Lux and Lumens Explained: How They Can Help and Hurt When Buying Lights

Lumens and Lux have started showing up in the specs for video as well as commercial lights, but what are they and how can you use them? Frank explains the difference between Lux, Lumens and Foot Candles, how to convert them, and which specs are helpful and which aren’t when you're purchasing or renting lights for your video production.
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[@MattDoesSound]

I tried watching some videos about this topic and the first minute of this video is a perfect summary of what they were like.

[@PullMyFocus]

It's crazy, right? It is a tough topic to understand let alone convey. I have to review it every now and then.

[@bqgin]

I was blown away by the quality of this video espacially seeing subscriber count. Definitly deserve more.

[@lindahaley9384]

Lol! Very funny and very true. At first I figured this is another lux lumen video where I will have no idea what their saying or of topic. I was relieved to find the into as a joke, and elated to say that I finally have got the true understanding that I was seeking...look no further people. Very Very Very funny into, I think you guys may be sitting on a comedy show career also🤣🤣

[@collierlandry]

As a working Director of Photography, this is the best, simplest video breakdown I have ever seen....Bravo and well done gentlemen, big fan! Subscribed!

[@onm9128]

Oh wow! This was super helpful in just a click. You got my like all the way, man!

[@ejikeonwunabonze]

Hahaha! the first 1:30 seconds I was like, what is he talking about? Nice one guys. Very useful.

[@kev_mclernon_family_channe4745]

Awesome!! thank you especially for explaining in terms i can understand, Bravo!

[@saiKiran-sg9ko]

Man I've been trying to understand this for over three days as of now and this video pops up in front(probably Google recommend) and Wham! Thanks a lot. Very much helpful.

[@PullMyFocus]

Glad it was helpful and thanks for the kind words.

[@roydominicmacasero4597]

am buying a desk lamp (overkill) but this helped me understand the specs I was looking at. Thanks!

[@765934]

Much thanks. Well done.

[@jtheracer]

I absolutely love your guys (and gals) video's! Their never boring! And Frank says he's not an actor?? Really?! I am mostly "in front" of the camera kind of guy...but lately doing a lot of behind the camera as well, and you folks have really made it so much better for me thank you!

[@PullMyFocus]

Thanks Scott. Glad you liked it and hope it was helpful for lighting your own videos. Looking forward to working with you too.

[@sameldin2022]

That's amazing .. Liked, Subscribed .. thanks

[@santaclaus9708]

Thanks so much for this! I'm illiterate about the terms and you brought it down to me. Rudolph usually takes care of that subject matter for me. But i needed more for my current needs. Glad you were 'there' for me. I'll be back for more. Appreciatively . . .

[@PullMyFocus]

You're very welcome and I would bet Rudolph's nose puts out some serious lumens.

[@gyrgrls]

@@PullMyFocus His nose wasn't really that bright. It was Santa's sleigh of hand. Rudy had to sign a waiver, called "Santa's Clause", in order to be his pilot. But Dancer and Prancer would give Jen a run for her money, for sure. Jen: You gotta accept the rain, dear.

[@waxbando]

Most creative and informative tutorial 🙏🏾

[@paradoxxaudiovisualproduct9430]

Dude I was geeking out with the intro . Fun .

[@omkarpardeshi5136]

Easy explanation 👍

[@ROVideos]

I haven't finished watching the video but that intro was awesome!!

[@PullMyFocus]

Thanks and you should see Jen (the pinup model) sing, dance, and act. Yes, she's a triple threat actress.

[@gyrgrls]

@@PullMyFocus Glad to see she got a leg up on the ladder of success.

[@EIY_Kumar]

Loved it...

[@DigitalDuelist]

Very good info thanks! Subbed.

[@PullMyFocus]

You're welcome and thank you.

