Whilst my camera and lenses are all good to go, I would probably need to get a fluid or semi-fluid head for my tripod. But that can wait for the time being.

DSLR audio is still lacking for a number of reasons. The microphone is built into the camera body and is just too close to the whirring noises that lenses make. Whether it is focussing or image stabilisation, it can be picked up by the built-in mike. It also doesn’t have a wind cover to shield the mike from the pops and explosions associated with wind blowing into the mike. Recording is monophonic at the very least, and I would hazard a guess that the sounds to the left of the lens are more distinct than sounds from the right hand side which are obscured by the lens.

I intend using a really nice Sony electret condenser stereo microphone and recording the audio into a Sony ICD digital audio recorder in high-rate CD quality audio, but my problem is that I don’t have a solution to mounting the mike onto the camera, just yet.

Browsing the web, I came across a setup which I like. Many microphone manufacturers have a shotgun mike mounted in a shock-cage or housing. In essence suspending the mike away from the framework in a series of rubber bands. Just like this Rode Videomic

Scouring eBay, I came across many solutions like this DSLR shock mount from RoXoniX

But just one minor problem, these mounts come in at about R400.00 excluding shipping, which may be as high as R200.00. All told, this is not in my budget right now. So, in breezes Necessity, the Mother of invention.

I have a plastic and metal hotshoe mount which will work perfectly for a mike mount on my DSLR. I just need to fabricate something to hold the mike. I already have shock cord (rubber bungee cord in braided nylon), a tube to extend and hold the mike in front of the camera and a few odds-and-sods to pull it all together.

Off I went to my local Builder’s Express in my quest to find just the part I need. and here it is: A 50mm T-junction for a washbasin drain pipe, Sexy, eh? The dotted lines are were I intend doing the nip/tuck stuff.

After some cutting, sanding, drilling holes, building up a spot for the hotshoe mount with epoxy and a touch of spray paint, I have the following nifty little mount.

Best of all, the T-junction cost R14.00 and a Sunday afternoon.

Completed, the setup is as follows.

Audio tests directly into the camera mike input are great, the mike is lifted high enough from the lens and audio separation between the left and right channels is superb for ambient pickup as well as primary audio pickup. The shock mount does exactly what it is meant to – eradicate any vibrations from getting to the mike.

Using a longer cable, I can plug directly into the Sony ICD are record CD-quality stereo MP3 files at 192 Kbps utilising all the sensitivity and noise-clipping functionality of the ICD. Best of all, I can monitor the audio into the ICD using headphones/earphones and with the ICD switched to “hold” mode, I can slip the audio recorder into my pocket and not worry about it.

Now I can save up towards that fluid head for the tripod.

The Liquid Sculptures tone MP3 download is located at the bottom of this page.

It has been quite some time since my first post about Liquid Sculptures. If you need a reminder, it was all about creating images like this one below, titled “Bang!”.

Bang!

At the time I had built a tone generator which created a constant-tone sound wave that was amplified and pumped through a speaker. This tone would vibrate a rubber membrane stretched across the speaker to propel drops of liquid into the air. Once the liquid is airborne, it can be photographed, freezing the droplets in mid-flight. This is what I will refer to as liquid sculptures – not a term coined by me, but widely used to describe this form of photography.

In the initial post, I realised that I had over-engineered the solution and there was a much simpler way which was far more accessible to the average tinkerer. (Read the blog post here http://pixelsrc.com/design-deploy-do/)

The original tone generator was too complex as a weekend electronics project. It was also only capable of generating a single tone without the lead-in tones as described later in this post.

The revised approach was to get everything that I required for the tones down on CD as an audio file which could then be played back again and again. Repeatability is key in this context.

The easy way to do this would be to generate the tone in an application such as Audacity (Free Open Source audio editor and recorder: http://audacity.sourceforge.net) and save the audio file to your computer and eventually burn it to CD. This makes the solution far more accessible as we probably all have access to a computer to play a digital audio file or a CD player to play an audio version.

This also allowed me to add a couple of steps which I previously could not, if I had continued to use the tone generator electronics circuit. I could now include a countdown on the left channel and the liquid sculpture tone on the right channel. Bingo!

This is the basic schematic.

A screenshot of the tone project as it appears in Audacity is depicted below. Click on this image to view an enlarged version.

