Posts Tagged ‘photo’

« Older Entries |

Building Ironman: MIT Media Lab Biomechatronics Shoot

Tuesday, June 11th, 2013

A couple of weeks ago I did a shoot at the Massachusetts Institute of Technology’s Media Lab for the Biomechatronics Group (how’s that for a name?!). Now that the client has seen the images I get to write about it!

Given that it’s MIT, I was expecting to be amazed by what the people there were working on. Boy was I right. The “Biomech” Group is a small group of a dozen or so researchers who are, basically, building Ironman. Founded by an engineer and rock climber named Hugh Herr who lost both of his legs below the knee to an ice climbing incident (and who responded to the tragedy by designing and building himself artificial lower legs so good he could continue rock climbing), the Biomech Group has developed artificial biomechanical prosthetic limbs that move and function the same way human limbs do. The Biomech Group is redoing its website, and I was called in to create photographs of some of the things they’re working on, such as a biomechanical ankle and knee. Below is one of the photos from the shoot, of the current generation knee that the lab is working on under the direction of Postdoctoral Associate Elliott Rouse.

Massachusetts Institute of Technology Media Lab Biomechatronics Group Knee by Elliott Rouse

©2013 Chris Conti Photography. All Rights Reserved.

In order to recreate the functions of human limbs in their biomechanical ones, the members of the Biomech Group need to have a deep and precise understanding of the motions and forces at play in the normal function of human limbs. In order to precisely measure the movements the human body makes in a natural stride, the lab uses an infrared motion capture system (similar to the systems used by Hollywood in the creation of lifelike animation and special effects) which consists of an array of infrared emitters and cameras recording the precise position of spherical “markers” that reflect the infrared light which are attached to strategic places on test subjects’ bodies.The below image is of Postdoctoral Associate Jared Markowitz on the motion capture system.

Massachusetts Institute of Technology Media Lab Biomechatronics Group infrared motion capture system with researcher Jared Markowitz

©2013 Chris Conti Photography. All Rights Reserved.

This was without a doubt one of the coolest and most interesting photoshoots I’ve ever done, and I can’t wait to come back and work with the Biomech Group again.

Tags: , , , , , , , , , , , , , , , ,
Posted in Uncategorized | No Comments »

How To Color Balance Mixed Lighting Sources

Tuesday, March 5th, 2013

I just finished a series of four blog posts talking about the various advantages and disadvantages of different types of lighting for photo and video work (the first post, with links to the others, is here), and why I’ve decided, for the time being, to use a mixed kit of fluorescent and LED lights. This kit is great and should serve my needs very well, but there is one hurdle that needs to be overcome first: while these lights are all advertised as “full spectrum” and “daylight balanced” at 5600K, in reality they all have visibly different color temperatures, so they need to be balanced with each other in order to work well being used together to light the same scene. In this post, I’m going to give step-by-step instructions on how I took three different lights with radically different white balances and balanced them to work together beautifully.

Before: Unbalanced

Before: Yuck. When white balancing for the mini LED panel on the left, the fluorescent softbox in the center is very green and the LED 1x1 on the right is slightly magenta.

In the image above, which I designed intentionally to exaggerate the color balance differences of the three lights, I placed (from left) a miniature LED panel, a fluorescent softbox and a 1×1 LED panel next to each other and aimed them at a uniformly white ceiling. The difference is striking (and awful).

Before: Yuck

Alternately, the same image above, only this time white balanced for the fluorescent soft box in the center, the LEDs on the sides are both overly magenta and orange.

As is, it would be very difficult to use these lights in a scene together without them appearing different colors. So they need to be balanced together. How to do this? Gels! Pulling out my collection of gels, I got to work.

I keep an assortment of gels to color balance pretty much anything (from left to right): CTOs, CTBs, Plus Greens and Minus Greens each in 1/8th, 1/4 and 1/2 densities. With this assortment, no matter which way a light is off balance, I can balance it.

Gels Gels Gels!

Gels Gels Gels!

In order to balance the three different lights (from three different manufacturers!) I started with the one that is most difficult to gel: the fluorescent (this is one of the biggest weaknesses of fluorescent lights in my opinion… they’re a pain to gel). I used that as my basis and then adjusted the other lights to match it.

It is possible to simply judge the color of a light visually in comparison to others next to it, like in the photos above, and to experiment with different gel combinations to get the lights to the point where they visually look the same to the eye, but “eyeballing” it like that is extremely difficult to do accurately; I have a very good eye for color (I scored a 19 on the X-Rite Online Color Acuity test! Take the test yourself, it’s fun!), and even I can’t achieve the level of precision that I want by eyeballing it. So to measure the color balance precisely I decided to use a couple of precision instruments: my camera and computer.

