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-   -   any help appreciated ....please (http://www.dvinfo.net/forum/jvc-gy-hd-series-camera-systems/471883-any-help-appreciated-please.html)

Tom Stretton January 28th, 2010 11:23 PM

any help appreciated ....please
Hi everyone
I have a couple of problems i wonder if anyone could help,I'm a relatively new to the Jvc 110u but I'm videoing a show over four nights in a theater,first off because of the constant changing of the light for example one minute people are bright as ghost and then then very dark,for a while i was switching the filter switch to compensate but it was so difficult knowing what light was coming next then i changed the shutter speed which seemed to help.also i just cant get to grips with the back focus procedure so consequently I'm for ever having to adjust the focus as I'm at the back of the theater would you think the auto focus would be the best solution as Ive never used it before. any help at all would be very much appreciated
thank you in anticipation

Ed Dooley January 29th, 2010 02:15 PM

The reason you've never used the auto focus is because there is no auto focus on that camera. Back focus adjustment is very easy, focus on something 9-10 feet away while zoomed all the way out, then zoom all the way in and adjust the back focus till it's sharp, back out again and readjst the back focus. Do it a few times until it's sharp when wide and zoomed in.

Tom Stretton January 29th, 2010 04:42 PM

thanks ed
thank you for your answer, I'm sorry i think i meant focus assist so ill give that ago(there is just so much to learn about this camera)
thanks again Tom

Brian Standing January 29th, 2010 10:34 PM

I would not recommend adjusting the shutter to deal with rapidly changing light conditions. Leave it at 1/48 (or 1/50 if you're using PAL). Having the shutter at other speeds can create either a stroboscopic or a slow-motion effect. This will be noticeable to viewers watching the footage as the shutter speed changes. Using the ND filters is fine, but might not give you a very fine level of control, and if you're shooting continuously, there will be a visible "clunk" as the filter slides into place.

Instead, I would recommend using the iris to adjust to changing light conditions. There are three ways of doing this:

1. Manually, by turning the wheel on the lens. If you use this technique, a good method is to set the zebras in the viewfinder to "over 100" and turning the wheel until all zebras stripes just barely disappear.

2. Hitting the temporary auto iris button by your right pinky on the handgrip on the lens (near the zoom rocker switch). A good technique is to zoom all the way in on the subject's eyes, manually set the focus, then hit the temporary auto iris button, then zoom back. This will lock critical exposure and focus even after you've gone to a wider angle.

3. Turning on the auto iris slider switch near your right pinky, on the handgrip. This will automatically adjust the iris as light conditions change. Be warned however, that under backlit conditions, you may get proper exposure on the background but subjects in the foreground may be in silhouette.

Kennedy Maxwell January 30th, 2010 01:10 PM

any help appreciated ....please
It seems to me that this an awfully big project to attack with such limited experience.

Visually I suggest using auto iris. The camera has good, smooth auto response and most likely will be better than trying to twist around with the iris ring.
I would not do a lot of zooming. I suggest a medium shot, that will minimize the iris' exercising and minimize focus problems. Also a lot of zooming can quickly become a distraction.

Audio pick-up was not mentioned in you thread, yet it is equally important in producing a good quality video. Is the production a musical performance, drama or variety show?
Rather than trying to pick up the sound with the built-in mike I suggest that you take a "line" feed from the house audio system, if available. . . or at the least run a stage mike from the lip.

White balance to white stage lights (up full), and good luck.

John Sirb January 30th, 2010 02:12 PM

Also I think if you're shooting from the back of the theatre, your not going to need to change your focus once it's set. as far as the lighting issue, I shoot quite a bit of live theatre and it can be my biggest headache. while going auto iris is a good suggestion if you haven't done of number of these, i generally run on manual, expecially if I know the show and can anticipate big lighting changes.

Burk Webb January 30th, 2010 04:50 PM

Another back focus tip, make sure your iris is wide open. You want your depth of field as shallow as possible so that you can get the most accurate focus. Put in the ND filters and crank up the shutter if you have to. A star chart can help as well, just print this out and go to town:

Creative Video > Articles > Free back-focus chart

Exposure is going to be tough and I've had iffy luck with auto. As mentioned above try and expose for the faces and let other stuff land where it will. of course take this with a grain of salt, we have no idea what the show looks like.

If your shooting 30p try and set the shutter at 60, if 24p try and set at 48. This should give you natural motion blur. Use the iris ring to ride the exposure if you have to. Try and avoid dropping in the ND filters.

Good luck and hope this helps.

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