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Home: Video University Forums: Sony DV and DVCAM Forum:
Randomly changing color temp./ PD 150

BVmando
New User

Dec 3, 2004, 11:24 AM

Post #1 of 7 (1698 views)
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Randomly changing color temp./ PD 150	Can't Post

While using our universities PD 150, we've shot some interviews lately where the white balance seems to change from yellow to blue and back again in a random manner in the middle of the shot, even when left on manual white balance.

Ususlly this happens under fluorescent lights

Usually this happens when I have the shutter speed set high and the iris open all the way (I use this to manipulate depth of field) but I've seen it happen in other peoples video who I assume would not use the same trick.

Anyone else encounter this?

Yesterday we began an interview with a light kit under fluorescents, and it began happening again. I turned off the overhead fluorescents and it went away, even though my shutter was set as high as 500 during the interview. So I'd assume it was the lights that I removed, but I've been shooting in similarly lit situations for a long time and I've never had this problem before, and I just started changing shutter speed this year and now I see the problem quite a bit.

Anyone?

JesseR
Enthusiast

Dec 6, 2004, 1:19 PM

Post #2 of 7 (1640 views)
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Re: [BVmando] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

I have heard that Fluorescent lights will alter your images. For this reason I was told to always white balance with my Minus Green warm card. Since doing so my cameras hold good.

--
Jesse R
www.Take5Video.com
www.JesseReich.com

Spencer Wood
Novice

Dec 14, 2004, 4:59 PM

Post #3 of 7 (1608 views)
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Re: [JesseR] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

Yes, shooting under Fluorescent lights causes the same problem with my VX2000. I can't explain why it happens... probably something to do with sync to the lights frequency.

Try locking in your shutter speed to 125 or less. That fixed the problem for me.

Shawn Lam
User

Dec 20, 2004, 1:25 AM

Post #4 of 7 (1567 views)
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Re: [Spencer Wood] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

I experienced the same on a PD-150 when in auto and it ruined some good footage. I'm not sure if shutter speed played a role though as mine was set to 60 fps. I agree that manual white balancing in that situation is critical.

I usually use a white card. Jessie could you explain what a minus green card is?

Thanks,
Shawn

Shawn Lam, MPV

Shawn Lam Video
Vancouver BC
BCPVA President
EventDV Columnist
2008 WEVA CEA silver award winner - Theatrical Productions

celycom
Novice

Jan 6, 2005, 2:50 PM

Post #5 of 7 (1477 views)
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Re: [BVmando] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

Take a look at my page http://www.cely.com/digital/test.html for a discussion of this issue. It is an unavaoidable problem with some cameras (like the PD-150) and fluorescent lights. The BBC advises that their cameramen NEVER shoot under fluorescent lights with any sort of shutter enabled, and since you cant really disable the shutter in a PD-150... there you go!

Best of luck!

Spencer Wood
Novice

Jan 10, 2005, 2:08 PM

Post #6 of 7 (1445 views)
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Re: [celycom] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

Celycom,

Hey that's great to actually see posted examples of what can happen!

One thing I'd add though, to clarify your point... Not locking in a shutter speed, as suggested, makes a cam like the VX2K or a PD150 default to "auto shutter speed" mode. And that can still lead to problems, because if the scene is relatively bright, as the cam may try to bump the shutter speed up to an unacceptable level in it's attempt to control the exposure. Thus your locked in WB may still go haywire.

So as far as these cams are concerned, locking in a manual shutter speed (and WB) is the only solution that does work. You just need to keep it the shutter speed kinda slow as I explained above.

celycom
Novice

Jan 16, 2005, 2:04 PM

Post #7 of 7 (1382 views)
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Re: [Shawn Lam] Randomly changing color temp./ PD 150 [In reply to]	Can't Post

Shawn,

I noticed you asked about a minus green card... while I personally think they are a rip off, they are actually very, very convenient ways to adjust your color balance. Generally, they are a card for color balancing that is slightly blue and very slightly green, usually about the equivalent of 1/4 CTB and 1/4 PlusGreen color gel. When you use them to color balance your camera, it is shifted the otehr way - towards the warm. The effect is much like a Tiffen 812 or coral filter. WarmCards sells them on their website at http://www.warmcards.com/, and they offer a well-made, beautifully packaged product.

The only reason I think of them as a rip off is that I've been doing the same thing for free for nearly 25 years! Just get some of the afore mentioned gel from a friendly gaffer, and hold the gels over your lens when you color balance... Voila! Also a lot cheaper than the Tiffen filters! BTW, I got a large size Lee gel swatch book, and took out everything except the CTB and PlusGreen gels in 1/8, 1/4 an 1/2 strengths. That way I can vary the amount of warmth I want from shot to shot.

Finally, a disclaimer... personally, I wouldn't spend the money for WarmCards, BUT they are more convenient than holding gel over the lens, though not a flexible. Also, as I said, they are beautifully made and well packaged... they are a good product, just not my cup of tea. Good luck!