Tag Archives: camera
Did some more wiring on the pan and tilt #motioncontrol rig, checked the vga line for shorts and confirmed there was no short. One of the motors only travels in one direction and the other is underpowered, so the problem must be the stepper drivers, maybe they aren’t tuned right or a loose connection there #art #camera #cambot #arduino
Continued from: http://bradisdrab.wordpress.com/2013/04/30/cambot-pt4/
I haven’t been 100% satisfied with the movements I’ve been getting from the Pan/tilt head so far. Its promising, but there is some play in the parts which introduces some counterbalancing and wobble. That and the motors turn a bit more quickly than I’d like, which makes small, controllable, incremental, movements a bit tough.
Time to take it apart and rebuild.
I couldn’t get good results with my hand drill. It was just too sloppy, I needed a better way to do it. I wish I had a milling machine, a full machine shop would be amazing, but I can make due, and make whartever I need.I tried pricing out mini milling machines, but they are just too expensive, instead I looked into small drill presses. I found one for a good price and Kyle and I put it together with a vice and the cross slide and rotary table, I had been using as the camera mover previously. I ended up mounting the whole thing to a metal stool I found so it can be wheeled around the shop. Totally custom and it works great.
Thankfully getting better tolerances from this drill press. The right tool for the job. Cambot is reassembled, now with everything fitting together much tighter, and swapped out the motor in the pan for a slower one.
The basic blocking for Cambot’s pan and tilt is finished and working, so I’ve started planning and working out the mechanics for the next two axes. The first of which is pictured above, the rack-focus. This is likely the easiest of the axes; simply a pinion gear mounted to a mini robotzone gearmotor, which will fit with the len’s focus wheel’s teeth. I mounted this motor to a little arm attached to the 15mm rails on the P/T head, so it will remain adjustable for different lenses as well as remianing in position with the camera.
Next comes the Jib, it needs to be able to crane up and down. The Jib is well counterbalanced so won’t need a lot of torque, but with nothing there at the moment it tends to drift slowly.
I spent awhile thinking about ways to hold that axis, and looked at a lot of options, eventually deciding on a timing belt. Also I learned that parts can be ordered in bulk to save money from ebay, so I picked up a bunch of timing pulleys, and bearings. Unfortunately they weren’t as easilly matched as the parts I got from Servocity, so I had to do a bit of work on them to get them assembled.
I fit two idler pulleys and one to drive the belt. Looking pretty slick now, just needs a motor.
With 4-axis nearly in play, and two more on the way, I’m going to have to start thinking about how I’m going to control this thing. My current testing methods the MX2 and can manage 2-axes at a time
This new MX3 from dynamic perception looks interesting, it can control 3 axes, and includes a MoCobus port which could be very promising in the near future, afterall I’ve been loving the Mx2.
My other option is to customize something from scratch using an arduino. I’ve been pouring over tutorials and it actually sounds totally do-able. I’ve been calling that “The Magic Box”, basically a controller that does anything I want/imagine, from stop motion, to live control and follow modes, with programmable control of dynamic lighting, and the ability to import/export 3D camera moves from the computer. One can dream.
Continued from the experiments here; http://bradisdrab.wordpress.com/2012/09/01/air-mortar-pt3/
Not quite ready for “real” pyro, but feeling pretty good about the compressed air rig and battery operated valve, I decided to apply it towards an effect I wanted for Drab Future.
Here is what I was looking at as reference. Specifically I wanted to use it for a blood squib effect and having someone lose an arm. I knew it could explode so it was a matter of seeing how much of a blast it produces, if it is safe for an actor to wear and exactly how it looks/works. I’d never strap it to someone else before testing it on myself first, so here goes;
Continued from here
I’ve made progress on Cambot. I drilled up some stock aluminum bars to fit between the gearing and the rail mounts so now it is all secured together. I also swapped out one of the axels for a carriage bolt so I’d have a way to tighten it down.
So far I’ve worked out the pat/tilt mechanisms and it seems to be working pretty well. I’m driving the two DC gear motors via a Dynamic perceptions AT2 controller.
I’m still a bit concerned about the overall weight and size. I wanted to avoid unnecessary strain on the motors, so I took the camera off the mount while testing it.
Sadly immediately after this test there was a ‘pop’ noise and since then the 12v DC adapter I’ve been running this from stopped working. This was a new power supply, purchased with my AT2 and used only 4-5 times no longer than an hour each time, and and it was hooked up to a surge protector, so I’m at a loss to explain what happened to it, manufacturing error perhaps?. I have no way of testing to be sure it didn’t fry the controller or motors, I can only assume(hope) that is as far as the problem extends. I’ve got a replacement on the way …
I keep reminding myself that I started this project to learn what goes into building something like this more than I did because I couldn’t afford a packaged system.
