Setting the f-stop before doing a manual white bal

R

rc444

Well-known member
Hi there,

I don't have a light meter and wanted to know what is the appropriate f-stop before you do a manual white balance on a video camera?

Assuming Ansell Adam's colour theory of 18% grey, on a sunny day, would it be reasonable to set the video camera at f5.6 before doing the manual white balance?

It is just that I'm unsure whether to go for f2 or f5.6. If I go f2 and then manual white balance, I'm afraid all the other colours may be washed out, whereas... if I go 5.6, then, following Ansell's theory the white would be at 18% average, this would susequently mean that all other colours would reproduce at around the 18% average. Is my understanding correct? So is f5.6 good to go for? FYI, this is a news doco I'll be shooting at midday, so I am simply wanting to faithfully re-create the conditions and do nothing fancy.

Appreciate your help
David
 
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The 18% gray you are referring to is something related to exposure, not white balance. With white balance, there is not a certain F-stop you must use. You simply need to achieve proper exposure (not over or under exposure.)

Colors being "washed out" should not even be an issue, because there should NOT be any colors in your frame when white balancing.... just a properly exposed white card.

For best custom white balance results, use a white card (make sure the object you use is a 'real' white... many papers, boards, and similar items can have a cold or slightly warm cast. Simply expose the card so it is not blown out or muddy gray. Exposing the card at a marker level of 50%-60% should be sufficient.

As long as the light hitting the white card is the same color temperature cocktail of light hitting your set, you are good to go.
 
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What I explained is the normal way of getting correct color temperature white balancing. Of course many Dp's and cameramen, use tricks and unconventional ways of balancing to fit the style and look of the film/piece... and this is usually in the act of purposefully mis-balancing the camera. Once you know how to properly white-balance, you can then trick the camera to get new looks and styles.
 
DSC Labs has a manual for students. There are a few articles, but it also contains several charts (chip chart, 18% gray, etc.) and white balancing cards (warm, cool, true white).

I bought mine at my school's bookstore, but you might be able to find it online at a reseller.

http://www.dsclabs.com/student_edu.htm
 
no no, you're right. i was referring to your signature. if the Lighting forum is a "connecting flight" then the Audio forum must be a "crash landing"!
 
I prefer attractive AD's. It's really fun to mess with them.

Anyway, speaking of airplanes... someone call homeland security because this thread is officially hijacked. Either start negotiations or just drive it into audio forum.

Thanks.

hahaha.
 
be careful of the words you use on-line Ryan. Big Brother has his eye on you now since you used the "Key Words", ie: home...., hijac..... i highly recommend you get a new computer and a new ISP address asap!!!
 
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