Never knew I wanted to know this, but now I know it and I am forever grateful.

I will use this information for more accurately describing the shame I feel when using a mix of window lighting, an LED panel and tungsten bulbs as my "trio of confusion key lights" for my super accurate colour science comparison videos. Shame level 97+.

Hey Gerald, thank you very much for this video. My name is Tony Esposito, I am the Co-Chair of the IES Color Committee that developed and maintains TM-30. Thank you for your discussion of TM-30. I wanted to provide some additional information for you and your audience if you don't mind: - Color fidelity measures, like CRI and Rf, are not measures of "accuracy", but instead how SIMILAR (i.e., how close in color space) your light source renders color compared to a standardized reference source at the same CCT. Depending on the CCT of your light source, that reference source will be a Planckian Radiation, a mathematical model of daylight, or a blend of the two. - Rg of 100 is not "spot on" unless your Rf is 100. With an Rg of 100 and an Rf less than 100, some colors will be oversaturated and some will be undersaturated. - As a matter of clarity, describing Rg of 100 as "spot on" implies that an Rg of 100 is always the desirable target. This isn't true. Research shows that people tend to light color with an increase in saturation, so sometimes an Rg greater than 100 is warranted. Keep in mind that most commercial light sources desaturate red colors, which people tend to dislike. Edit: you later describe Rg 100 as being the ideal, again, which isn't exactly right. People tend to prefer an increase in saturation, especially in red. - The last number in the year is indeed the year. TM-30-15 was published in 2015 and TM-30-18 was published in 2018. There was a big change to Rf--the scaling factor was changed--between these two versions. TM-30-15 Rf will be incorrect. Any version of TM-30 after 2015 is good. - For finding spectral matches, SSI is only really useful when it is very high, because when it is low is doesn't help you understand "how" the SPDs are different. That's why you need to compare the SPD's visually. Importantly, not all differences are created the same (for the purpose of creating a visual match), which SSI also doesn't tell you. If a spectral match is desired, the best course of action is to find two sources with the same CCT and with very high color fidelity (or SSI). Overall, my point is that for the purpose of matching SPDs, I don't see SSI being significantly more useful than Rf because you still need to visually compare SPDs when SSI isn't very high.

As others have said endlessly, "You are the camera warrior we all sought for, and really needed." 🥺 You have my many thanks Gerald. 😎👌

You had me at "Today we’re gonna get pretty nerdy"

I’m Gerald Undone and I’m not the one to gossip, but your CRI can’t beat his SSI.

If even Gerald is calling a video topic nerdy, you know we’re in for quite the video.

I'm hyped you are getting sponsors to pay you money, and am hyped you are so upfront about the relationship with them. Keep it up. Always the most informative videos...

I'm Gerald Undone and all your base are belong to us. Here for the nerdy stuff. Thanks Gerald!

Hey Gerald. I was studying on one of the best film universities around the world (FAMU, Prague) and I truly wish I had a teacher like you for the technical stuff. You have a great talent to explain things which oftenly are boring. With your special sence of humor and speech quality its always a pleasure to educate myself.. You should definitely consider a career outside of YT on a film university. Thanks a lot for the job you do ♥

"today we're going get pretty nerdy" *Gets popcorn, Coffee and a notepad! LETS DO THIS! :)

The most i’ve learned about lights on KZfaq. Thank You.

Super interesting - thanks Gerald!

Finally got a chance to watch this. Excellent explanation of all the metrics for the general user. TM-30 is one of my personal favorites too, but I think it's a little too convoluted to become a standard for people who aren't as nerdy about lights. I always look at SSI first, then extended CRI along with the individual R-Values to see if there's a specific deficiency in a light. 99% of the time, good CRI/R-Values= excellent SSI. As much hate as CRI gets, you are right in that the main problem is with how it is used in marketing, because if you know all the individual extended values, it's still very useful. It's also important to look at the CCT Vs. the advertised specs, and maybe more importantly, the green/magenta tint. With almost every light I test, too much tint shift is the deal breaker, and overall, the vast majority of lights sold now are very good compared to just a few years ago. The last thing I'll say is that I think with how good lights have become, people are scared to buy lights that score slightly lower when they shouldn't be, because you have to keep in mind that modifiers will significantly change the readings of a light, and most people use them. Like my key light set to 5500K and bare bulb is a little green, but with diffusion it's closer to 5050K and a little magenta. I've seen stock reflectors change the CCT of a light by almost 1000K. All of these numbers change when you go from 1-100% brightness as well. Lights change as they age, get hot, stay on for long periods... lots of smaller variables that separate quality lights from cheap ones, even if the cheap ones "score" well. I want to keep typing, so perhaps it's time to make my own video...