To start with, I set up a simple 18% neutral gray card on a light stand (I use this one from Amazon… it’s cheap and does the job well), along with a color chart. I lit the gray card and color chart with the fluorescent light (placing the light at an angle so that the light is illuminating the card but not reflecting glare). I then blacked out the windows in my office and shut off all the other light sources (overhead lights, computer monitors, etc.) so there was no “contamination” and I knew all the light hitting the gray card was from the light in question, and I took a still photo of the gray card and color chart with my Canon 5D Mark II camera in RAW format.

Gray Card and Color Chart

Gray card and color chart on stand for determining exact white balance of a particular light

I downloaded the photo onto my computer, and opened the file in Photoshop (you could also use Lightroom or any other application that can work with RAW files, I just happened to choose Photoshop). Using the White Balance Picker / eyedropper tool in the Adobe Camera Raw conversion screen (the same tool is in the Develop tab in Lightroom in the White Balance box), I sampled the 18% neutral gray card to set the proper white balance for the image, the values of which are then displayed in the white balance section on the right (it is a good idea to click a bunch of times in a few places on the gray card as the individual measurements will vary slightly, then average the values).

Sampling White Balance in Adobe Camera Raw

The White Balance Picker tool is the eyedropper icon near the top left. I sampled a spot on the neutral gray card, which gave me the white balance values shown in the white balance box at the top right.

Sure enough, I now saw numerically what I had seen visually on the wall: that fluorescent light was very, very green (+28 tint!). Since that is the light that was most off balance, ideally I would have gelled it to match the other lights, but since this light is so difficult to gel and the other are so much easier, I instead went the other way around and gelled the others to match this one.

With the temperature and tint white balance values for the fluorescent light in hand, I then repeated the process (blacking out the room, lighting the neutral gray card with a single light source, and shooting a photo) for each of my other lights and then found the white balance values for them as well (I found that my miniature panel has white balance values of 5100K temperature and -3 tint, and my 1×1 LED panel is 5050K temperature and +5 tint).

With that information, I then knew precisely how off balance my lights were from each other. I then added a gel to one of the lights, repeated the process of measuring the white balance values, and noted the numerical effect of a particular gel (bear in mind that as much as the gel manufacturers try to keep the color of their gels as pure as possible, a Plus Green gel will never be purely plus green…for example, my Rosco 1/4 Plus Green gels turned out to add +28 points of green tint, but also knocked off 300 degrees of temperature. But after measuring the color balance values of each light and the color effect of each gel, it was very straightforward to figure out which gels to add to each light to balance them together.

In the end, to balance my LED panels to my fluorescent lights, I needed to add 1/4 CTB and 3/8 Plus Green (one 1/4 and one 1/8) to my mini LED, and 1/8 CTB and 1/4 Plus Green to my 1×1 LED, which, while not numerically perfect, got my lights as closely balanced as possible with 1/8th-increment gels. Now I can comfortably use all of my lights in the same scene together and be confident that their colors will be balanced and visually indistinguishable.

After: I've Brought Balance to the Force

After: I've Brought Balance to the Force. While I can still see differences on this uniform white wall, in practical use these lights will never appear unbalanced.

 

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Equipment, Gear, Techniques | 6 Comments »

Tungsten vs. Fluorescent vs. LED lights: Portability and Ease of Use (Post #3 of 4)

Thursday, February 28th, 2013

This post is third in a series comparing the various types of continuous lights for photo and video work (it’ll definitely make more sense if you read the previous ones).

Post #1: Choosing Lights: Tungsten vs. Fluorescent vs. LED

Post #2: Efficiency (i.e., power usage) and Heat Generation

Portability

This is also something that is less important for photographers and videographers who work primarily in a studio, but for someone like me whose work is almost entirely on location, it is important. Tungsten and HMI light heads are usually relatively compact, but they are fragile; the bulbs are made of very thin glass and even thinner filaments, and can break if jostled around too much (especially if they’re cold, as tends to happen here in the northeast in winter). Also, since tungsten and HMI lights get so hot when they’re in use, at the end of a shoot they need to have a fair amount of time to cool down before being packed away or they’ll melt case fabric or padding or cables, gels or whatever else they happen to come in contact with in the bag or case… and a melted plastic power cable just sucks.

