Thoughts about WB calibration across different cameras

[Ty Harper]

Hey all,

Based on your individual experiences, how would you get accurate WB/Color Match across cameras if you had an R5C shooting in Clog 3 (which has the same quick custom WB button as the C300s etc), a 1DC shooting in original CLog, a 5D MK III using Magic Lantern, a Sekonic C-800 color meter (which I got for really cheap at an auction a while back), an X-rite color checker and a grey card?

To be clear, I know how to WB with all these tools and color matching has been totally fine using Resolve - just curious how others might approach it with the aforementioned tools?

Thanks in advance!

[tupp]

If you are doing a multi-camera shoot, first put the grey/white card and color chart together, lit by the dominant full-spectrum light source of the scene/event.  Flag other light sources from hitting card and chart.  To avoid glare, the light source should be at about 45 degrees (or less) to the plane formed by the card and chart.

Position all the cameras side-by-side as close as possible to each other, about 6-8 feet directly in front of the card and chart, and perform a custom white balance on each camera.

Then, record about five seconds of footage of the card and chart with each camera.

If the dominant light source of the scene/event is intentionally not full-spectrum, perform the above procedure using a separate full spectrum source with a color balance that is close to color of the dominant source of the event/scene.

If you are shooting at separate times/locations with each camera (not a multi-camera session), do the same procedure above at each time/location with the one camera.

Of course, if you are shooting raw, the white balance will not affect the captured image, but having a custom white balance should provide a decent starting point for your NLE and for color grading software.  The footage of the charts will help in more finely "dialing-in" the color correction in post.

 

[Ty Harper]

@tupp thanks for the perspective. I've been in talking head interview scenarios where the lighting is a mix of LEDs and natural light in a space with big windows south and east facing. And so I've been setting up lights and cameras first, and then been using the Sekonic C-800 to:

(i) get an initial read of the color temp of the natural light hitting the grey card and color checker located in the central area that the talent will be sitting (it's a lot of natural light so not at all too low) and using that as my base color temp reading.

(ii) get my bicolor Litepanel Astras as close to that natural light base reading as possible using the C-800's multi-light color match function and manually tweaking each LED.

(iii) I then get the overall LED lighting levels roughly set with respect to recommended IRE levels for each cam via my monitor.

(iv) calibrate WB of each camera individually

Now here's my question. At this point should I calibrate each camera using their individual custom WB functions or by inputting the initial base temp I got via the Sekonic C-800?

I ask because I've gone the route of calibrating WB using each cameras custom WB and noticed that in the case of the R5C (which actually displays the color temp reading) that the color temp reading is way off from the Sekonic C-800 base reading. And while I know the WB calibrations from each camera will be off from each other to some degree - I wonder whether using the base color temp of the C-800 will result in the cams being off by the least degrees.

Hope this makes sense.

At the end of the day it's not like I've had to struggle much to match colors for my needs - but it would be good to know which approaches might give the best results.

[tupp]

2 hours ago, Ty Harper said:

... should I calibrate each camera using their individual custom WB functions or by inputting the initial base temp I got via the Sekonic C-800?  ... And while I know the WB calibrations from each camera will be off from each other to some degree - I wonder whether using the base color temp of the C-800 will result in the cams being off by the least degrees.

I don't know which method is more "accurate"  in matching the cameras to the reading on your meter or in matching the cameras to each other.  I would guess that the difference is minor, but it would be interesting to see a comparison of  the two methods.

I know that merely using the custom white balance on each camera without a color meter will get a close enough color temp match, and it is quick, easy and consistent.  Either way, you will still be tweaking sliders (or clicking eyedroppers) in post to get the final correction.

By the way, it is generally a good idea to avoid mixing light sources of different colors on the same side of the subject, especially on a person's face.

Also, you might try leaving a slight difference between the color temperature of the exterior light and that of the interior lights.  I usually keep the interior key light neutral.  If a window is visible in frame and if only skylight is streaming through it, I tend to keep it around 1/4 CTB -1/2 CTB from neutral.  If direct sunlight is visible in the background, I sometimes keep it at neutral -1/4 CTO.

[kye]

On 10/15/2022 at 9:49 PM, Ty Harper said:

Hey all,

Based on your individual experiences, how would you get accurate WB/Color Match across cameras if you had an R5C shooting in Clog 3 (which has the same quick custom WB button as the C300s etc), a 1DC shooting in original CLog, a 5D MK III using Magic Lantern, a Sekonic C-800 color meter (which I got for really cheap at an auction a while back), an X-rite color checker and a grey card?

To be clear, I know how to WB with all these tools and color matching has been totally fine using Resolve - just curious how others might approach it with the aforementioned tools?

Thanks in advance!

I've noticed that in all the cinema camera comparisons on YT there are significant WB differences between cameras, regardless of if they say they "set all the cameras to 5600K" or if they said they did a custom WB.  Some of these differences are quite significant actually - so much so that they render the comparison pretty much meaningless.  These are across enough DPs that I don't think it's user error.

I would suggest that in addition to the custom WB on each camera, I'd get full-spectrum shots of the colour chart to use as a reference in post.

In post I'd suggest using ACES or RCM to colour-manage your workflow, and test your conversions with the colour chart to see how closely your settings get the two cameras.

The reason that I suggest this method is that there may be differences between how your colour pipeline handles the two LOG profiles, even though both cameras are the same brand, so any differences should be minimised.

I'd be comparing the two shots confirming that the greys are neutral, but also that the primaries are all similar hues (ie, no hue rotation), the same luminance, and also the same level of saturation.  The more colour swatches you have on the colour checker the better so you can tell if there are any non-linear differences that might need tweaking.

Beyond that, unless you're doing a multi-cam with similar angles, you just need to match the cameras in post so that the footage from both looks like "they're both from the same universe".  People are very forgiving when it comes to noticing colour shifts (unless your content is boring or they're very interested in cameras) - if you look at older movies shot on film there were often large colour differences and those didn't send people running from the theatre etc.

[Ty Harper]

1 hour ago, kye said:

I've noticed that in all the cinema camera comparisons on YT there are significant WB differences between cameras, regardless of if they say they "set all the cameras to 5600K" or if they said they did a custom WB.  Some of these differences are quite significant actually - so much so that they render the comparison pretty much meaningless.  These are across enough DPs that I don't think it's user error.

Thanks for this! And yeah that's essentially what I'm getting at, and while my current workflow works fine for my hobbyist needs, I was just curious how others might approach my scenario - and to your point - whether there might be more color discreprency across cameras using the custom WB method vs dialing in the exact same color temp for each cam. 

Thinking about it now, my instincts are leaning to dialing in the same color temp across cams as the approach that probably gets your cams closest in color temp.

[kye]

51 minutes ago, Ty Harper said:

Thanks for this! And yeah that's essentially what I'm getting at, and while my current workflow works fine for my hobbyist needs, I was just curious how others might approach my scenario - and to your point - whether there might be more color discreprency across cameras using the custom WB method vs dialing in the exact same color temp for each cam. 

Thinking about it now, my instincts are leaning to dialing in the same color temp across cams as the approach that probably gets your cams closest in color temp.

I am not sure which WB approach would generate the best match, or even if the WB differences I've seen in comparisons are due to the WB of the camera or just how the cameras were all treated in post.

All the more reason to do your own tests I guess.  Considering you own both cameras, I'd suggest you film both (match WB settings and also do a custom WB) and then play with the post workflow and see which overall approach is best.

I'm curious to hear what you find 🙂