This started out as a stereo project and that can be seen in the 2 channels on the Audacity design surface. The upper channel is the left audio channel and this contains a few beeps to audibly guide the photographer like a metronome would guide a musician. This helps you anticipate the start of the constant tone that drives the liquid sculpture. The combined track consists of a long 1-second tone, followed by 3 identical, short 50 millisecond beeps which beep on the second (think of these as the countdown: 3, 2, 1) a fourth beep of a different tone denotes the “Go!” signal. All this takes place on the left channel which does not drive a rubber membrane.

The right channel (the lower of the 2 channels in audacity) remains quiet during the countdown and coinciding with the “Go!” signal from the left channel, a constant tone is pumped to an amplifier which drives a 120mm 8Ohm audio speaker.

A sample of this tone can be previewed in the YouTube video below: 5-second lead-in followed by a 100 Hz constant tone (PLEASE MAKE SURE YOUR COMPUTER AUDIO VOLUME IS TURNED DOWN BEFORE PLAYING THIS CLIP, AS I CANNOT BE HELD RESPONSIBLE FOR ANY HEARING DAMAGE AS A RESULT OF HEADPHONES AND HIGH VOLUME LEVELS, ETC)

I subsequently discovered that the stereo channels can be merged down into a single monophonic channel as the lead-in tones do not disrupt the liquid.

A few last tips before you download the MP3 tone and embark upon a journey of Liquid Sculpting.

1. Burn the downloaded MP3 file to a CD as an audio CD using your media player.

2. Rubber membranes – single layer of a large balloon (that is, cut it with a pair of scissors) or a latex swimming cap. Stretch this membrane across the speaker (not taut, but enough to smooth out any creases or wrinkles) and tape down the edges with gaffer tape or duct tape.

3. Calibration run – pour some liquid onto the membrane, turn the volume down and play the CD. Once the main tone starts, slowly increase the audio volume until the liquid goes from a vibrating state to an air-borne state. Do not turn the volume up to the max, as this will cause the liquid to instantly “take-off” in all directions.

4. Keep an absorbent cloth or towel handy to mop up any stray droplets which may land on your camera or lens (If this does happen, turn the volume down and/or move your camera back a little)

In ending, I would like you to have fun whilst capturing your liquid sculptures.

Click!
Chas.

Here is the audio file in MP3 format. Right-click and choose “Download linked file as” or “save as”.

Liquid Sculptures by Chas Venter.MP3

Please note that this “Liquid Sculptures – How To” by Chas Venter is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. Attribution to this work is required should you decide to use the MP3 in an educative context.

This was a really interesting exercise as it allowed me to convert existing BI systems to suite the new Enterprise System. Great opportunity and a nice learning exercise in the process.

Anyhow, now I am back (sure I have said that at least once before) and will try to get my virtual life back on track; Pixelapse dolly has almost died and all other projects entered a state of suspended animation. Time to turn the engines on.

Chas.

Version 1. A 2 metre Igus Drylin-W rail and glide, powered in a single direction by a “hobby type” motor and geared winch.

Version 2. Improved gear motor. Considered changing the winch setup to a serpentine belt.

Version 3. Moved from DC motor using PWM to a Geared stepper motor and serpentine belt,

Version 4. Geared stepper motor and synchronous belt.

This project only gets attention in-between a whole bunch of other tasks, so it progresses very slowly. When I get annoyed, it tends to get more attention as an outlet to blow off steam

Current progress:

5 May 2012.

Dolly and carriage working, platform powered by stepper working well.

Controller prototype box built. Contains Arduino Duemilanova with LCD and rotary encoder.

But that goes pear-shaped when you pop up the onboard flash. The shutter speed downgrades to a lowly 1/200 of a second. The little pop-up has serious limitations in this regard and is not capable of handling anything faster than that.

Upgrading to a beefier external flash yields the same lowly 1/200 of a second unless you enable the High Speed options in the external flash menu on the camera (Flash control > Shutter Sync > 1st Curtain  ..  2nd Curtain  ..  High Speed)

With High Speed enabled you can take shots at the shutter speed you chose, e.g. 1/8000 of a second and the high speed flash synchronisation will cope without any problems. During the exposure as the sliver of a shutter slides across the visual plane, the strobe will stutter multiple bursts to cover the entire sensor exposure.