[@marcorossi2182]

amazing! Thanks :-)

[@erictheis223]

Good stuff, very practical, usable explanations. Bravo. BUT - a suggestion: The precise but super technical lead in is likely to send most folks looking for a quick answer fleeing before they get to the good stuff. For me, that greatly sharpened my interest, and made me think "Here's somebody that actually knows what he's talking about!" But I'm an engineer with a strong interest in physics - so probably not your 'typical viewer'.

[@PullMyFocus]

We made that years ago and wouldn't make a lead-in that long today.

[@nenolima5595]

Nice video... pls take out some of my doubts: I have a table with size 2m length and 0.50 width... I would like to put up some spotlight... how distance should they be? How many bulbs do I use and how ( power or lumens or lux or flux) ? Do I need to know just one of this messure or all of them to get a good.

[@voramuj]

Super ✅👍

[@joq702]

Good job. An industry which has not broken down the terminology very well at all for day to day consumers. The #1 thing is what does the actual light distribution look like on or in the actual, intended application? Without testing the luminaire real time, all this fancy math and theory of the light as represented to us remains a "trust me, buy this" sales pitch from a retailer or salesperson to us daily consumers.

[@PullMyFocus]

Spot on. Many industries run into this marketing problem where they use jargon, inside info, and forget we as the consumer don't know what they know. They think they're speaking to us but they're really listening to themselves. But it does mean we get to make videos that demystify it all. Thanks for watching and your good words.

[@raskerwar2508]

Cool T-Shirt you got there. Really cool Godzilla design

[@gyrgrls]

Last time I went to court on a traffic violation, the Judge's name was Candela. He really did shine some light on my case. I plead nolo condere...

[@ACTIVATEDADNANSALIMI1969]

You are a great mathematician.

[@kamramarkand]

We ate testing road lights We can get the values in luminous flux but In specification the value is lux so how can we get the values in lux Can you tell me the conversion factor?

[@guyperson5120]

LOL only seen the first minute so far but that describes EXACTLY how I felt while I was reading the wikipedia page on this.

[@PullMyFocus]

Totally agree and one of the reasons we made this video. Wiki is great but it's usually just the facts with no context to help you swallow all that data. Let us know how you like the rest of the video.

[@jstrndm945]

Great focus gears, but now you blended in to the background

[@sndygskylr]

I still don’t know what headband light to buy for my children while camping. Help

[@chazmalwic1522]

@ Pull My Focus Funny video haha, many people can't figure difference between lux and lumens. Anyway where can I buy that "Light Pod" and how is called? 4:16 - 4:19

[@PullMyFocus]

Glad you liked the video. You can find them on Amazon. We have them listed in our Amazon affiliate store. I put the link in the description of this video for you.

[@ransolinasawyerr4733]

thank you for this video! slightly confused...is canella with two L's different from candela with one? looks like candela with one is metric, not imperial......per Britannica

[@PullMyFocus]

You are correct. It was a mistake.

[@manojgoud8935]

Sir make a vedio on camara movement and angles shots .and about dolly in which shots they are used ..

[@PullMyFocus]

Hi Manoj, we just made a video this week on tracking shots and using a stabilizer to shoot them.

[@aperson1181]

I am trying to survive the dark and rainy periods right now, could you please suggest light sources I could buy and put together to get to 3,000-5,000 Lux to approximate sun and sleep better?

[@PullMyFocus]

Check out the Godox and Aputure continuous LED lights. Certain models put out a lot of light.

[@yesboss9273]

YES!!!! This intro 😂😂😂😂😂😂

[@BadKarma714]

OK using a light meter how do you figure out your what to set my camera in kelvin?

[@PullMyFocus]

You can't. A light meter only measures the total amount of light falling on the meter to give you an exposure. A separate device, called a color meter, is used to give the color temperature. They are expensive. I would set your color temperature based on your predominate light and what you see in your monitor. 5000k for daylight, 3200k for tungsten.

[@theGPC2]

How do you calculate light loss factor? Im confused with the 5700 lumans over 3ft away. How is it only 80fc? What is the formula to account in so i know how to determine what i need?

