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12-16-2008, 01:24 PM   #1
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Need tips adjusting WB for projector screenshots and overall picture takin technique

Hi!
I am trying to find the best way to take pictures of my front projection system.
First, I am not sure how to calibrate the white balance.
Do you think projecting a white screen and using that for calibration is a good idea?
Second, if anyone has experience doing this..I will be happy to get some tips as well.
I am using a 50mm prime right now with decent results but wouldnt mind some improvement.

12-16-2008, 02:27 PM   #2
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Yes, using a white screen with your front projection system is a good idea for adjusting a custom white balance.

But you don't say if you are projecting still images or videos. If still images, then exposure will be as light demands it, but if video (moving), then you have to account that every frame stays in screen for no more than 1/30 second, and it is very possible to photograph the interlacing band between frames, even if using shutter speed lower than 1/30.
12-16-2008, 02:29 PM   #3
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Are you trying to take a picture of the screen or of the projector? Not sure what you're asking... and don't worry, before too long someone will chime in about using RAW and not to worry about WB.
If you do want to use jpeg, then select the autowb and adjust all the sliders accordingly to what you see fit. I have this feature on my k10d, though not sure if older cameras had it, and what you use.
Maybe post some examples of what you're trying to shoot?
12-16-2008, 03:13 PM   #4
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By shaolin95
Thats what I am doing.
Im using RAW but I can still set the white balance instead of trying to guess later.
I am pausing the movie before taking the pic and its all 1080p so no interlace issues either.
I tried using a white image from the projector and some screenshots came out with great color but others looks totally weird which didnt make sense to me.

I am sure someone in this forums has done this before...right? :-)

BTW, any ideas why the images uploaded in image shack or photobucket look punchier than when I post them on a forum?


Last edited by shaolin95; 12-16-2008 at 06:07 PM.
12-16-2008, 07:16 PM   #5
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I am sure someone in this forums has done this before...right? :-)

I dont know if anyone else has tried this shaolin but thanks for the idea. I have a front projector home cinema and a stack of movies to play with.
As for the white balance set it on auto and when you process your image in whatever RAW converter you use you dont have to guess, you can try every WB and see which is best for you. Hmmm must go and clean all the junk out that the missus has been storing in my cinema..........
12-16-2008, 09:02 PM   #6
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QuoteOriginally posted by baldrick Quote
I am sure someone in this forums has done this before...right? :-)

I dont know if anyone else has tried this shaolin but thanks for the idea. I have a front projector home cinema and a stack of movies to play with.
As for the white balance set it on auto and when you process your image in whatever RAW converter you use you dont have to guess, you can try every WB and see which is best for you. Hmmm must go and clean all the junk out that the missus has been storing in my cinema..........
Hope to see some images from your setup soon.
QuoteQuote:
As for the white balance set it on auto and when you process your image in whatever RAW converter you use you dont have to guess, you can try every WB and see which is best for you.
Thats precisely what I mean...thats guessing or making it look good for me but I want to capture exactly what its been displayed not what my eyes like when I am editing.
That will also help me compare different renderers and other tweaks to my HTPC set up.
BTW, the projector is an Infocus 7210 (720P) and the screen is 120" wide.
Regards
12-17-2008, 05:29 AM   #7
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IMHO there is no way to calibrate white balance exactly. It's always a subjective adjustment.

For example, a white sheet of paper is the most common test subject. But again, the whiteness depends on the light source. So when is the paper white (or what exactly is white)?

Also, projecting a "white" image on your screen is not exact, because it depends on the projector adjustments.

My idea would be to include a white card or a gray card in one of the photos, then use the eyedropper tool to set the white/gray colour adjustment in your photo editor.

When you know the amount of correction, you can batch process all pictures using the same correction.

But by all means, use a fixed white balance, not auto, to get consistency.
12-17-2008, 08:17 AM   #8
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QuoteOriginally posted by Terje-L Quote
IMHO there is no way to calibrate white balance exactly. It's always a subjective adjustment.

For example, a white sheet of paper is the most common test subject. But again, the whiteness depends on the light source. So when is the paper white (or what exactly is white)?

Also, projecting a "white" image on your screen is not exact, because it depends on the projector adjustments.

My idea would be to include a white card or a gray card in one of the photos, then use the eyedropper tool to set the white/gray colour adjustment in your photo editor.

When you know the amount of correction, you can batch process all pictures using the same correction.

But by all means, use a fixed white balance, not auto, to get consistency.
I noticed something interesting. When opening the photos with photoshop, the RAW window will show up as usual and if I did auto on the color temperature most of the time it will select 7500 or close to that which, when I checked my projector, was the color temperature set in the menu (Infocus are normally very accurate in their color temps). Some how I changed the color temp from 6500 to 7500 and forgot to change it back but the point is, I found it very interesting that photoshop will somehow know what the projector color temp was.
Does that mean that when I set back my projector to 6500...thats the color temp I can manually set for batch conversion?

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