Achieving higher speeds is possible, but not by adjusting your shutter speed. Adjusting the flash output power on the external flash unit.

Typically, your flash fires in full power (1/1) mode or as instructed by the camera. Turning the flash to manual mode from ETTL / ITTL and cycling through the manual power options gives you huge flexibility.

The manual modes allow you to specify the strobe power. The confusing thing here is that reducing the power, reduces the duration of the flash which equates to a faster shutter speed. Huh?

Let me explain. Inside the flash are a bunch of capacitors which can “store” a vast amount of power when the strobe is turned on (sometimes and typically on older strobes, you can hear a high pitched whine as the capacitors are charged up). When the strobe is fired, this electrical charge is dumped onto the Xenon gas tube in the  reflector and the “full” power is capable of energizing the Xenon gas for a duration of at least 200 ms. The excited gas emits a burst of light starting out on the blue end of the spectrum and as it fizzles out of power the colour spectrum of the excited gas becomes red before it dies out completely.

If you reduce the strobe power, you are in essence clipping the electrical discharge. The flash fires off but within 1/64 of the power used, the capacitors are blocked and the excited gas immediately dies out. This burst was substantially shorter than the 200 ms of the full power burst. There are many tables out there which provide  speeds and power output. Obtaining a burst of light for 1/32,000 second is achievable.

During the exposure, the studio is darkened and the shutter has been opened but as it is dark, no pixels are detected on the sensor. At the right moment, the strobe fires at 1/64 power which produces a burst of light that  lasts for approximately 1/32,000 of a second, freezing the motion.

Strobes capable of 1/128 power or less will achieve a faster burst.

I intend using this technique to capture some high speed shots I have planned.

Click!
Chas.

I wondered; how does one turn an unhappy customer into a happy customer? I can think of many ways, and once you have a happy customer, you will probably have a customer for life.

Let me tell you about my happy state. I have always been an early adopter of technology, most probably due to the fact that I come across many stunning examples of Hi Tech in the Information Technology arena. Call me a geek. But it is not about the gadgets, it is about the simplicity and more so when that technology is intelligent, functional, elegant and rolled into a single package.

Admittedly, we as a family have our fair share of Apple devices and we have very few issues, if any, with these items. That would make us happy customers, generally speaking.

In November, I received an email from Apple. Ok, not addressed just to me, but I would gather to all registered owners of iPod Nano 1st Generation – Very good reason to register your products! The email stated that some 1G iPod Nanos that were still in use could potentially develop an overheating battery problem during recharge and as such had issued a worldwide replacement program for this specific product. If your 1G iPod Nano was one of those affected, they would swap it out with a current model iPod Nano Touch 6th Generation. What did I have to lose? Well nothing much other than not being able to listen to my music, so I sent my trusty iPod Nano in as per the instructions on the website. I was told that it could take 10 weeks to sort out.

It has been just over 10 weeks and today I received an email to inform me that my replacement Nano has arrived and could be collected – hence my visit to the iStore.

Putting it into context:

a 4 Gigabyte iPod Nano (1st generation) purchased in 2005 for R1,600.00, used extensively for 6 years providing me with thousands of pleasant listening hours and replaced with an 8 Gigabyte iPod Nano Touch (6th generation) in 2012 valued at R1,500.00. Total cost to customer R0.00, Cost to Apple, hard to quantify, but I do know that I will always shop for Apple products before I consider anything else.

How cool is that? This is Superlative Customer Service in my book – how many companies would bother about a customer some six years later? Very few I would think.

If you have a 1st Generation iPod Nano then check out the Apple iPod Nano replacement program. It may just make your day.

Also on the Apple support pages, there is a replacement program for potentially faulty 1 Terrabyte hard drives in specific 21.5 inch and 27 inch iMacs.

So, back to the troll in the store, I hope for his sake, that he finds happiness – I know I’ve found mine.

Then and Now, 1st and 6th generations.

I have just typed this blog entry listening to INXS on my brand spanking new iPod Nano Touch. Here’s to the next six years baby, this is going to be a good ride.

Click!
Chas.

I had previously spent (wasted?) some time taking pictures of those elusive milk and water drops – you know the ones; a macro or zoomed-in shot of a single drop of liquid colliding into an immovable object, like a black plate or plunging into a glass of similar liquid. In both cases the resultant images can be stunning if you succeed in capturing them, which wasn’t as easy as I had hoped – I was relying on my ability to count to three, synchronising the splash visually to trigger the shutter release cable on the third splash.