[@theGPC2]

Please explain the formula?

[@MsTommyknocker]

So the unit for illuminance is Lux?

[@maximilian200057]

1:56 Candelas are metric units as well. www.britannica.com/science/candela

[@KhurramAli]

Hello guys, you made really good video to describe all that about measuring light intensity. The best out of dozen videos I have watched or the articles I have read. While I understood from your video about lumens and lux but but my question is still popping up in somewhere in between. I am actually willing to measure a display's brightness which experts usually measure in Nits or Candela. But I've noticed them using a meter holding up tight on the display (they want to measure). But this way, according to my understanding, gives the reading in Lux. Then how could they convert the reading into Candela when there's no distance involved? I see that those meters are widely available known as Lux meters. I didn't find anything like a Nits meter, or a Candela meter. Yet I don't even have that Lux meter but to test I just found some smartphone app that calculates ambient light in Lux. I am not sure what I did was technically correct or not but I opened that app (Lux meter) on a smartphone (S1) to test the brightness of another smartphone (S2). I brighten up the display of (S2) at its maximum with a full white image and put it down facing towards the ambient light sensor of (S1) - with no distance at all. It indeed gave me the Lux reading of (S2) brightness on the Lux meter on S1. But I don't know what to do with that to convert into Nits? Can you help what should I need to do? I didn't find any platform where i should ask about it, not better than this video. Thank you

[@PullMyFocus]

Hi Khurram, thank you for the kind words and glad you liked the video. On your question. What I do know about measuring the brightness of a display, they measure in nits correct, which is another term for candela per square meter. How they measure it I do not know, sorry. My expertise is measuring light to record for film and video production. Are you looking to measure the brightness of something to record it or to find out how much light it is outputing?

[@KhurramAli]

Oh! that means it simply can not be converted from what I have, to what I need? Thanks a lot for answering.. Yes, I want to record the actual strength of a display brightness. (Not to record the light it's outputting away from it) Usually they do it to tell how a display from a certain smartphone or TV can reach at its brightness. Recording the maximum/minimum brightness on complete whites and on complete blacks can help to tell contrast ratio of the display as well as helps to tell the difference between two displays for sunlight readability That's all what I know or understands. but can't really reach how they do it all. Following the two references from GSMARENA and REVIEWED

[@KhurramAli]

They both are telling pretty same thing about how they test displays of TV or Smartphones respectively but they don't actually tell how they do it. televisions.reviewed.com/how_we_test www.gsmarena.com/gsmarena_lab_tests-review-751p2.php

[@PullMyFocus]

Got it. The type of measurement you're looking for, what you need to do with a spot meter (also called Luminance meter). You look through it, point it at the spot you want to measure and it will give you a reading. We use it in film and video to read the brightness of very specific spots in our frame, like a light bulb, side of an actors face, window, wall etc. In the first link you gave, they use the Konica meter. sensing.konicaminolta.asia/products/ls-100-luminance-meter/

[@deansanchez8987]

What is the ideal number of lumens from a movie projector for home use. Thanks!

[@PullMyFocus]

Sorry Dean but we have no idea. Our focus on lumens has to do with lights on a film set so we can make films. Projecting, that's a completely different world.

[@MattDoesSound]

I'm looking at a product description says "Lumen: 3360Lux/m". Is this the hybrid you speak of that makes no sense? Or am I missing something...?

[@PullMyFocus]

You are correct. That is a confusing description mixing lux and lumen's together that makes no sense at all. My assumption is they actually mean lumens.

[@blissbrain]

I've been trying to find the number of lumens for various tiny lights: beeswax candle, parrafin candle, and the tiny incandescent christmas lights of .4 watts and .7 watts. Anyone here know where this info might exist on line? thanks! (ps: not interested in LED lights, becase those cause me and my beloveds massive headaches due to eye strain. Peace.)

