Quick little test of photogrammetry software. Nothing revolutionary here… It’s simply something that I’ve been interested in for a long time and haven’t gotten around to working with. Until now, that is, since I have been capturing and modeling real environments for live projections.
From this:
19 still images.
to this:
Click and drag in the window to tumble the geometry.
[kento_3dmv width=”600″ height=”400″ source=”https://relentlessplay.com/wp-content/uploads/2015/01/dextershead/dextershead.obj” ]
The area of a tintype image that gets exposed to the most light essentially becomes a pure silver coating. While the reflective properties of silver make the final image a bit darker than traditional photographic prints, it also gives it a really compelling silvery metallic reflective feel. As a way to highlight those unique qualities, I decided to experiment with hiding LEDs in a box frame to illuminate the image from inside. I also wanted to find a way to intensify the lighting and make the image come alive as viewers got close to it.
Framed!
I inherited some antique oak wood floor pieces and made quick work of it on the old chop saw.
I built some walls behind the front of the frame and attached some LED string lights on it.
I mounted an 8×10 tintype on a black backing board cut to fit at the bottom of the frame’s walls.
Lights OFF / Lights ON
Controls
The next step was to figure out the kind of sensor needed to make the lights come on as a viewer approached the frame. I figured the sensor required would need a range of at least a few meters and be able to return the specific distance to the closest obstructing object. I am not a distance sensor expert so I used the internet to help. In the end, I settled for a Maxsonar EZ0 LV. It’s cheap, it’s got a range of a few meters and it’s got both serial, analog and PWM outputs. I hooked it up to a teensy board and confirmed the sensor was returning appropriate distance values. On the lighting front, I was planning on controlling the brightness of the LED string with the teensy, but since the LED string requires a 12V supply and the teensy outputs only 5V, I used a MOSFET driven by the teensy’s output to modulate the LED’s power supply.
The electronically savvy amongst you will notice that I’m currently using 2 power plugs: a 12V one for the LED and a 5V USB supply for the teensy, which is stupid. I tried to use a voltage regulator to convert the 12V to a 5V supply but somehow it created much noisier reading on the distance sensor… I must have missed a capacitor somewhere. I will try using an Arduino Nano which can take a 12V supply directly.
Code
God, I love the internet!!! I read somewhere that the sensor’s PWM signal was much cleaner so I started with that but I eventually found out that it also is much much slower and wasn’t able to keep up with the rate of change I was looking for. In the end, I used the analog signal and tried to filter it as best I could.
/*
Using the Analog signal from a Maxsonar LV EZ0 to drive a
12V LED strip through a MOSFET.
Take 20 samples, sort and select the median value.
*/
const int anPin = 9;
int anVolt, cm;
const int samples = 20;
int ranges[samples];
int highestReading;
float time;
float previousIntensity;
float maxDist;
float minDist;
int minVal, maxVal;
int mosfetPin = 9; // the pin that the MOSFET is attached to
void setup() {
// declare pin 9 to be an output:
pinMode(led, OUTPUT);
Serial.begin(9600);
time = 0;
maxDist = 450;
minDist = 10;
minVal = 5;
maxVal = 255;
previousIntensity = 0;
}
void loop(){
// print time spent since last loop
Serial.println(millis()-time);
time = millis();
// sample sensor value
for(int i = 0; i < samples ; i++)
{
anVolt = analogRead(anPin)/2;
ranges[i] = anVolt;
delayMicroseconds(50);
}
isort(ranges,samples);
// convert to centimeters
Serial.println(samples/2);
cm = 2.54 * ranges[samples/2];
// shape the curve of the result
float intensity = (cm - minDist)/(maxDist - minDist);
intensity = 1-constrain(intensity,0,1);
intensity = intensity*intensity;
intensity = previousIntensity*.995 + intensity*.005;
previousIntensity = intensity;
// set the brightness of pin 9:
float val= intensity*(maxVal-minVal)+minVal;
analogWrite(mosfetPin, val);
}
//Sorting function
void isort(int *a, int n){
// *a is an array pointer function
for (int i = 1; i < n; ++i)
{
int j = a[i];
int k;
for (k = i - 1; (k >= 0) && (j < a[k]); k--)
{
a[k + 1] = a[k];
}
a[k + 1] = j;
}
}
Next Steps
Once I get my paws on that Arduino Nano board, I can rework my circuit and get the soldering iron out to make my electronics more permanent. I have also ordered a HC-SR04 Distance Sensor to see how it compares to the Maxsonar in terms of accuracy, speed and noise. Also, I need to make the frame a little bit deeper so the light can spread out a bit further across the image.
