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Shifting wb on Canon xha1

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Antonio de la cruz
Shifting wb on Canon xha1
on Dec 29, 2009 at 6:23:51 am

Hey, people first hope your are well. I just shot a scene for a short and now I'm looking at the footage and it seems that there is a slight shift of the white balance. I'm looking at it in a regular monitor that is not hd. I shot with the canon xha1 in 24f. shutter at 1/48. I made sure to set the white balance. I was shooting under fluorescent lights. The shift is very slight. Can that be corrected in post? Or do I have to shoot again? And what do I have to do to avoid that problem again if I shoot again?

Thanks,

Antonio


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Todd Terry
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 3:50:44 pm

By "shift" are you meaning that the white balance is just a bit off? Or that it "shifts" and changes throughout time?

If it's just a bit off, that should be an easy fix... tweakable by the color correction functions of most any editing platform.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Antonio de la cruz
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 5:59:30 pm

Hi, Thanks for your response. What I mean is that it shifts every 5 seconds or so. The change is very slight. But it continues through the 60 minutes of footage I shot. Again its visible but is very slight. Just wanted to know if I have to shoot again or if that can be corrected in post. I've been reading some stuff here and it seems that I should have the the camera at a different shutter speed to shoot with fluorescent lighting something to do with "clear Scan". I just would like to see if there any way that I can correct that since we put a lot of work into this shoot and the results were great besides that issue.

Antonio

antonio de la cruz


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Todd Terry
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 6:16:19 pm

Yep, you are seeing phasing of the flo lights, I'm betting.

You might be able to correct that in post... although it would probably have to be done manually at every phase shift and would likely be fairly tedious. It might be easier than a re-shoot, though.

I think the XHA1 works electronically identically to the XLH1, which is the camera that I use... if so, then yes, shooting in "clear scan" mode would likely fix it.

If it is the same as the H1, then toggle your shutter speed up up up as high as it will go. The last setting you get to (right after 1/15000) will be "CS." In the camera settings menu you can then define exactly the shutter speed for the clearscan mode. In north America under normal AC power the proper clearscan setting will probably be 60.5Hz.

In actuality though, the best choice is to not shoot under regular fluorescent lights... but sometimes that can't be helped. If you have to shoot with the flos (and I'm talking about regular plain ol' office fluorescents, not flicker-free instruments such as Kinos), then try to avoid mixing them with other types of lighting, such as tungsten. It's the fact that the phasing is causing slight changing in the ratio of the mix of the lighting that is causing your color shifts.



T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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Antonio de la cruz
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 6:53:12 pm

Thanks! What I will do is edit the short film and simply do the correction on the shots selected. Thanks for the advice!

antonio de la cruz


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Alan Lloyd
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 8:50:03 pm

If your editing program has a good vectorscope that might make your life somewhat easier.


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Antonio de la cruz
Re: Shifting wb on Canon xha1
on Dec 29, 2009 at 9:27:44 pm

Thanks again. I was depress for a moment there after watching the footage yesterday.

be well,

antonio

antonio de la cruz


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Peter Ralph
Re: Shifting wb on Canon xha1
on Dec 30, 2009 at 4:15:13 pm

Todd, you say "It's the fact that the phasing is causing slight changing in the ratio of the mix of the lighting that is causing your color shifts."

So when shooting under office fluorescents the phasing should be less noticeable if you shoot without additional tungsten fixtures?

Peter Ralph

http://www.shootingbynumbers.com


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Todd Terry
Re: Shifting wb on Canon xha1
on Dec 30, 2009 at 5:26:12 pm

[Peter Ralph] "So when shooting under office fluorescents the phasing should be less noticeable if you shoot without additional tungsten fixtures?"

Right.

What is happening when the flos are phasing is that they are not actually changing in color temp, but they are changing in intensity. Very very slightly... not enough for your eyeball to see... but enough so that is changing the ratio of the flo lighting compared to the non-flo lighting which does not phase. Therefore the color temperature of the mixed light is changing because the ratio keeps changing.

If you were to just shoot under the office flos alone, you likely would not see any color phasing at all. Now, you might see some slight exposure phasing, but usually it is very very minor. And if you shoot with a camera that has a clearscan mode set to the proper frequency, you shouldn't see it at all.


T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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