Understanding Ghosts (and how to bust them): Exploring Photography with Mark Wallace


Hi everybody! Welcome to another episode of Exploring Photography right here on AdoramaTV brought to you by Adorama it’s the best camera store in the world, check them out at Adorama.com Well, I have two models today that are fantastic Monique and Marelie come on out and these guys are going to be helping me explain some things now, this video is sort of an extension of a video that Marilee and I did previously ‘Crazy Fun Light’ and so we had you like moving all around we had a strobe and we also had a constant light and that actually caused a lot of questions. I need to resolve those things and so in this video I really want to talk to you about what happens when you slow down a shutter and how that affects the ambient light and motion, and how when you add a flash to the mix you can include or exclude things, it really makes things interesting I’m going to try to break that down because I think I caused more questions than answers in the last video, so let’s first start with a slow shutter speed and really how our camera, the exposure works in our cameras. So to help you understand this I have a normal glass here and some water if you think of this water as light, and you think of this as exposure, what you’re trying to do is get just enough light so it fills up your glass all the way to the top in other words you want to have your sensor in your camera get just the right amount of light, so you’re not over exposed, in other words water going over the glass or underexposed not enough water in the glass. And so there’s two things that determine if you have the right amount of water or the right amount of light your camera one is how large the opening is in the glass or the carafe that’s the aperture in your camera how wide is that how much is coming through and how much can come through at a different duration. Duration is the time it takes – so that’s your shutter speed! So for example, if our aperture is really small or there’s not very much light we’re just going to get a trickle of light coming into our camera, and it’s going to take a long time for us to get a proper exposure, and if we don’t let our camera go long enough, I’m going to be underexposed But, if we have a lot of light or our aperture is open really wide, well you can see that we can use a shorter shutter speed, and so those two different things really play into… whoops Play into.. how our camera’s exposure works. Now with a really long slow shutter speed 2, 3, 4 seconds… something like that. Our light is just sort of trickling into the cameras trickling into the sensor and so that has an impact on motion and to explain this what we’re going to have is Monique and Marelie are going to hop back here on this seamless white, and what I’m going to have them doing is.. 1. so Monique is going to be standing still 2. Marelie is going to be moving and we’re going to see the difference with a long exposure, how motion will change how that light shows up on the sensor, and how being really still changes how that light shows up on the sensor then add a flash to the mix, and then I’m going to start doing some interesting things and so without further ado we’re going to start shooting that right now, alright well let’s put this into practice by understanding the principles of a slow shutter speed and what that does to our light as it’s coming into our cameras sensor, some really interesting things happen and so what we’re going to do is we have Monique and Marelie back there. They’re going to be walking back and forth and doing some things but let me show you the setup, I have my camera here and I have this set to a four second exposure so I’m shooting f16 ISO 200, I have a neutral density filter on the front, so we can really get that long exposure so, the important thing to understand is this is a 4 second exposure now back here we also have a studio strobe, we’re going to get to that in a bit so just don’t worry about that right now, we’ll get to it in a little bit so the first thing we’re going to do is Monique is going to exit and then Marelie is going to get ready to walk across our seamless background. I’ve already focused this and so all we have to do is tell Marelie to go are you ready okay watch what happens one two three go ahead and so my shutter is open it’s going to be going for four seconds so 1,2,3,4 – it just ended now if we look at this image what you see here is we have just a white background with the trace of Marelie’s feet so you can see your feet just a little bit of a ghost so what the heck happening so remember that glass of water is pouring that water and how light trickles into get a proper exposure well our cameras sensor, isn’t just a glass where it’s containing the light in one location, it’s a sensor that captures light across that sensor, so it’s actually millions of little glasses called photosites that’s capturing the light that’s coming into our camera so what’s happening is… Marelie, come on over here, so we have this 4 second exposure and so if Marelie just stood right here and didn’t move we would have light coming and bouncing off her shoulder into the camera and after it’s bouncing and going into the camera for 4 seconds then she would be properly exposed right here, but she’s moving, and so what’s happening is, the light’s coming in,, it’s sort of hitting her, so take a step forward, but now she’s gone, and so on this sensor, what we’re seeing is the light bouncing off the seamless white, and coming into the camera, and she’s right here, she’s moving forward go ahead and take a step, so now she’s not here anymore she’s not there long enough we’re seeing light hit off this back and come into the sensor and as you take another step forward that just happens over and over again and so she’s just not anywhere long enough for the light to hit her and then get into the camera for a long enough period of time to get a proper exposure she just doesn’t show up at all because the light isn’t on her long enough except for her feet. So come on back. Notice that when she’s walking she’s taking a step and then ok take a step that way Yep, so like this notice her foot is standing still her body’s moving, foot standing still body moving etc. So that’s why we’re getting the little ghosts of her feet, because her feet are staying in one place longer than the rest of her body is, so we’re going to prove this out, so Marelie go back to your starting point. Monique is now going to come onto the scene, and Monique is going to stay completely still, as much as possible, she can’t stand completely still for 4 seconds, you’re going to do the best you possibly can Alright! So here we go, she’s going to stay completely still, and then on the count of three we’re going to have you walk through this, ready 1,2,3. So Marelie is walking Monique is completely still, now watch what happens when we look at this image here we can see that we have a blurry Monique because she couldn’t stand completely still, but all that light was coming