[@letsgobrandon136]

Im feeling like that fella with his hat on backwards lol

[@ajingolk7716]

So lux equal to total light projected to an object so lets say a cob led of 3000 lumen project all that trough a magnifying glass what would be the flux ?

[@YuckFou502]

So like an adjustable tactical flashlight or a maglight, focus setting determines lux but it's always the same lumens.. right? lol

[@PullMyFocus]

Yes and very well put. I'm going to use that going forward.

[@dayztrain5538]

oh man i want your godzilla wave shirt so bad

[@PullMyFocus]

Great shirt right. Do not remember where I got it.

[@zach_harrison]

Great fucking video guys. Thanks

[@PullMyFocus]

Thanks Zach. Now get shooting bro. Your test shots look awesome. Would like to see more.

[@januszciechowskiphotograph7297]

Please can you help me, if I have light that is 8000 Lumens at one meter distance than how much Lux is it going to ba at the same distance ? I'll appreciate your help thank you

[@PullMyFocus]

To do that you need to know how what angle of the lamp is hitting the surface. There are websites were you can input lumens, distance, and the angle and it will output lux.

[@januszciechowskiphotograph7297]

Pull My Focus thank you

[@lbj2277]

So let's see if i got this right. Example: I have a 1000 lumens flashlight and 1000 lumens light bulb. I'm trying to light up my hand 3 ft away. Then the flashlight would light my hand brighter than the bulb, right? Because the bulb "waste" light in other directions that is not my hand, vs a flashlight that focuses all the light on one point.

[@PullMyFocus]

Exactly. If you put that light bulb in a clip light, with its metal dish, you would push a lot of that light in one direction much like the flashlight. Basically, that is what a flashlight is: a bulb in a small parabolic reflector, that you can hold in your hand. Take the flashlight a step further and put a fresnel lens on the front of it instead of a flat piece of glass (a fresnel lens looks like a series of circular ridges and is basically a magnifying glass flattened) and you now focus the beam coming out of the flashlight into a smaller area and get more light in that area. The reflector in the back and the lens in front both work together to get you more light in one direction. This is how the led PAR light bulbs work.

[@lbj2277]

That explains a whole lot, thanks!

[@PullMyFocus]

You are quite welcome.

[@Emiliovstheworld]

what about watts? I'm more used to tungsten lights that use watt mesurments.

[@PullMyFocus]

I hear you, I was too but once you start using fluorescents and LED's they go out the window. In the description for this video there's a link to Wolfcrow's website. He's done some amazing tables comparing watt's to Lux etc.

[@gg-gn3re]

Unfortunately watts are completely useless for light measurement and are only "semi useful" if you're comparing the exact same type of light to another of the exact same type of light. Other than that I can get the same lux output at 10ft from a 1 watt CREE led that I can get from a 300 watt incandescent.

[@deansanchez8987]

Does it make a lot of difference if I jump from 1200 to 1500 lumens for a projector? Thanks

[@PullMyFocus]

No idea Dean. We deal with lumens in relation to lights on a film set. But I would say you've increased your output by 300 lumens, which is 25% increase, but no idea how significant that is.

[@deansanchez8987]

Thanks!

[@imbsysop]

The problem I have with all these explanations is the swift mix up in definitions between Lumen and Lux as if they were mutually interchangeable, same with Candela and Footcandle. Lumen is the intrinsic light yield of a light source weighted versus "human vison" wavelength sensitivity. LUX is the Lumen output "smeared" over a surface of 1 square meter. Same applies to the Candela units of measurement. This also leaves me with the problem how all those light meters are able to measure "LUX" if there is no apparent factor dealing with the surface of the measuring sensor, and using cell phone apps to do this, completely makes no sense to me. So I'd be glad to hear a well argumented explanation :-D

[@PullMyFocus]

Glad it was helpful and yes, we made this video because the topic was so confusing. My understanding is cell phones calculate LUX using the area of their sensor (what it's ratio is to an actual square meter), the same way a standard light meter does. And I would imagine, the smaller the sensor, the bigger the margin of error.