A lot was learnt. apart from the tripod, backdrop and strobe setup. The camera needed to be in full manual mode to reduce the amount of time required for taking the shot, that is, I didn’t want the camera trying to waste precious time and gauge the light intensity, or choose the best aperture for the light conditions, etc. Setting all the variables with fixed values was the best approach. Aperture nice and small (F16), White Balance set to Flash, Quick shutter speed with flash on first curtain and many other settings. I captured many throw-away shots where I either triggered the shutter too early or way too late, I did however capture a few shots but nothing spectacular. Here is an example of a water drop in the post-impact stage where the miniature column has pulled apart into three smaller drops.

[singlepic id=153 w=320 h=240 float=none]

The most important thing I learnt during this was that capturing the moment of impact was not that easy. Not if I was to rely on my oh-so-quick reaction times.

Back to Maurice’s website. Maurice’s project triggers a strobe based upon one of two sensors; light in the form of a laser disrupted by an object passing through the beam and sound picked up by a microphone and amplifier. I am more interested in the laser-based sensor at this stage as I just so happen to have one lying about in my electronics storage bin.

I must mention that all the heavy lifting for this project has been done by Maurice and I am only interpreting his work here. Kudos to Maurice, please visit his website.

Whilst there are a few electronic components and some soldering or breadboarding required, the guts of this project are driven by the mighty Arduino - an open-source electronics prototyping platform.

I modified the diagrams and source code to suite my needs and have included that info below.

The Arduino interface consists of three devices. The laser is a 5V Quarton (VLM-650-01), 4K Ohm Light Dependent Resistor and an Opto-isolator (Toshiba P521 4-pin). The LDR and Opto devices need resistors for pull-up or voltage limiting purposes.

Basic connection to the Arduino.

Laser: Polarity is important here with the black wire to the Arduino’s GND pin and red wire to Digital Pin 5. This component has a 5V upper limit so no resistors are required. Connected to a digital pin as it will either receive a low signal (0V) or a high signal (5V).

Light Dependent Resistor: This device is in essence a resistor but is affected by any light that falls onto it’s surface. The laser will be pointed to shine on the LDR. You can expect to obtain a reading of around 1000 when the laser shines on the LDR and a reading of 0 or close to it when the LDR is in total darkness. The LDR reading could drop well below 950 when the laser beam is interrupted momentarily.  The LDR needs to be connected to the 5V pin, Analog Pin 0 and a 10K Ohm resistor between GND and Analog Pin 0.

Opto-isolator: This 4-pin Integrated Circuit will fire the strobe. The opto-isolator is a sealed light-proof device which contains 2 internal circuits; the one circuit is a small LED illuminated by pins 1 and 2. The second circuit on pins 3 and 4 acts like the LDR described above and will “switch” on when the first circuit is active. Because the first circuit contains a small LED, it requires a resistor to prevent the Arduino from burning out the LED. The 50 Ohm resistance was calcuated using this LED calculator and filling in the values from the data sheet of the P521 opto-isolator.

The components were tested on a breadboard and then transferred onto a veroboard/stripboard circuit.

Please note the 2 breaks in the circuit under the P521 opto-isolator located at the bottom of the circuit.

The completed circuit was shoehorned into a small component enclosure. Click on the image for a large version.

The Arduino code is relatively simple, but needs to be tweaked to obtain the best performance possible. Currently the code consists of the following:

// Digital pin assignment
#define LASER_PIN 5 // Orange wire on D5
#define STROBE_PIN 4 // Blue wire on D4