in bouncing off of her going into the camera, going to the camera for 4 seconds, we have a solid Monique but Marelie is moving, so the light wasn’t able to bounce off her long enough for her to even show up, and so that’s what motion does to an image, so if you have something that’s moving… along a path well, they just don’t appear at all ok. Now that we understand that, let’s add a flash to the mix, now the only thing that I’ve changed here is I’ve taken my camera and now we’re at a 1 second exposure shooting at f16 ISO 200, I took that neutral density filter off because now we’re using this studio strobe and I wanted to make sure that it had enough chance to get into the camera, and have a proper exposure, so I just wanted to remove that neutral density filter to do that, and we don’t really need a 4 second exposure, so 1 second exposure and Marilee is going to be walking across which is about half way across. I’m going to push this button on the remote, that’s gonna make the flash fire, and some interesting things are going to happen, so are you guys ready to do this? So watch what happens. I’m going to count to three, Marelie is going to start walking, about halfway through going to flash, and then we’re going to see what happens ok? Marelie, go ahead and start walking, she goes… boom! Ok, that was our 1 second exposure now what we see here is we still see Monique she’s frozen, she’s exposed just like we normally would see her but we have a ghost of Marelie, so how is that happening? So Marelie, come back out here what is happening here, is all the stuff that happened before, so the ambient light is still going into the camera. So as she’s moving there’s not enough time for her to be exposed to show up to the camera, but when she gets about right here I fire the flash! Bam, that’s a lot of light coming from that flash! So that is freezing her and that light is going into the camera and it’s showing that ghost of her but she keeps moving and even though that light came into the camera we still have a bunch of light that’s coming off this back wall that’s also going into the camera, and so that shows up and it makes her look transparent, and so that’s why you might see a ghost of somebody, you’re using a flash in a dark room with a really slow shutter speed, so even though the flash is illuminating merrily… we have this white wall here reflecting all this other light that shows up, and makes her look like a ghost! So how do we make her look not like a ghost? Well we need to eliminate the ambient light we can do that really really easily so you’re going to walk again All we have to do is speed up our camera shutter speed on our cameras. What I’m going do is, I’m going put this at my camera sync speed which is about 1/60 of a second where have you come on this side and she’s going to walk again. So now i’m just going to set this up again, I’m going to push this little button here when she comes across, so I am going to put this on the camera so it works Are you ready? Ok, start walking 1, 2, 3 go Click… now look no ghosts at all all I did was they sped up my shutter speed to eliminate the ambient light and all the light we see is from the flash you don’t believe me watch this I’ll take this and turn it off so no flash at all I want to take a picture you can wait Monique, all right click taking a picture and when we look at this what we get a totally black image and so what we understand there is that when you speed up the shutter we can eliminate the ambient light and we only see the light from the flash we start slowing down that shutter, we’re allowing more ambient light, but if you go too far not only are we allowing ambient light, we’re showing motion at the same time we can separate ambient light and motion from our studio strobe, and freezing motion, and then we can start working with this to bring a little bit of ambient light or eliminate the ambient light to create some interesting effects. And that’s what we’re going to do next. Alright, now that we understand the principles of a slow shutter speed, not only showing emotion, but more importantly letting in more ambient light. Speeding up that shutter speed eliminates the ambient light, but we can also have a separate exposure – that’s the flash, and so we can control those two exposures independently of each other, and now we know the effects of each one we’re going to illustrate this with this scene right here! This is the back room of the studio we’re in, and I think it’s really really cool, so Marelie is here and she is sitting, where she is facing this light this is a two-foot octave box with a grid on We’re just getting this pool of light right on Marelie but nowhere else so none on the background, none on the foreground, just this really small pool of light but I love this chalkboard back here, It’s got the Jeremy Cowarts Help Portrait right here, and what that means, and all the information, they’re doing that here in the studio this week I guess, And then there is awesome, really cool doodles back here, so I want to be able to show this, or hide it, and we can do that by mixing that ambient light with our studio strobe, so let’s do that. right now the first thing I’m going to do is I’m shooting at a 1/180th of a second ISO 200 f8 and that’s gonna eliminate the ambient light, and only show what we see from the flash so check this out. So we’re going to have you look perfect just like that. Bam Ok now, look at this we just have this really small pool of light and we don’t see the background because our shutter speed is too fast to show any of that ambient light I’m going to really slow down the shutter somewhere slow this down to about 1/15th of a second, I’m going to shoot again, same exact setup so again ISO is at 200, aperture of f8, but now we’ve slowed that shutter down more ambient light is going to be coming in and so here we go we’re going to look just like we did before, Click! Now check that out, that background just magically appears, it’s really nice now at 1/15th of a second Marelie is going to have to be a little bit still, but she can move a little bit because our flash is freezing her motion, we don’t have to worry too much about motion blur, but if we wanted motion blur, again we can slow that shutter speed down, and then we could have her move, we could do all kinds of things, so now that you know all of those principles, slow shutter speed, motion faster shutter speed, no motion, but no ambient light either. Well thanks so much for joining me for this episode of Exploring Photography Thank You Monique. Thank You Marelie, for being exceptional models and walking around doing all kind of funny stuff Don’t forget to subscribe to AdoramaTV it’s absolutely free so click the button and subscribe today and also check out the Adorama Learning Center where there are types of articles, all about things like motion, and motion blur, and using studio lighting, all kinds of things, anything you can think of it it’s at The Adorama Learning Centre Thanks again for joining me and I will see you again next time.

