Understanding Flash Duration
Flash duration we were debating whether or not to keep this slide in here so again, this is like an excerpt of the full course right it's a little bit of a difficult concept to get what you need to get it because this is taking what we talked about the differences between constant and ambient light or constant flash to the next level and this is the really important part flashes they look like they're firing instantaneously right and for the example we said let's assume that this is one ten thousandth of a second that's always not the case okay now for our eyes it looks like it's actually firing pretty cloak quickly but let's do this I'm going to dial this up to full power ban close your eyes. Okay, if you are watching this uh it's gonna recycle do you see a trail a light trail? Do you actually see it brighten up and then like red kind of as it falls off I used to think that was my eyes like I used to think my eyes were playing tricks on me when I looked at the flash and I'd see it pop...
but then I seem to see like, light dimming away afterwards okay? So just watch it again real quick washington so you can see the light dim do you see it? That's called the flash duration now if you were to slow this down okay, let's say we're using super high speed cameras, right? And we slow this down, but we're gonna use it in our minds. High speed cameras in your heads. I like it. She's got her eyes closed. Beautiful. Imagine this. Okay, what your flash is actually doing is it's powering up when it hits the peak, the burst happens, right? We actually hear that burst. You can hear it when it goes off. You hear that, little pop that's that one hundred percent point when it bursts. But guess what for it to turn back or basically for to go all way back down zero it actually takes time so it's cycles up fires and then it's trailing off so your eyes are actually playing tricks on you. The light is actually getting brighter and then dimmer but it's doing it incredibly quickly when you run it at lower flash settings, right? Like let's say they were at one sixteenth power. You don't see it because it's happening so quick. Okay, when you get the full power, you do see it. Now what we call this is a t five versus a t one time. And I know this sounds like complicated stuff, but it's not manufacturers, this is the funny thing, they're going to play tricks on you they're going to go are flashes are so fast you can use them for anything r t five time is this I want you to be aware of what that actually means a t five time is the amount of time it takes for fifty percent of the flash power to dissipate, so it fires and trails off to fifty percent. Now guess what if you're shooting at full power and it takes let's, say one to fiftieth of a second for your flash to hit that t five time and your subject is moving are they gonna be frozen, right? It works the same way. Constant light woodwork that fifty percent of the amount of full power flash is still a lot of light that has put a putting off. So the mohr accurate measurement is what we call the t one time t dot won t won t win terminator so the t one time tells us how much time does it take for ninety percent? I'm sorry, I'm like walking around so much. I'm kind of just like that. You guys like, follow me around like these poor camera guys. Okay, so for ninety per cent of the light to get dissipated, that's the amount of time that matters to us so that's, when you look at a flash and see how fast can that flash actually fire? That's what matters is the t one time for ninety percent of light to drop away you wanted to be shorter and that's why I like people pay a lot of money for brown color type axe you know those packs because they have incredibly fast flash durations even when used at very high flash powers. So generally the rule of thumb is this every flashes going to defer hire the power, the slower your t one I mean, the more power you're asking your flash to give you the longer it's gonna take to cycle up in power down okay t one time measures the ability that flash to freeze pocket strobes are generally faster, so these guys are generally faster than studios tropes, but guess what? They don't put out as much power, okay, so sample to one time for a five eighty x at full power is one to fiftieth of a second. So and I made this mistake to I was like, you know, have you seen those ring shots where they dropped him in the water and they fire flashes and it freezes it perfectly. The very first time I did that six years ago, I put my flashes right there, I'm like, I need a lot of power, and so I powered him up to like one second and I was like, why isn't this working I can see the rings moving is they're dropping through and it didn't make any sense until I was like, oh, I learned about flash duration I need to power those flashes down and guess what happens at one half power, the duration becomes one one thousandth of a second or near that at one sixty fourth power so low power means one fourteen thousandth of a second so now your flash can actually freeze things incredibly well when it's run of those lower powers. So another great light for studio strobes that they use a lot to freeze things is like an einstein einstein's have very good flash durations and they're expensive as well, so they're really good. The one thing I usually avoid I say of avoiding is like these generic lights that you find on ebay these really inexpensive lights if something's inexpensive if it seems too good to be true if it's something that you know is it looks that way, it probably is okay, you get a lot of super cheap flights there's one light in these times it from andy gac and he was a cif tiger that put all these numbers up on a site which is fantastic and check it out you want more details, but he put up this generic daylight and it actually shows that the lower the power setting, the slower it's getting so at one thirty second it's down a one, one hundred of a second, I mean that's, not even a flash anymore. That's like a short duration constantly. Okay, does that make sense? So what this chart showed was this is one one thousandth of a second drawn out, right? This is that t one time when the flash of powers dissipated to that point that's the measurement that we're looking for. So when you're doing the dance floor shots and this is this is where I'm going to see if it clicked. What power setting on your flash do you think you need to be around? Not the lute we're at, like, one quarter to one it remember that you don't need it to be that fast, you still need some power, but you guys got the idea like you, you're not going to shooting at full power because it won't be freezing, you'll be doing this, and then it'll look