[@imbsysop]

@@PullMyFocus I find that hard to believe. This would imply that th eapp knows all the sensor/camera sizes of all cell phone brands and types? I bought one of those cheap LUX meters and asked the manufacturer how they go about measuring LUX, no answer ! :-D

[@PullMyFocus]

@@imbsysop Each cell phone camera has built in software/hardware that does those calculations. Otherwise, your cell phone camera would be useless to the native software on your phone. It has to detect and calculate the brightness of the image so it can automatically compensate for the level of brightness of your image. If third-party apps had to have a data table in there software with sensor data, that's not far fetched at all. But they get that information from the built-in camera and operating system of the camera.

[@imbsysop]

@@PullMyFocus that's a lot of nonsense you are mistaking a camera exposure meter for a Lumen meter. But never mind, this goes nowhere, typical social media fake news

[@PullMyFocus]

@@imbsysop No that is not what I'm saying. An exposure meter is a lux meter, not a lumen meter. In video and photography, we only care about the lux, the light falling on our subject, to get a proper exposure. The only time we care about lumens is when we purchase or rent lights in order to get a certain exposure, a level of lux or footcandles, on our subject.

[@l3eaver]

@ 1:30 damn them are some blood shot eyes 👀 😂 wha-Cha smoking over there funny guy!?! 🤣

[@PullMyFocus]

It was from squinting at that darn teleprompter.

[@onedirection3510]

Saw a little flashlight advertised as High-power 360 LUX LED. No clue how many lumens this. 🤷‍♂️

[@TotoGuy-Original]

i was hoping to get a easier way to convert lumens to lux, why? i was looking to buy a light meter to measure the light output of bulbs and see if they met the spec's they were sold as and it would also help in future purchases but i cant find any light meter that does lumens its only lux! and as you say theres a complicated formula so there is no real solution for me i dont think

[@PullMyFocus]

You are correct there is no easy way since lumens measures the total amount of light given out in all directions while lux only measures the light falling on a surface at a specific distance. This is why lighting manufacturers for the film and video industry give out lux/ft candle charts for their lights. These charts show what lux/ft candle reading you will get from the light at various distances.

[@pussywran]

So if I'm buying a light bulb that says it's 13800 lm but it's 6 separate lights on one screw in bulb Does that mean each section is 2300 lm Cause it's my understanding that 1 lumen and 1 lumen doesn't make 2 lumens it had to be like 10x that Like to get 2 lumens you would need 10 one lumen

[@erictheis223]

So a 'light meter' actually measures the the light hitting its sensor? Effectively that measurement is converted to lux, taking into account the size of the sensor? That measurement reflects :-) the amount of light reflected from the subject and hitting the light meter - which is what the camera lens will see - which is why it's useful? Thus you should take your lux measurement at the distance from the subject the camera will be? I Am Not An Expert, in case it wasn't obvious. :-)

[@PullMyFocus]

Remember there are two types of light meters: incident and reflective. An incident light meter is placed between the subject and the light source. It reads the light that is "about" to fall on to the subject. It then calculates what f-stop to set your camera lens to (you input into the meter what ISO setting you have set your sensor to). It doesn't take into account how reflective the surface of your subject is, only the light falling onto it. A reflective light meter you use at the camera to measure a spot of light reflected off of a service. A reflective meter you look through like like a mini telescope and point it at a spot on a service to read the reflected light level.

[@erictheis223]

@@PullMyFocus Now I know that. Thanks!!

[@letsgobrandon136]

At 3:30 I'm more confused now than I was when I clicked on this video. You seem to know what you're talking about so I'll thumbs up anyways

[@PullMyFocus]

Don't worry about that point at 3:30. That's just to show how people who are very good with math (architects and industrial lighting designers) can figure out what lights they need based on its lumen output. Just know that lumens is a measure of the total amount of light a bulb outputs, while Lux is a measure of how much light is falling onto a surface (like the face of the actor you're lighting). And thanks for the thumbs up.