The kids are luucky to have you Gerald.. I know most of this from sweat and tears in stuudios, on sets and locations, over years, and with my ownskewey notes. This is great, well done and to the kids -say thanks.

Great stuff as always. Thx for the work you put into this! You helped me elevate my video quality beyond many bigger channels. I have studied so many of your videos lol. Thanks again my man!

Wow this was so useful and informative man! Always loved to know more about light characteristics, Thanks so much for sharing!

Another KZfaqr, Justin Phillip, did a video on this device. However, he talked about how he used it to overcome his colour blindness when working as a cinematographer.

Videos like this made me a fan of your channel. I have literally waited for your next nerdy explanations for a long time now. Thanks for doing this, Gerald. I appreciate this so much!

Many thanks Gerald, for clarifying the various methods of measuring the colour of lights.

Love your videos, they're a perfect balance between informative and entertaining. I wish I had found out about your channel sooner.

Another masterful deep-dive! Explained it so well. 🙌🏼

Near the end of this video I held my head in confusion thinking, "Why am I actually understanding this?!" Props to being a great educator Gerald and thank you for your knowledge.

What a great way to kick off my Friday. Catching a fresh Gerald Undone video

Pretty nerdy indeed but this was actually incredibly exciting to watch!

I don't think my Inner Nerd could be happier right now. I have added the Sekonic C-800 to my shopping list. Thanks for another super in-depth video covering a powerful tool in the Sekonic, and a film school level explanation of the accuracy of film lights.

Great video! It's a dense, hard-to-grasp field, and you did a great job explaining and translating some pretty difficult items into a "what you really need to know" format.

oh shit im early for a gerald undone video "I'm Gerald Undone and my face outputs 9 stops of light"

WOAH!! This was so helpful. I'm gonna be referring to this when buying new lights and doing reviews in future. I'll also have to link to this video too if that's ok :D That Sekonic is an amazing tool, too. Thanks Gerald.

When I want to actually be smarter about being a videographer and KZfaqr, I watch Gerald. I'm a simple man. He posts, I watch.

Your the man Gerald. Very, very useful information. I own many lights and was thinking about investing in the Sekonic to determine which ones to keep versus unload. I love to get "UNDONE"! GREAT CHANNEL!!!!!!

This video was more useful than basically any film school class I ever went to

Mind blown. Thanks, Gerald. Very interesting.

Your videos ALWAYS teach me so much! Thanks Gerald

Thanks! It was sort of like getting a tooth pulled, but only because I need to do it, and I have never been great on this subject (camera's, lighting, etc.). I've always struggled to understand it, and you helped quite a bit actually. Glad I'm subscribed to you Gerald.

loved it! Thank you! Finally someone who explains all this in a timely manner. I never managed to find a good explanation of all the metrics and methods of evaluation of a light, until now

And that's the way you do paid add. Interesting, informative, and well done! Thanks, Mr. Undone!

Extremely useful! Thank you Gerald!

Omg this is fresh😍..Gerald you nerd!!this is gold

loved it, as usual. Super interesting thanks Gerald!

Excellent and deeply nerdy as always! Loved the detail 👍🏻😊

I learned a ton! This is awesome information, thank you for making this video. You were very technical and yet I understood everything you said. You have a way with words that just clicks for me. Have a good one!

If you're interested, ANSI/IES TM-30 rev 20 is out, and is actually freely available for anyone to download and read

SSI is one of the reasons that I appreciate Curtis Judd's light reviews so much.

Thanks for this video, your description is clear and easy to understand while being very informative. I just find light measurements so fascinating, I think I'll have to start saving up for the Sekonic for my channel. I review flashlights which aren't designed for the same purpose as video lights, so I am very interested in testing them to see how they how they perform according to these metrics. Thanks again for always producing fantastic content! You've helped a lot with my journey to producing better videos

What an amazing video, learned alot for real. I run a fine art printing shop specializing on reproducing paintings and this is a great help when getting new LED ambient lights for the studio. Big Thanks!

Amazing Video! You've helped me a lot. Thank you.

Very very interesting and informative. Thank you!

I just love your videos. You can explain complex things with such ease and clarity

Thank you professor Undone, I learn more from you than in college.

Indeed, it's a very informative and helpful guide. Thank you

Thank you so much for making this!

Great explanation of the color metrics, especially SSI as it has more practical "in the field" applications to match various light sources. One clarification on the CRI metric: it's the rendering of the first 8 colors compared to incandescent (not daylight) So the conventional incandescent light bulb has an "ideal" CRI of 100.