Which one is cooler?
The ominous cyclopean look or the cute and friendly Wall-E look?
In which we explore the process of exploration, and we take things and make other things from them for the purpose of being joyful in the process of exploration, and mix things up in a way that creates little mental explosions of aliveness, for no other purpose than to celebrate the uncircumscribeable, with a nod to Eraserhead and Quinn Martin. Oh, and also, pictures and tacos come out in the end.
Act I
Ingredients:
-One 8 pound beef tongue
-Chard
-One cake plate
-One 8×10 camera
-One 8×10 black enameled aluminum plate
-One studio with some lights
-Chemistry: collodion, silver nitrate, developer and fixer
-Two onion
-Two heads of garlic
-Three chipotle chilies
-Half a teaspoon oregano
-Eight bay leaves
-Five tangerines
-Salt and pepper to taste
Act II
-Take the beef tongue, the camera and the chemistry into the studio, and lay out the beef tongue onto the cake plate. Decorate the base with some chard leaves and carefully place your lights around the arrangement to highlight the features of the tongue.
-Take some pictures of it and adjust as needed.
-While you’re at it and in the studio, take more pictures of other stuff you happened to bring along.
-After a long day shooting, bring the tongue home, place it in the fridge and forget about it.
-Leave in fridge for four or five days until your wife starts asking what the hell you’re intending to do with that disgusting thing.
-Decide maybe you should make some decisions regarding what the next step is for the tongue.
-Look at a bunch of recipes online, decide to not follow any of them and wing it instead.
Act III
-Put the tongue in a large pot and cover with six quarts of water. Add one of the onion, one of the heads of garlic, and two of the chilies, all chopped. Add the bay leaves, salt and pepper and boil for 4 hours.
-Let the tongue cool and peel off the skin. Cut it in half and slice off a piece a decide it’s kind of weird and probably not quite cooked enough. Pretend you’re cool and that all the strange gristly fatty bits don’t freak you out at all.
-Decide it can be better…
This blog post is starting to be a little text heavy and we know that can be a problem with today’s typical 4 minute attention span reader. Here’s something completely random and unrelated that moves, for the purpose of keeping overactive brains engaged. It’s even interactive, so when you click in it, it does interactive multimedia!
Act IV
-Cut up the tongue in about 10 chunks and saute the pieces in olive oil in a dutch oven. Add salt, oregano, one chopped onion, peeled garlic cloves from the second head, and finely chopped chili.
-Juice tangerine, remove seeds, and add the juice and the peel to the mix.
-Cover the dutch oven and place in oven at 325 for 4 hours, checking it occasionally to make sure it’s not getting too dry.
-Once it’s done, cut it into 1/2 inch slices and sprinkle with chopped white onion and cilantro, and squeeze lime juice on it.
-Serve it to your family and watch them give it the old college try, claim that they really like it but say they’re not really hungry.
-Eat a lot of it yourself because it’s pretty freakin’ good, actually.
-Eat tacos de lengua at lunch for the next 5 days.
-Have your family eventually admit to you they thought it was weird and disgusting, and please never make it again.
-Blog about it later because if you don’t blog about, how can you know for sure it actually happened?
