Matching two Z7U's - white balance problem?
 

Just a quick note to see if others with two or more Z7U's (or other similar Sony cameras) have had issues getting shots to match between cameras.

I have noticed that there is typically a 200 - 400k difference between my two cameras (according to the numbers I get when white balancing on a 100 IRE white card).

When I white balance BOTH Z7U's, the shots will look very closely matched (even though there is a 200K difference between what the two cameras report). If I manually dial in the same number for each cam, the shot looks way off - one camera looks way more red - the other more towards the blue end.

Note: To test to the cameras I reset the units to factory defaults, and then loaded in the same camera profile to both Z7U's. I did tests for the pic profile I like the best -- and did tests also with pic profile set to OFF. The white balance is off regardless of these settings.

I have attached two pics. The first shows what both cameras achieve when white balancing manually. The second shots shows how differently the cameras see color when auto white balance is set to ON.

If anybody has looked at how their two cameras "match", I'd appreciate your feedback.

Thanks!

Ian

you could use the preset 56k or 32k.

Using the default 5600k or 3200k (outdoor / indoor) presets, the images don't match. The only way to get close is to do a proper white balance. It would be nice if the factory had set up the same camera models to match -- or to offer something somewhat closer.

Ian

Just out of curiosity, are the picture profiles on the same setting?

I use a Z7e and S270 together, and take a white balance on one then manually set the same degree kelvin on the other and they match. I've set both camera on PP4 and ensured all the settings in the profiles are identical.

Same here, both my Z7 and S270 are perfectly matchable when doing a manual white balance setup. You have to pay very close attention though to the light that illuminates the white card: slight changes in light colour occur invisibly for the human eye, but the camera will measure the difference and adjust the white balance accordingly. Especially in daylight, light temperature can differ quite a bit from one minute to the other...

Hi, Rob . . .

Both cameras for the pics shown here were on the same pic profile. In fact, as I mentioned, I completely restored all of the settings for both cameras back to factory default, and then loaded in the same camera profile to both Z7U's before running these tests. I've done this same test with no pic profile selected and with the same pic profiles selected -- and the results are similar. Also, both cameras were set up for these tests side by side -- and both cameras were balanced at the exact same moment. Again, pic. #8 is manual white balance with white card to both units. It looks okay to me. Pic. #11 is what the can "sees" when in full auto white balance.

As for the suggestion to white balance one camera, and then dial in the K temp (number) to the second camera doesn't give a good balance. However, doing a white balance for both units in the same light does work -- even though the cameras report numbers 200K to 400K difference. The weird thing is that if I white balance with the camera that gets the higher number, I can't simply dial in a number 200K, etc. lower on the other camera and get a good look.

I am attaching here another pic: In this shot each camera was set manually to 6800K. The L. cam makes the brick considerably whiter -- while the R. cam makes the brick more "creamy" looking.

Can such a color variance be considered "within spec" for this kind of camera?

If anyone can take their camera to run a test, that would be awesome.

Thanks again!

Ian

With 2 identical VX2100's, I always had major issues making their WB look anywhere close to the same. Later with 2 identical V1's, I could get a great match without any special manipulation. I just assumed that Sony was improving their products. Unfortunately, I don't have access to another Z7 or even a Z5 I can compared with directly. But it doesn't surprise me that there is a little difference between your 2 - Z7 camcorders. I too would wonder if 200 - 400K is an acceptable production variation. My guess is that it is. Does the F-stop match on both cameras?

I filmed my home-made test chart with the Z7 and the S270, both in exactly the same conditions and at the same moment. This is the result. Not so far off, but certainly not equal either...
I put both slightly out of focus to prevent moiré, if any, of influencing the colour rendition. The warmer image comes from the S270.

Of course we mustn't forget that we are looking at still pictures here, and that in a movie details such as minor colour differences tend to loose importance, as long as familiar tints such as skin tones are staying within an acceptable range of fidelity.

Hi Luc is the S270 still loaded with my settings? I think it has been set up to be similar to the BBC spec on my HPX301.

Greg, the f-stop between the two cameras are the same. If I put both in auto iris (which I don't usually do) both Z7U's place the scene at the same (or sometimes very close) stop.

Luc, thanks so much for doing a test between your two cameras. Was the test done with a white card? Or is this test showing what you get when shooting with auto white balance ON?
Your results look similar to mine. I notice that the whites are off from one unit to the other. The whites in one pic look white, while the other image leans toward yellow ... at least that's how it looks on my monitor.

Thanks again!

Ian

Hi Gary. I have left he two picture profiles with 'user' denomiation on the S270 unchanged and I use number 1 of these when filming, but for this test I have set both camera's to the preset picture profile number '5' which is called 'film look 1'. Just in order to have the same preset.

Surprising side effect of the test: although I arranged to have the distance between the front lenses of both cams and the chart exactly the same, the distance reading on the display was off 1 foot (30 centimeters in my case).

Hi Ian,

for the test, white balance was manually set on both camera's with a white card with 100 IRE white reference, and adjusted together on the same card under the same ligthing conditions (daylight, shade). As you say, the main difference is in the yellow tones. As a still photographer, in Photoshop I would correct this by adding blue or subtracting yellow on the screengrab with the yellowish white. Now thinking about it: to match the two Sony's, using one warm-card and one white IRE card for the white balance setting could possibly do the job, as the cards are blue-ish! If I find time, I'll give it a try.

Hi, Luc . . .

Thanks again for your test and your input. If you white balance with a warm card for one camera and a 100IRE white to the other, it would be interesting to see what you get. Please let me know how it works out.

I am disappointed that Sony hasn't been able to match both my Z7U's better. I noticed this some time ago, but I only started to think about a possible white balance discrepancy after someone I know with four Z7U's wasn't happy that one of his four units didn't have the same color characteristics as the other three. He, I guess, was lucky to get three "good" ones.

Is it worth having Sony have a look? I wonder if they could set up both your units to match?

Ian