White Balance and ND Filter question

Hello .

So I'll be getting an ND filter and White balance card pretty soon .


First of all I have a question about White Balance cards . Why a piece of white paper costs over 15-20 dollars ?

I am looking to get 18% / 30cm white/gray card simply because this is the only card avaliable right now at the local photo store . Is this the right one to go ? Is it too expensive ? Shall I get it ?

Secondly I never used an ND filter and I was wondering which one should I get ? I would love to get some shallow depth of field outside without getting over 1/48 . Any filter you would recommend me ?

Thanks in advance.
 
The white/grey card (like the ND filter) is specifically engineered to reflect all frequencies of light equally, thereby not coloring the reflection at all. It's an extremely specific white and gray, not jsut any white and gray which would be considered "Close Enough" by 90% of the public... this is for people for whom tight quality control on their images is of crucial importance.
 
And those will work, given ideal lighting. The trick is when lighting with lower CRI. If the item absorbs any frequencies, it'll potentially shift the WB slightly (note: slightly -- again, the expense is for great, not good).
 
Instead of using color balance cards, are you able to adjust the kelvin temperature on your camera manually? If not magic lantern can be downloaded into some cameras, and will give you the option, of changing the color balance to whatever you want it. Don't waste money on white balance cards.
 
I don't think changing it manually is a good option since I want to have more room to work in post and get the look I want instead of spending time on figuring out whats the best kelvin to go for the specific shot.
 
But you can still do the same thing and white balance the light to white, with magic lantern. You just adjust it till it's white, which is the same as using a white card.
 
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To the people suggesting simply "eyeballing" it, heed at your own risk. Yes, you can get it "close enough", and if you're happy with "horseshoes and hand grenades" accuracy, then I guess that's fine.

An 18% grey card is (as pointed out) specifically and carefully done to reflect 50% of all the visible light frequencies equally. It is better than a white card in as much as if they image is overexposed, you won't be getting some of the colours too "hot" for your camera to measure. Also, because it reflects 50% of the incidental light, you can use a histogram to expose by getting the spike in the middle, exactly where 50% should be. Strangely enough, film photographers used to have to compensate an extra 1/2 stop when using an 18% card, as you technically should use a 13% card to set exposure. But now, with digital cameras and histograms, the 18% has finally proved more useful by centering the spike in the histogram.

White balance is about far more than just getting the colour temperature correct, particularly when shooting with sub-pro lighting. Temperature will get your blue/yellow balance, but a proper white balance setting will also dial in a compensation for green/magenta, especially important if you have any fluorescent bulbs in the scene.

Anyway, if you were interested in how to do it properly, I hope that helps.

CraigL
 
To the people suggesting simply "eyeballing" it, heed at your own risk. Yes, you can get it "close enough", and if you're happy with "horseshoes and hand grenades" accuracy, then I guess that's fine.

Hm. I'd agree on lower end cameras. Not so much on higher end cameras.

That said, it's about knowing your lights, knowing the colours they make and making educated, creative decisions based on that. I've shot 4800K white balance in the past, I've shot 2000K white balance in the past, and I've shot 7000K white balance, using lights that weren't necessarily balanced at those temps - simply for looks I wanted to achieve. Just because my lights weren't balanced at that exact temperature, doesn't mean my choice was incorrect.

Similar to exposure - if my meter reads someone's face at f/4.0 and I shoot at f/2.0, having their face two-stops over, it doesn't mean my exposure is incorrect (as long as it's within the latitude of the stock, having done earlier tests ;))

But then, we're getting into being a real DP ;). I don't think I've ever worked with a DP who has used WB cards.
 
On our higher end productions we usually shoot a chip chart each scene, but that's more for post color correcting.

"Eyeballing" the color temp is fine IF you know what you're doing and it remains the same the entire scene. A master carpenter may eyeball a cut from time to time, but the guy is experienced in what he's doing. If you've never used saw before you better measure twice.

Auto-white off a card is great IF you set it for the scene and don't touch it. What you don't want to do is change it form shot to shot or auto-white every shot. It will be a little different.

Whatever method you use, do it at the top of a scene and don't touch it. Shots in a scene need to match.
 
Hm. I'd agree on lower end cameras. Not so much on higher end cameras.

That said, it's about knowing your lights, knowing the colours they make and making educated, creative decisions based on that. I've shot 4800K white balance in the past, I've shot 2000K white balance in the past, and I've shot 7000K white balance, using lights that weren't necessarily balanced at those temps - simply for looks I wanted to achieve. Just because my lights weren't balanced at that exact temperature, doesn't mean my choice was incorrect.

Similar to exposure - if my meter reads someone's face at f/4.0 and I shoot at f/2.0, having their face two-stops over, it doesn't mean my exposure is incorrect (as long as it's within the latitude of the stock, having done earlier tests ;))

But then, we're getting into being a real DP ;). I don't think I've ever worked with a DP who has used WB cards.

The quality of the lights has FAR more to do with it than the camera, IMHO.

You're talking about having a baseline and making creative choices, quite different. If you're happy setting the colour temperature and ignoring any green/magenta shifts, then that's cool. There really is no "incorrect" as long as you're making a conscious decision.

And again, with the exposure example, you measured to find the f/4.0 right? That's the first step, then adjust to achieve desired results.

As for a real DP not using a WB card, I expect that's a matter of choice. If you're comfortable that your particular camera doesn't have a specific colour shift (or have already manually corrected for it) and if you know the lights you're using very well or if you're shooting outside, then sure you can just manually dial it in, as well as any shift compensation. If you're trying to do a bunch of things on a typical (for me at least) shoot, 5 seconds with a grey card seems like a far better use of my time.

Really knowing your monitor, how it looks under different lighting conditions, what the camera peculiarities wrt colour balance and fully aware of what your lights do are complications that someone starting out especially could probably do without. However, regardless of my experience level, I don't think I'll ever abandon the grey card; besides it's often quicker to hit the auto button than manually adjust the temperature up and down, and I get a more accurate result to boot. Then, if I want, I can adjust from there knowing where the baseline should be.

CraigL
 
The quality of the lights has FAR more to do with it than the camera, IMHO.
Oh for sure, but then keep in mind, anything shooting in raw stores white balance data merely as metadata, rather than any sort of affect on the image itself. REDs and Alexas certainly don't have options for you to white balance to grey cards.

And again, with the exposure example, you measured to find the f/4.0 right? That's the first step, then adjust to achieve desired results.
Of course. I'm not suggesting setting up some lights, and then arbitrarily selecting a white balance temp at random. Knowing your lights and knowing your camera are important. Knowing your lights moreso as it will translate across cameras. Or I guess also using a colour temp meter, though I've seen DPs use them more for lights they are unsure of the colour temp and colour shift - ie: a practical.

If you're trying to do a bunch of things on a typical (for me at least) shoot, 5 seconds with a grey card seems like a far better use of my time.
That's exactly my point though. If you're simply the DP, you should know your lights and you should be able to make creative decisions about lighting and exposure and white balance and everything else. If you're Directing/DPing/etc. then that's a different story, but I'm not talking about those situations. I'm also not talking about those starting out.
I'm merely trying to point out that there are times when 'eyeballing it' is perfectly fine, as long as you have the knowledge and experience to make the creative decisions about it. Suggesting that it's 'horeshoes and handgrenades accuracy' is not necessarily correct.
 
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