Epilog
In which one has better figure out what the hell to do with the cow’s feet that were purchased with the tongue, because they’s really starting to smell. I hear tendon soup is a thing… Thanks to Tintypebooth for the help with the tintypes.
One of the cool things about a camera is that at its core, it’s very simple. All you need is a lens that focuses light and a surface that this light gets focused on. The process of bending light with lenses to focus on a surface was first explored during the Renaissance with the camera obscura. It wasn’t until the 19th century that people figured out how to keep a record of how much light hit a particular area of that surface. Anyway, to make a camera, all you really need is a lens and a surface for the light to hit, and to create an image from a camera, you either need to trace the image you see projected on the surface or you need some kind of coating on the surface that reacts to light.
Is that a large lens in your pocket?
After giving me a taste of 4×5 tintypes, my buddy at Tintypebooth showed me some large old lenses from photographic systems used in spy planes that he had bought on ebay. These things are serious! They are very heavy and the glass is super thick; there is just something massive about them, and when you hold one and feel its weight, you can’t help but be awed by their image making potential and you get possessed by an urge to unlock that potential. He pitched the idea of building a ultra large format camera with one of them, a little “Kodak Aero-Ektar 24” 610mm” number, weighing in at just over 10 lbs and sporting a few scratches I like to think were caused by the strafing of some of the Luftwaffe’s last Messerschmitts.
Let’s decode those numbers, shall we? The 24” is the size of the image plane and 610mm (also 24”) is the focal length.Based on my previous post about lenses, it means that at its shortest, this camera will be a little over two feet long. At four feet of distance between the lens and the plane, the image on the focal plane will be the same size as the subject in focus four feet from the lens, and six feet will create an image bigger than reality. The film holder will need to accommodate plates that will be 24 inches on one side. I may need a bigger car…
I need a plan
Patience is a virtue I’ve always been in somewhat limited supply of. We have this killer lens… What’s the fastest and cheapest way we can get a picture out of it? Sure, we can design a fancy camera with a lot of bells and whistles but it would take a long time and cost a pretty penny. For now, I just need a bare bones proof of concept prototype. I’ll focus on the basic pieces and see if I can build it myself. I’ll build the back out of oak and do all the struts and supports using aluminum channels. The animated image above is a Maya model I built to scale that shows how all the pieces need to fit together. It doesn’t look too difficult, does it? One thing not shown in the animation is that the back that will hold the plate will be interchangeable with another back that will have the ground glass necessary to focus. The process will be as follows: first you will use the ground glass back to focus, slide it out, and then slide in the film back to load your camera.
Baby got back
Kim Kardashian’s got nothing on this bad boy! I built this 24″x20″ film back over the past couple weeks. I’m not a great builder and my Home Depot tools are a bit wobbly so I wouldn’t call it fine craftsmanship but it will hopefully do the trick. Oh, and did I forget to mention it’s not exactly square? Yeah… Let’s just say it’s square enough. It’s made from 1″x2″ and 1/4″x2″ red oak lumber which I routed to get the insets. It will make a great example when we eventually hire a finish carpenter for the next fancy version of the camera. Here are some pictures of the various pieces it’s made of (you can also see that I like to wear my slippers when I take pictures of my handy work).
More to come…
Here are the steps that come next and will be documented in a hopefully not too distant future.
I already bought the aluminum extrusions that are necessary to build the film back support, the lens plate holder, and the rails. I will need to learn how to properly drill in aluminum and figure out how to connect all the pieces. (anyone in Venice with a drill press?)
I will built the lens plate, mount the lens on the plate, and mount the plate on the rails.
Last will be creating the bellows. Not too sure how that will work but what the hell! We’ve got a few ideas. I’m sure we’ll figure something out.
If you ever want to embark on the foolish pursuit of building a camera, you will need to understand how lenses work. The three attribute that control the behavior of a basic camera lenses are focal length, format and aperture.