[@gyrgrls]

If you hold a burning candle closely behind a thin sheet of paper, you will definitely illuminate it. But if you get the candle TOO close to the paper, you will definitely eliminate it!

[@PullMyFocus]

You win the internet today sir.

[@gyrgrls]

@@PullMyFocus Did I win that, or didn't I? kzbin.info/www/bejne/nZ7JemmsrKakmtk

[@AmourMatthysen]

What is true lumens then?

[@tedtedsen269]

my acebeam x70 light claim 60.000LM how can i measure the correct LM vs claimed LM in my eyes its no where nere 60k, lumen is easy to claim but hard to measure

[@PullMyFocus]

It may be accurate actually as that is one heck of a bright flashlight. There are devices for measuring all the light coming out of a unit, they're used in testing labs. One is a large sphere with a white interior and a meter inside (made by Everfine). You put the bulb or flashlight inside and the light bounces off the white interior and is collected by the meter. But we can't get access to that.

[@PullMyFocus]

Here's the Everfine meter that I would assume the manufacturer used to determine lumens. www.everfine.net/cms/editor/attached/image/20180911/20180911100148_42329.jpg

[@BPUJAA]

how much is 3000 lux in volts or watts

[@PullMyFocus]

Because there are so many different types of light sources, tungsten, LED, CFLs, and different types of lights, par bulbs, standard light bulbs, there is no way convert Watts to lux.

[@rhubarbpie2027]

In Canada, footcandles are called elbow torches.

[@PullMyFocus]

I wonder if that comes from the "elbow" flashlights the military used to use (flash that bends at a right angle at the top)?

[@rhubarbpie2027]

@@PullMyFocus *stares off into distance with look of wonder on face*

[@vikas274]

Explain in Metric system, it will be much easier

[@PullMyFocus]

I explain it in both because most of our viewers are in the US.

[@sl9821]

I don't think candela is imperial. Candela is an SI unit as well. It just has a direction but not distance.

[@directkenxmedia]

SUBSCRIBED!!! LOL

[@PullMyFocus]

Thanks, Direct. And love your color work on your vids. Keep up the good work. (Manu and I are both originally from Brooklyn but we're keeping it real here on the west coast.)

[@tedtedsen269]

i have a flashlight that is on max 32.000Lumen if i have four of them its not the same as 128.000Lumen it doesn't get brighter ust more illuminated

[@PullMyFocus]

Actually yes. Each flashlight stays at 32,000 lumens. If you tape them together, pointing in the same direction, you have a light source equal to 128,000 lumens, that happens to be made up of 4 32,000 lumen flashlights. The only difference is the light source is wider because instead of one flashlight, it's 2x2 grid of four flashlights. And yes, they illuminated a subject more as well.

[@bclaus0]

4:18 Wait, wait, wait, hold up. It's not correct that having 2 bulbs with 1k lumen gives you 2k lumen output, right? But you do get double the lux at a certain distance? I don't think I fully understand yet.

[@PullMyFocus]

It is correct. Remember that Lumens are a measurement of the source of the light, the light output of the light unit. If I have two 1000 lumen bulbs in a lamp as my light source, that’s a total of 2000 Lumens for that lamp, that light source.

[@bclaus0]

@@PullMyFocus So if I get a single 2000 lumen bulb, I will get the same illumination as two 1000 lumen bulbs? That doesn't feel correct, though. I doubt it scales linearly. 10x 1000 lm bulbs don't illuminate as much as a 10 000 lumen bulb, right?

[@PullMyFocus]

It’s the same. Lumens are a measure of the source of light. 2x 1000 lumen bulbs = 2000 lumen bulb.

