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Matching 900r's


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#1 Stephen Price

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Posted 01 May 2008 - 03:59 PM

Does anyone else experience extreme differences in colours between two
Sony 900r's?

These cameras seem to all have a green hue, but i find two 900's up against each other with the same colour temperature, look different. How do others people match multi cameras on set? I find i have to constantly tweek one cameras colour temperature to stay matched with the other. Is this common and how do others deal with it?

Thanks
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#2 Mike Williamson

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Posted 01 May 2008 - 05:38 PM

I recently did a shoot with two F900/3's from Panavision where I planned on doing a white balance offset towards cyan for the look of the show. I white balanced both cameras on the same white board lit with some CTO and Minus Green gels, and then I checked (I think) the "Levels" menu. In the menu, it gives you a numerical read out of the level in each channel based on the white balance you've done. Unfortunately, the two cameras did not match numerically. So, my guess was that picking one white balance offset and changing the other camera to match it numerically would be my best bet, as I trusted that more than I trusted the consistency of the auto white balance function. It seemed to work pretty well, and from the little bit of the footage that I've seen in post, the cameras match.
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#3 Walter Graff

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Posted 01 May 2008 - 09:18 PM

There is far more to matching cameras than just white balance. White balance is the end result of registration. If flares, gammas, peds, or any other element that make up a properly registered camera is not the same, it will end up being a different picture. And the numeric numbers in a camera menu do not mean much in terms of exactness. -5 on one may not be the same -5 on another art because of slight variations in production runs and/or setting being different in each camera that make one reading look different on one camera than another. Part of that is registration, and part tolerances from production. Get yourself an engineer to set up the cameras properly (it is referred to as matching cameras), ask your rental house to do it, or learn to do it yourself. You need a 14 step chip chart, and scope and knowledge of how to set up camera elements that make them match.
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#4 Mike Williamson

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Posted 01 May 2008 - 11:12 PM

Yes, obviously you'd want all the settings to match, I guess I'm taking it forgranted that you'd match them up numerically as well in terms of whatever settings you're entering into the cameras.

But yes, Walter is correct that you'll get the highest level of accuracy either having an engineer match the cameras or doing it yourself using scopes and a chip chart. The numeric values are completely arbitrary and don't take into account the mismatches in the sensors. In my specific case, I assumed correctly that the cameras were fairly closely matched to start with and that any slight mismatching could be fixed in color correction.
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#5 Stephen Price

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Posted 02 May 2008 - 02:27 AM

I have found these cameras to drift, same lighting situation, but over time the cameras will begin to look different, usually one more green than the other. In your experience, is it common to constantly adjust menu page settings, using waveform and vectorscope and chip chart to achieve a match picture? Is this practical on set? Is it often done?
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#6 Mike Williamson

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Posted 02 May 2008 - 03:56 AM

I was shooting from about 60 to 70+ setups a day, which would not have left a lot of time for camera balancing on set. I think that if you're going to have a reasonable color correction session, then your time on set can be better spent.

In terms of balancing to a chip chart using scopes, this is something that you'd want to do in a controlled setting during camera prep. Besides losing time, the number of variables in what you're looking at on set would be way too broad to look at on scopes and make sense of, at least for me. Or you'd be trying to recreate an extremely controlled testing setup in the middle of your set, which would be an uphill battle to put it mildly.

But I shoot HD the same way I shoot film, where I tweak the cameras during prep and then leave the settings alone except for simple white balance changes. I'm sure some DP's would have their DIT make a lot of tweaks in the field, not sure if that approach is more common. I've heard that Michael Mann and Robert Rodriguez work that way.
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#7 Walter Graff

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Posted 02 May 2008 - 06:11 AM

The common way of setting up cameras is to set them up prior to shooting. This is why Mann et al that were mentioned do it. It is standard operating procedure, not something only the 'big guys' do. Cameras drift. All cameras. They will not drift during a days worth fo shooting but will over time and use. Someone asked how often do they need to be set up? The answer is far more than folks do these days. In the days of older cameras we would not go out without fine tuning a camera on a chart before shooting. That is because registration is physical, not electronic. Then came more solid state cameras and suddenly folks got the incorrect notion that you don't need to do anything but shoot. Registration is still physical even in today's solid state cameras. But them being solid state they drift far less than cameras of years past, but they still have issues over time. And if you are playing around inside a camera with settings you are affecting everything in that camera and how well it sees. So my answer is how I shoot. I set up my camera to the way I want it to look overall first, prior to shooting. Then in the course of the shoot day there should be nothing I need to do to it other than white balance to maintain that look. If you rent, then you must make sure the rental house registers the camera, or you do, as rental houses have cameras that folks play with when they rent so they can have all sorts of looks different from other cameras. Too many people play with the engineering menus of a camera with little knowledge of what they are doing or the consequences. That is why it is an extra step to get into them and why the other set of menus is correctly called operator menus an easy to get into.
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#8 tylerhawes

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Posted 02 May 2008 - 03:34 PM

If you're shooting F900s and want to get something great out of them, you really need a DIT to help you.

Also, you only have to get them to approximately match, and then you can easily take care of the more subtle matching in post. F900 will need a good amount of color in post anyway to make it cinematic.
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