Focal length
The focal length is the distance from the lens at which infinite rays converge. For example, if you have a 50mm lens, infinity is in focus when the plane of the image is 50 millimeters away from the lens. A lens’s focal length is a factor of how much it bends the light. The more the bend, the closer to the lens the rays converge and the smaller the projected image. This, in turn, means that the focal length can also be used as an indication of the magnification of the image.
Format
The format represents the intended size of the image plane that the lens is designed to project onto, such as 35mm or 4×5. The combination of the focal length and format determine the lens’s field of view. This is why a lens with the same focal length gives you a different amount of magnification on different formats. (illustration)
Aperture
The aperture gives a measure in f-stops of how “fast” the lens is. It is often thought of as the size of the opening in the lens, but in photography, it actually is the ratio of the focal length over the diameter of the lens opening. This has the advantage of remaining proportionally equal across the different sizes of photographic systems. If you use the same f-stop in a tiny phone camera and a big SLR using the same ISO setting, the same shutter speed will expose both images similarly. As the size of the opening increases, more light gets in but the thinner the focal plane is.
Finding the focal plane
The last relevant piece of information is the formula that determines the distance of the focal plane to the lens for rays that are closer to the camera than infinity. The relationship between the distance of an object to the lens (S1), and the distance of the lens to the focal plane of that object(S2) is defined by this formula: 1/S1 + 1/S2 = 1/focal_length
Solving for S1, this becomes: S1 = (S2 * focal_length)/(focal_length - S2)
If you plug in your own numbers, you will notice that the closer your object is to the lens, the farther away the focal plane will be from the lens.
Useful python functions
# Given a specific focal length and distance to subject, how close to the lens does the image plane converge?
def distanceOfFocusPlaneToLens(distanceToSubject, focalLength):
v= (focalLength*distanceToSubject)/(distanceToSubject-focalLength)
print ("when subject is at %s the focal plane is %s from the lens" % (distanceToSubject, v))
Just like marks in the vinyl grooves of an LP record are the direct physical imprint of a measured pressure wave that one traveled through space, the presence of silver on a tintype plate is the mark left by all the photons that hit it. We shepherd a series of physical processes and transform matter to create a unique, tangible artifact that will stand as an independent physical record of our existence at that particular moment in time. In an era of increasing digital ubiquity, relentless inquisitors want to reflect not only on what has been gained but also on what has been lost.
Matter matters
There is something profoundly human in the drive to make a physical imprint on our environment. We are driven to manipulate the physical world around us and make it hold something of us. We integrate ourselves into the universe by making our experience a part of that matter. The rock is hard, it’s millions of years old, and it was carved by someone at some point. When we carve that rock, we transcend the constraints of the the laws of physics that rule our lives and we have finally become part of the big story. We can die but we still existed…
We ask the universe to be the guardian of our humanity, and by universe, I mean “atoms and particles and time that form what we perceive around us, that we’re not even sure what it is, where it starts or end, that we’re made of but somehow feeling separate from…” sense. We ask it to provide a surface for us and the process of transcribing this incorporeal mental construct into a physical manifestation bridges the gap between our experience and the physical world. Then, when someone else witnesses this mark we made, it creates a continuum which we need in order to function in the great mystery.
Bytes bite
An electronic record doesn’t support us in the way that a physical one does. By definition, it is not continuous. It systematically quantizes anything we feed it, regardless of its significance, and encodes it into endless streams of seemingly random on/off states from which we can perceive neither structure nor meaning. In order to consume a digitized version of something, we rely on a decoding process to reassemble the raw data in a way that creates the likeness of the original. Alternatively, we also rely on computing power and statistical algorithms to generate a signal that is altogehter artificial but that produces something we recognize as familiar. In either case, the stuff that holds the meaning is transient and immaterial; it reminds us of something but it is not that thing itself. As digital tools become more powerful, the illusion of similitude will become increasingly convincing but ultimately, it will never have the life of something physical. It may have a life of its own but it’s in an alien world of pure logic and without senses that we peer into through shiny devices and smooth interfaces; they lure us in with the illusory promise of infinite creative control but ultimately filter out all that is intangible in the world we actually inhabit. The machines aren’t able to transcode what they can’t quantify, the mysterious, the unexplained, the sacred. They digitize and represent the surface with methodical precision but they don’t capture the essence.