Continued from; Cambot pt2 (BRAIN storming)
I’ve been thinking a lot and working on my Cambot. I try to keep the end goal in sight as I am teaching myself just enough to make this work. In the end I’m hoping to be able to set it up for both live action and StopMo, on a stage and out on location. So it needs to be somewhat modular and self-contained in the end, so not (solely)controlled by a computer.
I’m not much of an engineer, more of a hardware-hacker and I’m basically teaching myself this as I go along, which is partly why I’m working it out in parts. I’ve also not got access to a proper machine shop, so I’ll either be at the mercy of my friends, looking into buying a mini mill, or attempting it with hand tools.
But first some inspiration from Vimeo user Displacment1, who has some really amazingDragon Stop-mo MoCo rigs;
I’m really liking these designs, modular and adjustable. As much as I like the simplicity of my Geared tripod head I think I’m going forward with this sort of a nodal pan/tilt head design.
Mohan has made some really slick 15mm-based pan/tilt/slide rigs. He appears to be using carbon fiber 15mm rail rigs, so it’s both light-weight and strong! which he has custom built using stepper motors and custom gearing;
Another similar 15mm pan/tilt head was found on the dynamic perception’s forum here. He says he was able to assemble the whole thing for $450, which seems low to me, especially after seeing other offerings.
The miniengine seems to be a really cool way to run time lapse, or shoot-move-shoot based moco. It seems to be well-supported and designed, and actively developed. The next version seems even better, definitely something to keep an eye on…
BFG motion control seems like a great system. They provide a hardware encoding box and GUI interface for designing complex shots. However their price of $1000, which is reasonable for something of this kind, is outside my budget for this project. I’m really hoping to put the whole thing together for 1k, and there is a lot of hardware to put together…
I’m getting close, my research and brainstorming seem to have brought me to a clear path. Well I say one path, but its more like a three phase plan.
- -Realtime mode
- -Playback mode
- -Program mode
Realtime mode – Hardware rig
The first step is assembling the rig, the real hardware of it. That will show me the physical limitations of the rig; size, weight, as well as the number and positions of axis.
This is where I am now, essentially a manual stopmotion rig;
Bogen geared pan/tilt head, mounted to Jib(rigged to raise and lower with an automotive jack), on machinist’s rotary table and linear slide. Current arrangement is set up for manual moments. Turning the wheels incrementally of the geared head and cross slide allow for an animate-able camera.
Pros/Cons; It works… mostly. It is limited to either stop motion animation for camera moves, which takes a lot of patience and focus for long, smooth camera moves. To move increments as well as animating the puppet or prop actually in the scene, or for an actor I can release the jack and move the jib smoothly, for hand-operated movements but its a bit wobbly, and requires an operator.
On to the next phase!
The next phase involves motorizing it all. I’ve got the motions plotted out, but it needs to drive itself, So I’m beginning to add gears and motors now. The goal is to rig it so that it can be remotely operated. (with speed controllers). I’m looking into offset gear motors, DC motors, and gearboxes. I’m planning to work out/test 2 axis at a time in realtime, and possibly set it to record/playback once that is working.
I’m starting off by setting up my hardware to run off an Dynamic Perceptions AT-2 controller, starting with ez-swap dc motor or a a gear motor like these or a DC motor like these.Which will get me the chance to set up all the mechanical parts of the rig properly.
This real-time controlled live action remote rig gives me the ability to control and test two axis of DC motors.
Here is my rig as it currently stands, 2 geared axis hooked up to a joystick
From here, an idea for self-contained playback in the mean time, this servo recorder, seems like it could record up to 3min of motion for 4-axes, and with speed controllers it could control DC motors, then play back recorded motions.
This really seems like a good place to get, since it seems like I’d be able to control pan/tilt/focus and movement, either; slide/track/jib/rotate, however it’ll be $3-400, for it and I’m still not 100% sure it’ll work reliably/repeatably… DC motors aren’t really known for their detail in movements, and while my gearing may help I just don’t know, really people tend to use other types of motor for this sort of design, i.e. steppers or servos.
Program mode MoCoBus Rig; stepper motors, nanoMoCo, upgrade device…
Once the mechanical parts are working for live playback, I’ll be looking into swapping the DC motors for steppers driven by a computer, or potentially some portable brain. Ideally I’d have a magic box which allowed me to move the rig however I wanted, then have it repeat the move and export a 3d camera move which could be imported into effects software.
This post from Dynamic Perceptions got me very excited. There are plans to take the AT2 and use it to communicate with record-able repeatable systems. Naturally it wouldn’t work with DC motors.