Fluorescent light heads have got to be the worst when it comes to portability. Since they don’t get hot you don’t have the issue above, but instead the bulbs are larger, bulkier, and even more fragile. My 3-head fluorescent kit is HUGE, because the bulbs are so fragile they need to be transported in individual cases (and with five bulbs per head, that means I’m carrying around 15 bulb boxes in the kit).

Definitely better in the studio: moving fluorescent fixtures is a huge pain.

Definitely better in the studio: moving fluorescent fixtures is a huge pain.

I can drive my fluorescent kit to a location, but don’t even think about flying with it… the kit is bigger than airlines’ maximum allowable suitcase size, and even if you could get it on the plane, by the time you picked it up at baggage claim all the bulbs would be shattered anyway.

And then there are LEDs… oh, blessed LEDs. LEDs are tiny, compact, rugged and oh-so-easy to travel with. Since they have no bulbs and no glass, LED panels are by far the most durable and least fragile of the lights here. Advantage, LEDs.

Speed of Setup and Ease of Use

Speed of setup is another issue that studio dwellers probably aren’t terribly concerned with, since lights that live in a studio frequently can stay set up and don’t need to be broken down between shoots. But for those of us always on the go it is a consideration. And here once again, fluorescent heads are the clear loser. Setup of tungsten and HMI heads is pretty straightforward: you put the head on a stand, plug it in, attach whatever modifiers you want to use, and you’re good to go. Takes a couple of minutes per light, tops. With fluorescent heads though, it’s a different story. In addition to all of the same steps you’d take with a tungsten head, with fluorescent lights each individual bulb (of which there can be anywhere from three to six per head, depending on the model) has to be carefully removed from its case and carefully installed into the head before any modifiers are attached, drastically increasing the setup time. LED panels, on the other hand, couldn’t be simpler to set up. You stick the panel on a stand and plug it in. Done. One of these lights can literally be set up in under 30 seconds. Advantage, LEDs.

Usability is a much more complex question (and a really important one). Here, tungsten and HMI lights really benefit from having been around for far longer than LEDs and fluorescents. The design of tungsten and HMI heads have been refined over years, and a whole universe of accessory modifiers have been developed to work with them: Fresnel heads use a lens and a moving focusing mechanism to allow light from these heads to be tightly focused into a spot or allowed to spread more flood effect. All manner of modifiers (umbrellas, snoots, gobos, softboxes of every conceivable shape and size, etc.) have been designed for these lights, and as a result they are extremely versatile. Fluorescent and LED lights, however, unfortunately are still new enough that for the most part these accessory modifiers are not yet available for them. Additionally, the design of most of these lights prevents them from benefiting from Fresnel-type housings, so their beam tends to be very wide (although a couple of companies are just starting to make LED Fresnels… take a look at these Arris). As a result, the light from panel-type LEDs and most fluorescent heads disperses quickly, so these lights tend to have short “throw” distances. Coupled with the lack of modifiers, this limits the versatility of LED and fluorescent lights. I am certain that modifier manufacturers will quickly start designing softboxes and other accessories for them, but for the time being, this leaves fluorescent and LED lights at a disadvantage.

Tomorrow’s post, the last in this little series, will look at quality of light emitted by the various types of light (the CRI), and my conclusions.

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Equipment, Gear | No Comments »

Tungsten vs. Fluorescent vs. LED lights: Efficiency & Heat Generation (Post #2 of 4)

Wednesday, February 27th, 2013

This post is the second in what is going to be a short series comparing different types of continuous lights for photo and video use. In the previous post I talked about how in deciding which type of lights to buy in my next round of equipment purchases, there were a lot of considerations. In this post I’ll talk about two of them specifically: efficiency and heat generation (this post will make more sense if you read the first one). Links to the other posts in the series are at the bottom of this post.

Efficiency (i.e., power usage)

Tungsten lights use a ton of power. A huge advantage of HMI, fluorescent and LED lights is that they use a small fraction of the amount of power that tungsten lights need to create the same amount of light. For example, two of these common 45-watt fluorescent bulbs (for a total of 90 watts) are brighter (5600 lumens) than a standard 300-watt tungsten fixture such as this Arri 300 fresnel (5200 lumens). That’s almost four times the amount of light created per watt of power used! For many people, especially studio shooters, this may not be important. For me though, it is. Nearly all of my work is done on location, and sometimes even outdoors, so wall power outlets are sometimes hard to come by. HMI, fluorescent and LED lights use so little power that it is actually feasible to power them by battery (for example, the 1×1 LED panel I just bought has a V-mount battery plate on the back), which is great if access to wall power is difficult, and is pretty much out of the question for tungsten lights. Advantage, HMI, fluorescent and LED.