Especially if the power goes out…
Herding photons
Going back to the original question: why do I enjoy making tintypes? I love the fact that each exposure results in a single tangible artifact that frees you from the crazy-making tyranny of unlimited undos. You prepare the shot as best you can, you commit your actions to the plate, and you see the results of it. Then you move on… It takes purpose, vision, courage, and conviction, because you can’t “fix it in post”. It’s a truly magic process, too, specially when you dunk the developed image in the fixer and watch the positive result appear through a milky cloud. I call it the Harry Potter moment because it looks like a VFX element from those movies, except real. Also, the way we have been working, it’s a very social activity. It takes about twenty minutes from start to finish and people tend to gather around the booth chatting and observing the process, usually with smiles on their faces. We take our time, we experiment…
You absolutely need to know about tintype photography! Tintype photography, also sometimes referred to as wet plate or collodion process, is an image making technique developed in the early 1850’s and was widely used through the second half of that century because of its ease of use, its sharpness, and the immediacy of the results. Technically, the wet plate process can be used to shoot negatives on glass which can be used later to create prints or to shoot tintypes which yield a single positive on a dark opaque support.
Jason, a friend from my old job, is a complete film and old camera junky and, with the help of the internet, had been putting together a kit that would allow him to experiment with the process. He introduced me to it and I was instantly hooked. Since then, we’ve been geeking out together and I’ve been helping out where I can on Tintypebooth with the goal of creating a mobile tintype kit. We’ve shot 4×5 portraits at the Venice art walk and Tarfest, and Jason sets up for portraits every Saturday at Bar Nine, a groovy coffee lover’s destination in Culver City.
The process
It’s actually surprisingly simple. The whole process takes about 15 minutes and consists of the following seven steps. Don’t be intimidated by the mention of the various chemicals and other fancy sounding science lab-ey processes; I personally wouldn’t know silver bromide from halide crystals if they wore name tags. You can buy all the stuff you need on the internet.
Pouring the collodion on a dark enameled aluminum plate
Coating: a black enameled aluminum plate is coated with collodion, a viscous solution containing salts.
These are the portable darkrooms we built. right = sensitizing, left = developing.
Sensitizing: as soon as the collodion starts to gel, the plate is taken into a portable darkroom, dunked into a silver nitrate solution which turns the salts into light sensitive silver halides, and loaded into a film holder ready to be exposed
Exposing: this is the “taking the picture” part. The ISO of the plate is somewhere around .5 so fast lenses and a bright flash are used to avoid motion artifacts.
Developing: the exposed plate is taken back into the darkroom. An iron solution is poured on it until the the exposed silver halides turn into silver metal, at which point the developing process is stopped by rinsing off the solution with water.
A developed plate is being dunked into the fixer
Fixing: at this point the plate is still fully covered with silver, some developed some not. The fixer dissolves away the undeveloped silver. The silver remains on the areas of the plate that got the most light and the areas that got less light reveal the dark enamel support.
Washing: once the undeveloped silver is fully washed away, the plate is rinsed to get rid of any remaining fixer.
Preserving the plate for (near) eternity by applying varnish.
Varnishing: once the plate is dry, it is still very delicate and the coating can easily be damaged. A coat of varnish is used to preserve the plate.
Although looking at these images on a computer screen really doesn’t do any justice to the feel of handling the actual object itself, I’m including the scans of a couple portraits I did a while back to give a sense of the look.
What’s the appeal of doing tintype?
Stay tuned for part 2 of this fascinating series in which I use very long words to explain why I think tintypes are a very relevant medium to experience in our hyper digital world.
All pictures on this page by Sary Madsen at Tintypebooth
