off. This is where 4K consumer cams have a small advantage - you can leave them on a wider setting, and then crop in the edit and the depth of field can be greater. I guess you are stuck with what you have - if it's a problem, then maybe an assistant would be worth the money to make sure it's in focus? For theatre I have never used autofocus it rarely has the ability to focus on the critical element because it cannot determine what is the critical element! That moving dancer may well NOT be the thing to focus on - but losing focus on the really important bit in a random fashion is just unacceptable.

Locked off and manually focussed cameras are the workable solution, but they need to be sensitive so they can work with a narrower iris setting, and have a lens with proper and repeatable distance setting. That's pretty much it really.