RED V-RAPTOR [X] 8K VV Lab Test – Dynamic Range and Exposure Latitude

Lab Test

by Gunther MachuMarch 19^th, 2024

At this point, I have to ask: have we entered a new era of global shutter sensors? After our Sony a9 III Lab Test, we now have the new RED V-RAPTOR [X] 8K VV in our CineD lab. Using a new 8K Vista Vision global shutter sensor, we were curious to see how it fares – you, too? Then read on…

Not so long ago, we tested the rolling shutter sensor-based RED V-RAPTOR 8K VV – in case you missed it, you can head to our Lab Test here. It performed very well in our lab and rightfully sits in the top 5 of all cameras we tested so far in terms of dynamic range. Now this model received a sensor update to a new 8K global shutter full-frame sensor. You can read about all the specs and new features here.

Just recently I wrote the following about the new Sony a9 III which also received a new 6K global shutter sensor: “Global shutter sensors have been around for a while, but so far they have been hampered by the fact that dynamic range was significantly lower than what their rolling shutter counterparts showed. RED was the first company that seemed to have cracked this paradigm with their RED KOMODO 6K global shutter camera (see our Lab Test here) which performed very well in our dynamic range testing.”

The Sony a9 III already showed the potential of global shutter sensors by exhibiting the best results any Sony Alpha cam has delivered so far. Will this also be the case for the new RAPTOR [X] 8K VV?

If you are not familiar with how we test dynamic range, I suggest reading this article first. Also, I want to thank my dear colleague Florian who helped me shoot this test.

For obvious reasons, the rolling shutter measurement is missing. Out of curiosity, we checked the sensor using our 300Hz strobe light and as expected, nothing showed, just an evenly lit plane. As it should be!

Dynamic Range of the RED V-RAPTOR [X] 8K VV

To be completely transparent from the beginning: we did not test the new “Extended Highlight” function that is supposed to add 3 additional stops of dynamic range, as it is still in beta mode. It seems to be based on two successive frames (like Z-CAMs for example are offering as well) with a normal and an 8x higher shutter speed image merged into one frame. For moving scenes, this has the potential to show artifacts like ghosting as early footage revealed.

RED does not provide a “native” ISO of the sensor, and in REDCODE RAW ISO can be changed in post. So we used ISO800 as the middle ground to shoot our Xyla21 chart (Firmware version is 1.7). Here is a waveform plot at 8K DCI R3D HQ for 25 frames per second. I have expanded the RGB curves towards 5600K using the white balance slider to demonstrate a RED-specific phenomenon, which is called “highlight recovery”, built as default into the IPP2 color science (REDWideGamutRGB, Log3G10):

About 13 stops can be identified above the noise floor. Just a quick reminder, dynamic range is a ratio, not an absolute number. Hence, if we go from the very left first patch (which is completely clipped), there is a second (white) patch – which has been reconstructed by the built-in “highlight recovery”, but this stop does not contain any chroma information, only luma (no individual RGB values can be seen). Therefore, the first patch containing chroma information is the 3rd patch from the left – this is the first patch where nothing clips. Now from this patch to the next (the 4th, hence the ratio of the 3rd to the 4th) is our first stop, then comes the next stop, and so on. Until we have reached the last stop that still somewhat sticks out of the noise floor – 13 stops. Even a 14th and a hint of a 15th stop can be seen inside the noise floor.

So far, so good. Now let’s have a look at IMATEST:

IMATEST calculates 12.8 stops at a signal-to-noise ratio (SNR) of 2, and 14.5 stops at SNR = 1. This is a really good result but as mentioned, it includes the recovered stop as well.

White balance: just a quick comment, because many readers asked this when we did the last V-RAPTOR 8K VV test – shooting the Xyla chart is independent of the white balance used in camera. We asked our contacts at RED, and the answer was “The camera systems do not use discreet analog sensor gains for different white balances in order to preserve flexibility from the raw sensor data. To further clarify, what this means functionally is that capturing a clip at 2800K, and bringing it to 5600K in post will render the exact same image compared to if you had the camera set to 5600K at the time of capture.”

Also, when we tested the ARRI ALEXA 35, we checked EI400, 1600, and 3200 and IMATEST always showed exactly the same results, as different EI values or ISO’s for that case just move around the code values to higher or lower luma levels. Independent of the EI value, the sensor will clip at a given combination of F-stop of the lens and shutter value.

The RAPTOR [X] shows a similar behavior but is not as consistent across the range of ISO values, as a quick check of ISO6400 revealed: dynamic range drops to 12.2 and 13.7 stops at (SNR = 2 / 1).

Again: so far, so good. Now, let’s have a look at the exposure latitude.

