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-   -   Grey cards for White Balance?? (https://www.dvinfo.net/forum/open-dv-discussion/114510-grey-cards-white-balance.html)

Guy Godwin February 10th, 2008 08:53 PM

Grey cards for White Balance??
 
Do you guy's know why several still camera photographers use a grey card to set a custom white balance? How does this impact a video camera?

http://www.pictureflow.com/products/.../purchase.html

What is the difference for still vs Video?

Guy Godwin February 10th, 2008 08:59 PM

Sorry for the thread....
it looks like this has been hammered out in others

Michael Nistler February 11th, 2008 12:35 AM

In fact, sometimes we don't use 18% photo grey but instead trick our camera white balance to produce special effects on the fly (rather than color correction in post):
http://www.warmcards.com/

Still, I like the double-duty use of the Clear-Star microfiber lens cleaning cloth that's 18 percent photo grey:

http://www.cleanstar.net/products.htm

For those that use an electronic light meter like the Sekonic, we can calibrate the meter using 18 percent photo grey as a reference:
http://www.sekonic.com/products/products.asp?ID=131

Regards, Michael

Guy Godwin February 11th, 2008 08:45 AM

Quote:

For those that use an electronic light meter like the Sekonic, we can calibrate the meter using 18 percent photo grey as a reference:
http://www.sekonic.com/products/products.asp?ID=131

Regards, Michael
The Warmcards or the cloth would have been just fine.
Now you toss in a "gadget". I am thinking a little bit of money for cards and now you really got me asking questions....

What is the best? Is this meter simple to use and how does it work?

Alessandro Garabaghi February 11th, 2008 11:01 AM

I picked up an ExpoDisc and have been very happy with it. It helped a lot this sat when the clouds were moving and the light source kept changing a lot.

www.expodisc.com

Michael Nistler February 11th, 2008 01:41 PM

Quote:

Originally Posted by Guy Godwin (Post 824250)
The Warmcards or the cloth would have been just fine.
Now you toss in a "gadget". I am thinking a little bit of money for cards and now you really got me asking questions....

What is the best? Is this meter simple to use and how does it work?

Rehi,

It's a bit on the high-end for most, unless you consider yourself at the high-end of a prosumer, heading to become a pro, or simply love toys! Hopefully the link above, searching the internet, and the archives here will give you specifics. But in summary, it does have several advantages over on-camera zebras - here's a few off the top:

- ability to independently measure many narrow beams of light (ratio analysis)
- ability to automatically average the light over selected areas
- ability to also measure (incident) three dimensional light on the subject itself
- make your client think you're sexy and worth your seemingly high fees

My advice - don't walk, run, flee, fly and be free before the inertia drags you in with the rest of us!

Happy Trails, Michael

Jim Andrada February 11th, 2008 10:41 PM

It's a great meter for large format photography. Particularly if you don't mind spending 30 minutes or so mucking about to find the correct exposure for each shot. I think it's bigger than some of the newest small cameras.

I also have a real antique (bought new 40 years ago) that reads a 1/2 degree spot and is incredibly accurate. It works by sliding two geared neutral density prisms in opposite directions, thus increasing the neutral density, until the reference spot matches the output of a calibrated lamp bulb and effectively "disappears". It even has a built in voltmeter to use in calibrating the bulb.

All great stufff for "very still" photography.

Liam Hall February 12th, 2008 06:06 AM

Quote:

Originally Posted by Guy Godwin (Post 824250)
The Warmcards or the cloth would have been just fine.
Now you toss in a "gadget". I am thinking a little bit of money for cards and now you really got me asking questions....

What is the best? Is this meter simple to use and how does it work?

It's an exposure meter. Stick your money back in your pocket; it has nothing to do with color balance. In fact, you don't need any fancy products to set or to cheat white balance.

Jim Andrada February 12th, 2008 11:40 AM

Exactly. Great meter and I like it, but...

I wouldn't bother with it for video. Probably woudn't bother with it for most small format digital still work either.

Michael Nistler September 5th, 2008 01:13 AM

Follow-up on light meter benefit
 
Rehi all,

Yesterday I was outside filming at a wicked time of day in the summer: 3:30 - 5:30PM. It was clear the sun was going to be washing out the pix at some locations, but how much and what would be the best location, etc?

Now here was an ideal situation to check out various lighting locations without have to haul out a camera, play with ND filters, f-stops and shutter speed. Within a matter of moments, the light meter not only gives quick and accurate spot reading on a hot spot (like a white building in the background), but it's soooo easy to do comparative across various points in a scene (to compare f-stop ratios). It's also a simple process to test various areas, camera angles, etc - this allows a quick way to scout the best location. The clincher was showing the client the problem with some of their favored locations - push the button, show them the numbers, and it's easy to convince them to move on to a better location (maybe next time they'll agree to shoot at the golden hour...)

Regards, Michael

Jim Andrada September 5th, 2008 11:07 AM

Good video use for the Sekonic just occurred to me - it would be the cat's meow for checking evenness of green screen lighting.

Michael Nistler September 6th, 2008 06:31 PM

Jim,

Yes, it's a cool toy for chromakey light balancing but here's a situation where the camera zebras are probably best. Using the light meter route, we move the light then check several points and try again. Using zebras, it's easy to dynamically move the light while watching the entire green screen and give real-time verbal feedback to the lighting person. And on the camera, bump up/down the zebra IREs to ensure the balance is uniform across the entire screen.

However, I will profess this process may not work well for everyone. If the studio is short and the camera can't get back far enough to view the entire green screen, then the light meter is probably quickest. And realistically, the lighting concern is probably most pronounced near the sides/corners of the screen which may be outside the camera range. Or perhaps the camera doesn't have zebras at all in which case the light meter can save the day.

Regards, Michael

Jim Andrada September 6th, 2008 08:09 PM

Well, I have to admit that I never would have gotten the Sekonic for video. But for working with my 5 X 7 Linhof view camera it's hard to beat. I had the meter well before getting involved with video.


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