If I rig my mover with stepper motors, like these Phidgets or NEMA-17,
or another stepper, I’d expect I need some sort of driver card for each them. I’d need something like the easydriver. I don’t really know a lot about steppers, yet. But I’ll learn.
Currently I’ve got my sights set on Dynamic Perception’s MoCoBus, driving the stepper motors via their nanoMoCo cards. The whole system chain (MoCoBus) will feed into a computer, (potentially a netbook) for movement recording/edit/playback, StopMo, etc. (Software Workflow)The upgrade device will also allow me to drive the steppers and record the AT2 joystick’s movements into the MoCoBus chain.
Then when the upgrade becomes available I can upgrade my whole system to use MoCoBus. Then I would need to swap the DC or gear motors out for steppers to use the nanomoco on,
Itd be great if I could rig all my motors with nanomocos as drivers, control 2-axes of them analog for now. Once its all working smoothly, I’d plan to delve into chaining all the axes via mocobus and get more complicated multi axis moves through Graffik on the computer. And hopefully by that point I’d have access to the adapter and this updated workflow.
Continued here; Cambot pt4
I watched ‘Beyond the Black Rainbow’ last weekend and put together this test video,
This weekend’s tests were all about getting brainstorming on ways to improve Cambot and doing a bit of shooting in the studio. The studio time definitely helped to see what is working on Cambot and where it can use some improvements. The goal of my shoot was to experiment with lights.
I’ve spent some time before working with traditional Image based lighting, where I basically used a reference image from a location to digitally light a 3D model.
The reference image is typically a panoramic image unwrapped from a photo of a chrome sphere. The chrome sphere reflects a full 180 degree image of the reflection and in doing so the reflected light which would be cast upon the object. Typically a gray sphere is photographed at the same time for comparison with the in-progress/finished model.
I want to begin the same way, background locations photographed with reference spheres, then I want to photograph practical scale models to place in them. Typically this is achieved by attempting to mimick the lighting conditions, i.e. “the sun was here so we place a key light here, with a fill light on this side and…”. Then through a process of ‘match-lighting’ a cinematographer/Director of photography can reproduce the location’s lighting.
Now I want to turn this all around. In theory by using these reference images it should be possible to recreate the environment lighting on demand when photographing a practical model or actor. All that would need to happen is for a directional light source to project onto the surface of the model with the same hue and intensity as the reference.
My approach is through the use of DMX stage lighting. There are multi colored lights capable of mixing Red Blue and Green in real time. These are also programmable via DMX512 protocol, so they can be set up to run through pre-set lighting configurations.
I’ve been using these slimpar 64 RGB LED lights from Chauvet. I’ve currently arranged five of these in a half ring around my stage all pointing inward.
I plan to eventually upgrade this to a more automatic solution. There are a lot of software packages designed for stage techs, in fact many concerts and night clubs use these systems. There is also computer soft/hardware solutions more designed for filmmakers and animators like this card for Kuper which fits in with a Kuper motion control system. Or the DDMX-S2 from Dragonframe, which allows stop-motion playback control for incremental programs. For now I’m controlling these via the Chauvet Obey-10 mixing board, which allows me to set sliders for each of the color channels of the lights independently.
What I’d really like is for it to be able to process a ref image or video and reproduce it automatically, or use a video clip and essentially ‘play it back’. It makes sense that through software I could take a reference image and sample the quadrant’s hue and value, and route that into a DMX controller, then those values could be used for control of the lights.
The theory sounds great, but first I have to figure out the physical lighting limitations of this rig and about LEDs in general. I’ve often been warned about color temperature in photography. The difference between Tungsten (3200K), Daylight (5700K), and Fluorescent (4000k). However in attempting to get a clear answer to the temperature of LEDs I went down a rabbit hole. It seems this all goes out the window the moment you start color mixing. It is completely variable, which means it could be anywhere. Added to this LEDs typically have a more limited spectrum, take a look at
LEDs are often assigned a CRI which as I understand it, is how well they can reproduce the sun’s light, and thus how balanced a color will appear when illuminated by it. The other thing I’ve discovered about LEDs is the pulse width of the lights themselves. They aren’t actually constantly on, the light blinks on and off at arate so fast we can’t detect it. For many lights this is slowed down for the dimming feature/effect. This pulse width modulation which our naked eye cannot detect, even at lower frequencies will be detected by the camera when set to a high shutter speed.
I found it really interesting in this test to see the way the light’s wavelengths interacted with the shutter speed of the camera. It seems there are ways to work around it, selecting a lower shutter speed for example, but I haven’t quite figured out the science for it. Looking over forums shooting around PWM seems to be an increasing problem, especially for venue/location photographers;
Shutterspeed and flickering hmis
PWM is not your friend
LED flicker on camera