Being able to power an LED panel off of this is really handy.

Being able to power an LED panel off of this is really handy.

Perhaps even more importantly though, the lights’ efficiency is what dictates their…

Heat Generation (aka, “Will these lights make my subjects sweat and burn me if I touch them?”)

As anyone who’s ever made the mistake of touching a tungsten or HMI light after it’s been on for a while can say, these lights generate heat. A lot of heat. Instant-blistering-burn heat. Additionally, not only do the heads themselves get hot, they also radiate heat toward the subject. So this is a doubly-important issue: not only are “hot lights” inconvenient to work with because you can’t touch them with bare hands (instead you need to use gloves, pliers or another tool when changing scrims, for example), but they also deliver a lot of heat to your subject, which is bad for a whole slew of reasons for a whole variety of subjects: if you’re shooting a fragile object like food or flowers, the heat can wilt, melt or otherwise harm the object. If your subject is a person, the heat can make the person uncomfortable which can lead to a less-than-ideal interview, or cause them to start sweating.

Try this with a tungsten or HMI bulb and you'll end up in the emergency room!

Try this with a tungsten or HMI bulb and you'll end up in the emergency room!

Tungsten and HMI lights get very hot, but fluorescent and LED lights don’t. Both fluorescent and LED lights will get warm to the touch, but will never get so hot that they’ll burn you if you touch them (or, at least, they shouldn’t… if they do, something’s wrong) and they don’t radiate almost any heat to the subject. I don’t shoot a lot of food or flowers, but I do shoot people, and I want my subjects to be as comfortable as possible, so this is a big deal to me. Once again, advantage, fluorescent & LED.

Tomorrow I’ll talk about the portability and speed of setup and ease of use of each of these lights.

(Update: links to the subsequent posts in this series are here:
Post #3: Portability and Speed of Setup & Ease of Use

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Equipment, Gear | No Comments »

Choosing Lights: Tungsten vs. Fluorescent vs. LED (Post #1 of 4)

Tuesday, February 26th, 2013

(Note: I originally started writing this as a single post, but it turns out there is so much to say on the topic that I’m going to break it into several posts. Links to the others will be at the bottom.)

I recently found myself in the same situation that every photographer and videographer occasionally faces. I’m currently expanding my arsenal of photo and video lights, so I’ve had to tackle the question of which type of lights to buy. Since my work includes both still and video (and since I already have a selection of strobe lights that I’m happy with), I’m focusing now on continuous lights that can be used for either still or motion work.

First, some background. As photographers and videographers know, the most commonly used lights have traditionally been xenon gas flash tubes for still photography and tungsten incandescent bulbs for video and film (HMIs are also somewhat common for motion as well, but less so than tungsten). These traditional kinds of lights work very well and they definitely still have value in the right application (in fact, in certain types of applications they’re still the best type of light there is), but they do have significant weaknesses and disadvantages, and recent technological advances have improved other light sources such as LEDs and compact fluorescent bulbs to the point where they too are now practical for photo and video use.

Choices choices choices!!!

Choices choices choices!!!

So we now have this whole range of light sources available to us that includes the traditional tungsten and HMI (such as those made by Arri, Mole-Richardson and many others), fluorescent (in both tube format like Kino-Flos and CFL format like Westcott Spiderlites) and LED (like Litepanels) as well as some even newer and more exotic technologies that are still coming to market like organic and plasma panels (the Zacuto “PlaZma light” will be very interesting to keep an eye on once it is introduced, hopefully later this year).

Among all of these options, how do we choose the right light? Every type has advantages and disadvantages, and as with most things, which is best comes down to your individual needs and what type of work you do. Personally, the vast majority of my work is done on location instead of in a studio, so the factors that are important to me are 1) efficiency (i.e., power use), 2) heat generation, 3) portability, 4) speed of setup and ease of use, and most importantly, 5) light quality (CRI). (Cost is of course also a factor, but with each type light there are expensive options and cheaper options, so that’s less relevant). So for my current round of equipment purchases, I evaluated each of the light types on each of the criteria above. In the next couple of posts I’ll talk about how the various types of lights compare when it comes to efficiency, heat generation, portability, speed of setup and ease of use, and light quality, finally ending with my conclusions and my purchases.

Tomorrow I’ll talk about the efficiency and heat generation of each types of light heads.

(Update: Links to the subsequent posts in this series are here:
Post #2: Efficiency (i.e., power usage) and Heat Generation
Post #3: Portability and Speed of Setup & Ease of Use

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Equipment, Gear, Projects, Techniques | No Comments »

« Older Entries |