52 Replies to “Understanding Ghosts (and how to bust them): Exploring Photography with Mark Wallace”

  1. Thanks Mark. You always do a great job of explaining basic and not so basic photography principles.

    Keep up the good work.

  2. This video needs to be the first video anyone getting into flash photography should watch. Absolutely brilliant explanation.

  3. Can some explain the light refraction from the sun Please. You see I can get blue rings in the sky etc…And I use to take sun pics when I was 17 and would see what was normal back then which was small round lights all in a row.But not now.Can you help me understand what is going on. Its a tablet 4 .I can get the same pics with my cheap 4 year old $30 phone from walmart.The new LG androids only pick up some of this light reflection but it's still there.Oh and
    one more thing What is that light bouncing off of to show this light in my camera lens.I think I know but want to get your opinion on this so. I can start digging for more info.

  4. Hi Mark. Was curious about whether TTL was really needed when considering the new battery operated mono-lights (XPlor 600, RoveLight, etc.) Some photographers have said it was not needed (avoiding the extra cost) given the lights typically end up in one spot on the set?

  5. Great way to explain exposure with water. I never saw it before. But there is one slight problem with it. You can have light with different intensity, that would be the viscosity of your liquid.

  6. I don't know why Mark, but this one reminded me a lot of the original Adorama tv days way back. Excellent video! Great lesson taught here. I've learner a TON from you over the years.. Thank you..

  7. Ambient light needs to be qualified — they specify ambient light, but what they actually mean is "lesser intensity" light or light having fewer photons and therefore lesser statistical likelihood of triggering the sensor. This is important to understand because – while perhaps not as common – if the ambient light were "brighter" than the flash, then actually you'd be filtering out the flash, not the ambient light.

  8. Mark, that was so well explained all in pretty much one take! You were born to educate and are a pleasure to learn from.

  9. Hi Mark , Thank you for the video ,its clear and simple , my question is that the flash managed to help you freeze Monika when you selected 1Sec AV but how slow you can go while the flash would still help you freeze Monika ? will she still look sharp if you slowed to 4 sec ? is there an equation ? thank you for anticipation

  10. Does it make a difference when ysing 1st or 2nd curtain sync? I love your tutorials. You are a great teacher/instructor. Thank you for the explanation of aperture and shutter speed. I always explained using a window and blinds or curtains; how big is window & how fast can you open and close the curtains… thank you for an alternate example.

  11. If you have a white background and you dont like shadows in the background how do you get rid of the shawdows? Even though shadows are good for certain images… ~Ben~

  12. Its 2018 and I'm still amazed by how perfectly he poured the glass all the way full without it overflowing, sensational.

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