[@mojbahadori9643]

you guys are funny :)

[@nv7287]

1:49

[@glasshalfempty1984]

RIght off the bat...why the ever living @$%#% is lux more useful when that depends on distance? Lumens is the TOTAL light output and would make comparing brightness SO SO SO much simpler...or at least that's what it looks like on the surface. Lux might be more useful when setting up lights and you need to measure how much light is in any given spot but when buying lights....wouldn't lumens just be so much easier to compare them? ....the video kind of answered that question. Even so, it seems like...to some degree lumens is easier to compare because you don't need a distance. But...if it's not directed....hmmmm....well I learned something and I learned that lighting is more frustrating than I had previously understood it to be :) but this helped me regardless!

[@PullMyFocus]

Welcome to the club my friend. You are correct, it is easier to compare lumens but then what happens to that light output afterward is the other part of the equation (is it spread out 360 degrees or is it in a flashlight direction it all forward?). My understanding is it's a requirement to sell a product in the EU to give its total lumens output. And it's easier to either calculate what it will be or measure total lumens, then give you lux charts. Traditional film and video light manufacturers are usually pretty good about giving tables and charts of foot-candles and lux for various distances for their lights (spot and flood if the light has that feature). But that's because we expect it in our biz. Glad the video was helpful and thanks for commenting.

[@glasshalfempty1984]

@@PullMyFocus it definitely helped! Thanks for the reply and for the video!

[@UHFStation1]

Still don't get it. Need pictures.

[@dudleydooright]

watch this one. kzbin.info/www/bejne/bZyuqnpvlJp9qqc

[@magnusqwerty]

Talking about Amazon using units in wrong way when KZbin uses SI unit wrongly; 80K meaning 80000 subscribers is wrong because 80000 should be 80k, k standing for kilo = 1000 and ALWAYS written with small k.

[@wokthedragon]

Killed cat!!! Don't waste it. Mourn for a minute and put it on your mic... Sorry couldn't help it. I actually like cats. Great content. Learning a lot. Thanks.

[@PullMyFocus]

I like cats as well but you're correct, they're great in windy conditions.

[@lindahaley9384]

Sorry guys..that's (intro) and (off topic).

[@johnwallace2319]

this started so poorly, i was ready to leave, but the moment it actually started, it was extremely clear and simple

[@LuigiHilaire]

😂😂

[@mauricetolentino5591]

Speak in English!! That intro lol

[@scottb.innovations4386]

that was english, Einstein English

[@weeooh1]

Why the sound effects the same time he is talking? Annoying.

[@PullMyFocus]

Because you're not meant to understand what I'm saying when I give the overly detailed, complex explanation of what a lumen is. It's a joke.

[@paulwest4888]

"Contact the manufacturer directly" ROTFLMAO this isn't the 50's

[@PullMyFocus]

Ok, so you can't contact the manufacturer via email or a tweet to ask a question about specs because it's not the 50's?

[@adls04]

Who says rotfl?!?

[@jonbon4047]

Man I fucking hate those videos where one guy plays several different actors. It always come across as so cheesy especially with the stupid screen flips between his characters.

[@PullMyFocus]

Soooo you're saying you like that we didn't do that?

[@cars268]

Cringy

[@PullMyFocus]

Math is like that sometimes.

[@aggyz2198]

ikr lol

[@penbiz6744]

This was no help.

[@PullMyFocus]

Why? What specifically were you looking for?

[@fahimwon4661]

1 Lumens = 1 candle light. The higher lumens per watt the better.. No thanks needed

[@PullMyFocus]

Nope. If only it were that simple. 1 lumen = 1 candela (cd) x 1 steradian (sr), which is a geometric measure of an arc (a cone). There are 4π steradians in a sphere. Lumens is the measure of the total quantity of visible light emitted by a light source. The lumens output of a light bulb given by a manufacturer is just that, the total light output of that spherical bulb (including light lost into the base of the bulb). That means you have to figure in how many steradians are in a sphere. Thankfully other people have done the math for us. 1 cd × 4π sr = 4π cd⋅sr ≈ 12.57 lumens.