blurry, like why's it looking blurry. So at least that one quarter power were probably shooting let's see, at one quarter power it's already, you know, even a half power of flash like this would be around one one thousand two second that's enough to free somebody dancing, right? As long as you're not at full power, basically, you're okay was that too crazy? Was that it wasn't that bad, right about yeah, safe einstein's you if you're shooting with them, are you trying to drop around corporal parr on all your lights? Like yeah, so if you want to use a nice line to freeze, you do need to do the same thing, so just like you would with this, but a quarter power on einstein is, like six times more ten times more powerful than a quarter power and this guy, right? So you would do the same thing, you drop the power, so you get to an adequate flash duration. So this is kind of this is the one thing that people get hung up on, and I can see every one of you have already got it and that's it that's it for balancing now flash too and be like, that's the only things that matter now, we've got it any other questions was a really great question. Cliff, do you use all the same speed lights, same manufacturer for the same color values of the same quality of light? You know you can we like for my pakis troves, I love the metro's plus system, and by the way, I don't use anything I know people always do this online, they're like pi was paid to say that I'm like no, I don't I don't use anything that or I don't recommend anything that I don't use myself personally, okay, so we're not getting paid saying these things the meters plus is a really great system there four hundred bucks, but their full featured meaning that has a built in radio has everything so those ones that I use who's, justin likes his cannon six hundred ex artie's chris likes I think he used the six hundred sorties to it's really a matter of preference, but sticking toe one flash is generally a good idea to so, like you said, consistent color values every flash it's funny like the higher end flashes, you pay that money for them because they make your life easier, right? If we're put together an ad campaign and einstein it's a fantastic light but let's say there's a fifty degree color variants from shop to shop this is what happens basic with these studio strobes less expensive, strobe is going to do everything that a real stroke everything that I'm or expensive one would do, it'll just make certain things a little more cumbersome. So let's say that it's not as precise in its color temperature for wedding the degree who cares it does not matter fifty degrees hundred agrees it doesn't make a single bit of defense but for advertising, if we're putting together things in a campaign that's where using a nicer light would make your life easier okay, so when we talk about gear and we talk about all the good that we use, we try and tell people like, look, we use pro photo we use bronco we use everything, everything has its own purpose. If I can get away with a speed light, I will you know, I'll totally do that the nicer gear you have, the simply your life becomes, but it doesn't make your image is any better if that makes sense, so you could you could do the same thing. You take shots on multiple different, uh, flashes and just fix them in post that's like the worst sentence in the world fix it in post already what we have next, this is one my favorite slides because this is going to another moment. Any other questions? By the way, before we go into this, why do you ever work with a light meter for measuring? Good question? Um, if you are doing like commercial type stuff shoots, yes, but if it's like I'm tethered and I'm doing like a simple shoot in the studio and I could get away without it now like most ninety nine percent of my stuff is without a light meter and it's just because it's easier it's not to say that it doesn't have its purpose it does it makes your life easier if you want to measure very precise measurements then they're great toe have but and a wedding workflow it doesn't really fit so well question in those wedding settings um is do you try and maintain a particular distance because of your flash settings and the way that light travels through a space or a room to your to who you're photographing yes so when I'm shooting like typically I'll shoot on a lot of primes or like if I'm shooting uh portrait or whatever it is that I'm doing I'm general going to get one focal length for at least a couple like thirty seconds or so right so all dialed my flash power as I move I'll move the flash powers will so I kind of like keep it if I'm going to be six feet between you guys I'll keep it at once when I moved to you know this distance I'm going to go like one fourth or one half you know? So I'm just adjusting based on that so yeah thats inverse square law and that's very applicable we left it towards the end so if we get to the bonus stuff we'll talk about it but again that's one of those bigger that's a bigger beast that I don't wantto get too much of it but yes, you do adjust okay we have thirty minutes I want to get into shooting this is the next most confusing thing that people get when they say flash cannot look natural this is what's wrong in their heads okay there's nothing wrong in their heads they're perfectly good people but this is where they're thinking not quite right it's the flash to ambient balance if your image looks dramatic and you don't want to you want to look natural just remember the world's not falling apart my flash to ami imbalance is probably just a little bit off okay what that means is if we want a more natural look we brighten our ambient light and we reduce our flash power okay so as we reduce flash car and brighten ambient we're creating a more natural look to the images so that gives you these examples right here so again the flash is just kicking the motte we call it a kick right we're just adding a kick we're just kind of brighton the model of a little bit so if you look to these images you'll see that she just brightens up a little bit but we still leave the background blown out it gives a very nice natural look same thing here we're just adding is a soft phil same thing here we're still leaving the background blown outward is adding a soft kick if you want dramatic you go to the other side so you pulled down ambient light and you raise the power of your flash, and I know I should have, like flash cards have gone this way, but that would've made all confusing, so we just threw it all in the same direction. So raise flash power pulled down ambient, you get dramatic images, bring your ambien up, pulled down flash power. You get natural looking images. I got, I'll take it, I'll take it.