Super helpful, thanks for helping me understand my color meter better.

I was mildly interested but I ended up learning something new and liking the video. Well done

mind blown. so much good content on your channel. i really love the one about codecs too.

This is some amazing information that no one in Film KZfaq ever talks about. Learned so much. Thank you. 🙏

I'm already subscribed, and I liked the video, but I still rewatched the video at 75% playback speed, just for additional entertainment. 😉🤣 Thanks for being awesome, Gerald!

Thank you so much ! You have managed to make sense of these cryptic lighting industry terms. This new found knowledge will allow me to make a more discerning buying decision. This is just the sort of facts that we as photography enthusiasts need at our fingertips. Well done !

Practical info, and great for sharing w colleagues. Thanks for putting this together

This video makes me appreciate the automatic setting on my camera.

The way your lighting your hair is amazing!

Very interesting to dig into the different lighting terms. Are there any sekonic (or other) color meters you'd recommend if you only want to measure SSI? The C-800 seems like the best of the best, however, I wouldn't use 95% of its features while shooting video. Thanks for the video!

Nice Video Gerald 🔥

Damnit Gerald! You've done it again, killer job.

Just in time! I wanted a tool to measure light quality and here you are!

As always, very nurdy interesting important information. Thanks!🙏❤️

Dammit. Now I need one. Excellent video, Gerald.

Great explanation. One of those moments that you realize a passionate KZfaqr does a better job than your university teachers explaining something. . Congrats

A very important video. I often have trouble with LED lights with holes in their spectrum. Pity colour spectrum meters are so expensive...

Thanks Gerald… I was just looking for a video on this topic.

Very informative video, thanks Gerald!

Great video Gerald... never stop getting nerdy

Fantastic Video! Been considering one of these Sekonics and I think this has just pushed me over the edge! Top job!

This is great! Thank you Gerald!

The C-800 is an awesome tool :) Been using it in my LUT building to ensure lighting quality and it really helps! Great tutorial :)

Thanks! I knew CRI wasn't the best (or at least the most fair) metric, but this helps a lot in understanding the measurements and different methods. Also a nice little demo of the Sekonic. I'd love to have one, but that's way out of my league for now..

"today we're gonna get pretty nerdy" dude ALL your videos are nerdy

This a very cool unit, thanks for nerding out on it ✊ Sometimes even Skypanels don't match panel to panel. The have Direct or Colour calibrated modes to help when working with multiple units.

Greetings Gerald. That's it. edit - actually no. That video was really cool. Thank you. I didn't expect to find that so useful.

Very cool video, thank you for breaking it down!

I'm now an expert on lighting. 🤝🏽🤓 😂 very impressive, the amount of information you were able to convey in an understandable way!

Of course you post this after I JUST bought a set of video lights 😭😭

Love those type of nerdy videos ! I don't understand a thing but I feel more smart at the end :D lol

Thanks for sharing your knowledge with us! I’m definitely going to put this to use

Gerald is a mindreader, I was about to buy lights

You know it's going to be a good video when Gerald prefaces it with "today we're going to get pretty nerdy."

Great video, very nice to know how this tool help you out match the color of the lights not only RGB but also Bicolor to match the temps. 👍💯

Excellent review and education. Love it.

I'm Gerald Undone, and I'm not far sighted, I just have a long minimum focusing distance

Gerald „this one is nerdy“…. me „oh boy, do I have to learn a lot…“ 😂

This is great Gerald! Thanks for it. You could make one talking about LUMENS, LUX, CANDLES differences how to calculate them, the stops of light and how to calculate them, etc

One little thing at 7:28 ... color temp is NOT the temp of the glowing tungsten probe. Actually it represents the temp of a black body radiator which generates an according light spectrum at this specific thermal temp. This sometimes gets mixed up with the temp of a glowing tungsten probe because it is not that far off. But tungsten melds at 3695K. So it wouldn’t be a good measurement for daylight. Just to get even a little bit nerdier. Great video non the less. ;-)

I’ve been wanting to get this one for a while now. Love the idea of this device

Your video is fantastic. Information that is both helpful and unknown. I'm just surprised as to why you didn't turn out all the lights and perform the test properly.

Most probably will never use this info but good video and explanation Mr Gerald.

This is the Comicon of nerdy lighting science videos and I'm just the dude that is a casual fan that saw Avengers one time and is nodding along like I know what's happening.

Awesome video! Thanks a lot!

Lily useful video, thanks for the info.

Many thanks. Inspiring video.