Today we are going to look at the differences between Rosco’s CTO and CTS gels. CTO has more of a reddish orange color, and CTS is more yellowish green. For skin tones, I prefer CTS because it makes skin tones look more alive. With CTO, I feel like your character gets too red and turns into what I like to call, a “pumpkin head,” but let’s take a look at all the different types of CTO and CTS to see their unique qualities. First, here are some charts from Rosco about their CTO and CTS gels:
You can really see here that CTS has more of a yellowish green feel, and CTO has more of an orange red color.
To really see the unique qualities and differences between these two types of gels, we tested each CTO and CTS gel with our beautiful model Monette. Before adding any gels, here are the color temperatures we have for our barebones setup:
Camera Lens: Set at a T2.8
- 3200 K on key side of face, light meter reading: T4 (+1 stop from camera)
- 3600 K on fill light, light meter reading: T1.4 (-3 stops from camera)
- 2100 K on backlight, light meter reading: T2 (-1 stop from camera)
Below is the top down of what we have set up as well:
Let’s take a look at how each gel compares to our setup without gels, and then after that, we can go into comparing the gels with one another. For now, let’s take a look at how each type compares to our original setup with no gels, starting with a table showing our readings:
With 1/2 CTO, we lose about 2/10 stops of light, and our color temperature warms up 300 K from 3200 K to 2900 K.
To my eye, the 1/8 CTS already looks more yellow than 1/8 CTO. However, the amount of light lost is the same for both of these gels. we lose 2/10 of a stop of light. The CTS is slightly cooler, but by only a 100 K difference.
With 1/4 CTO I lose 3/10 of a stop of light and about 400 K.
The 1/4 CTS makes us lose slightly more light than the 1/4 CTO. We lose 4/10 of a stop so there’s about a 1/10 stop difference. The color temperature is about the same as 1/4 CTO. Around 1/4 CTS, it’s starting to look like there is enough nice color separation to pull her from the background. She’s starting to stand out more, starting with the 1/4 CTS.
So looking at 1/2 CTO and 1/2 CTS, let’s take a look at how she looks, starting with 1/2 CTO. Right now even to my eye, the 1/2 CTO really makes her have a red tonality. With the 1/8 and 1/4 CTO, there was more subtle red, but with the 1/2 CTO, you can really see this color, and I wouldn’t go this far with the CTO. This amount of red distracts me from the scene, and we lose 1 1/2 stops of light with the 1/2 CTO, while warming up by 800 K.
Now let’s took a look at 1/2 CTS and see how it compares to 1/2 CTO:
With 1/2 CTS, we lose the same amount of light, a stop and a half, and there is the exact same amount of Kelvin. However, CTS is powerful because the yellow green tonality warms up the image without distracting us like the CTO. The CTO is more reddish orange, which is more distracting to the eye.
Now moving on to full CTO:
With full CTO, we’ve lost about a stop of light, and wow, she looks really red orange! We dropped 1200 K, and now we’re down to 1900 K. As I said before, this amount of red orange tonality is distracting and takes me out of the scene. With full CTS, she still is being pulled too much from the background, but not as much. We also lose a little less light, instead of a full stop, we are losing 7/10 of a stop, and now with the full CTS we are at 2100 K. Full CTS is a bit cooler and takes out just a bit less light.
Now check out the side by side screengrabs below of the gels compared to each other, so you can further see the unique qualities of each gel.
Comparing the Gels to Each Other:
In conclusion, the full CTS and full CTO make it seem like Monette is lit by another source, so I wouldn’t go that far, and around a 1/2, the gels start to make her pop more from the background. With the 1/8 and 1/4 gels, there are more subtle difference. However, overall CTS falls better within my lighting style and color palette. The CTO is too reddish orange and creates what I like to call “pumpkin head” that is both unnatural and takes me out of the scene. To me, the yellow green tonality of CTS looks less distracting and more natural, but for some of you, maybe you’re going for more of a reddish color tonality of the CTO, and that’s ok. Now that you’ve seen the side by side comparisons, go out there and choose the right gel that works for what you envision.