Exposure Latitude of the RED V-RAPTOR [X] 8K VV at ISO800

Latitude is the capability of a camera to retain details and colors when over- or underexposed and pushed back to base exposure. Some time ago, we chose an arbitrary value of 60% luma value (in the waveform) for our subjects’ faces (actually their forehead) in our standard studio scene. This CineD base exposure should help our readers get a reference point for all the cameras tested, regardless of how they distribute the code values and which LOG mode is used.

Again we used 8K DCI 25fps R3D HQ at ISO800, our trusted Zeiss Compact Prime 85mm T1.5, and for your reference here are the development settings in DaVinci Resolve 18.6.5:

I tried two ways to bring the R3D files to the REC709 space:
a) by using a Color Space Transform (CST) from R3D to DaVinci intermediate/wide gamut, adjusting exposure, and then using another CST node to REC709 at the end and b) just adding a node with a LUT (RWG_Log3G10_to_Rec709_BT1886_with_LOW_CONTRAST_and_r_3_Soft_size_33).

Strangely, using the CST at massive underexposure channels started to clip to black. Not so with the LUT approach. So b) was used, and all exposure adjustments were done using the exposure slider in the Camera Raw tab as well as the lift, gamma and gain controls in DVR (on the first node, LUT on the last node).

Here is the base exposure, having my dear colleague Johnnie as a model:

From here, 2 stops of overexposure are possible before the forehead of Johnnie’s skin starts to clip, using the RAW-based traffic light exposure system of the RAPTOR [X] (removing the white sheet of paper quickly). Unfortunately, though, they are not completely accurate, as the below image, brought back to base exposure reveals areas on Johnnie’s head that are already slightly clipping. You can see the highlight recovery at work here – color information is lost, but luma details are still there:

The RGB waveform reveals a bit of a flattened red channel on Johnnie’s forehead. My personal preference here would be to have the option of highlight recovery in post, as is the case with the Blackmagic cameras (when using BRAW). I found it difficult to correctly expose the forehead to be just at the cusp of clipping the red channel. The best way is still an RGB waveform to see where the RGB channels start to align leading to pure white revealing the highlight recovery at work.

Now, from here we start to underexpose by closing the iris of our CP2 lens first and then doubling the shutter value.

At 5 stops below base exposure noise starts to kick in, but it is a very fine noise. 6 stops of underexposure look like this, even without noise reduction quite acceptable:

This looks very good, and we are already at 8 stops of exposure latitude!

Now let’s push it further to 9 stops of latitude, 7 stops below base, and brought back:

Now some noise reduction is needed as the image starts to get corrupted in the shadows. Also a greenish tint starts to appear in the shadow areas:

Nevertheless, I would still rate this as acceptable but reaching its limits. My criterion is always the shadow side of the subject’s face if the skin color can be recovered. You can see in the image above that the shadow side still looks okay-ish.

Now let’s move to 10 stops of exposure latitude. This is the level that the ARRI Alexa Mini LF reached. At 8 stops of underexposure, brought back we get this image:

Noise is all over, but it’s still a rather fine noise. There are no horizontal or vertical lines. Quite impressive! However, a greenish tint is all across the image, as well (also seen in the RGB waveform plot below), and the skin tone on the shadow side of Johnnie’s face cannot be recovered even with heavy temporal and spatial noise reduction:

At this point, I would say, it’s game over. This brings me to the following conclusion: the global shutter sensor-based RED V-RAPTOR [X] 8K VV is capable of a solid 9 stops of exposure latitude, with some room towards 10 stops. This is exactly the result we got from the rolling shutter sensor-based RED V-RAPTOR 8K VV!

The only difference between the two is the fact that the RAPTOR [X] turns greenish in underexposed areas, whereas the V-RAPTOR VV turns pinkish in underexposed areas.

Comparing it to the recently tested Sony A9 III which is also capable of 9 stops of exposure latitude with its 6K global shutter sensor, the 8K V-RAPTOR [X] exhibits a similar latitude but shows color drifts to green. However, the richness of colors is better with REDCODE RAW as colors quickly lose saturation in underexposed areas with the Sony A9 III.

The full-frame ARRI ALEXA Mini LF is capable of one more stop of exposure latitude (5 over to 5 under), and the king of the CineD Lab Test is the S35 sensor-based ARRI 35 which exhibited 12 stops of exposure latitude.

Summary

The global shutter sensor V-RAPTOR [X] shows a really solid result in our Lab Test. Compared to the previous rolling shutter sensor-based V-RAPTOR 8K VV it proves the point (again) that recent global shutter sensors are not hampered anymore by any loss of dynamic range, and have the huge advantage of eliminating any image skew due to rolling shutter effects.

More than impressive!

What do you think about this new model and the results from our test? Have you shot already with the RED RAPTOR [X]? Let us know in the comments below.