// Analogue pin assignment
#define SENSOR_PIN 0 // Green Wire on A0

// Laser beam disruption threshold
#define LASER_THRESHOLD 950

// Flash PC-SYNC duration
#define STROBE_DURATION 100

void setup()
{
 pinMode(STROBE_PIN, OUTPUT);
 digitalWrite(STROBE_PIN, LOW);

 pinMode(LASER_PIN, OUTPUT);
 digitalWrite(LASER_PIN, HIGH);

 delay(200);
}

void loop()
{
 int laserVal; 

 laserVal = analogRead(SENSOR_PIN);
 if (laserVal < LASER_THRESHOLD)
 {
 digitalWrite(LASER_PIN, LOW);
 digitalWrite(STROBE_PIN, HIGH);

 delay(STROBE_DURATION);

 digitalWrite(STROBE_PIN, LOW);
 digitalWrite(LASER_PIN, HIGH);

 laserVal = 1024;
 delay(10);
 }
}

These are the sample images covering the manual strobe mode from full power down to 1/64th power. Notice how the decreasing power of the strobe affects the duration of the strobe and therefore creates a crisper image as far as freezing the motion is concerned. In all shots below, the shutter duration was 2 seconds and in complete darkness. Disrupting the laser beam fires the strobe at the specified power setting. The small plastic container was dropped from approximately 10 centimeters above the laser beam.

Full power strobe

1/2 power strobe

1/4 power strobe

1/8 power strobe

1/16 power strobe

1/32 power strobe

1/64 power strobe

My next task is to introduce a potentiometer into the circuit so that I can dynamically adjust the duration to wait before the strobe is fired. This will cater for finer control to catch the drops on impact. Watch this space.

Click!
Chas.

This doesn’t necessarily mean that everything you tackle needs to be endlessly redesigned and redeployed. If you are satisfied with the experience of the “Do” phase, then no further work or effort is required. If however you discover gaps or inconsistencies, then revisit Design. Deploy. Do.

I embarked upon a Liquid Sculpture project recently which had an overly complex electronics component. I intended publishing  the project and whilst it was acceptable for my purposes, it would not have been the case for many people wishing to build the project for themselves.

The schematic above forms the “engine” for liquid sculpture images and was pretty linear and simply, or so I thought. Reading from left to right; the input voltage is 12 V and undergoes some regulation to eradicate any ripples in the power. This drives a function generator (a.k.a. signal or tone generator) which is capable of generating a constant tone in the 10 – 10,000 Hertz frequency range. For liquid sculptures a tone in the vicinity of 80 Hz is ideal. A tone of 10,000 Hz is just an ear-piercing siren-like noise and would appear to be useless for my purposes. The generated tone could either take the form of a sine wave, square wave or sawtooth wave. Where the sine wave tone is acoustically consistent and the other two waves are just plain noisy. The tone frequency (Freq) is governed by a potentiometer (like a volume control) and there was no real way of knowing the exact frequency being generated and it boils down to the tone sounding correct or not. The tone output goes through a pre-amplification stage to bump it up in intensity using another potentiometer (Power) which provides the input into a pure power amplifier. The output from the amplifier block drives a 65 Watt 4 Ohm audio speaker (round shape with a diameter of 120 mm)

I created a breadboard prototype and the cost of components was not excessive and would have ultimately required a circuit diagram for a stripboard or a custom PCB. As electronics is not my forté (I develop Business Intelligence solutions) and although I can get myself around most basic electronics, I would not be comfortable providing a circuit that could in theory cause problems or failure for anyone who tackled the project.

The prototype from my initial design was used to take this image.

Bang!

There were a few problems with this design. Triggering the camera and strobes had to occur simultaneously with the generation of the tone. It was hard to recreate a specific tone if the “Freq” potentiometer was adjusted or if you set up the gear again after a few days.

Considering “Design. Deploy. Do” I realised that my approach needed to be simplified.

I decided to do the following; Forget about generating a tone using a function generator, and create MP3 files for the selection of tones I required. This made the entire process a lot simpler. Now I can burn the audio copy of the MP3 files to a CD. I can reserve the Left channel for a countdown leader (three beeps spaced one second apart, or even a verbal “3, 2, 1, Go!” sequence) and reserve the Right channel for the frequency burst to drive the liquid sculptures. The schematic below shows the simplification where the audio source (CD, MP3 or computer) drives the power amplification and the stereo output channels. This way I can recreate the sound sequences repeatedly and weeks apart at that.

I have also decided to upload the MP3 files for anyone to use (find them in the store link in the next few days)

Here is sample of the liquid sculptures using the MP3 method – Not that the result  would be any different, it just makes the manual timing for triggering the shutter or strobes so much more easier – more about this in a moment.

Bang2!

Some helpful suggestions:

1. It is possible to shoot high speed with an external strobe in ETTL or ITTL mode (right up to 1/8000th of a second in some cases).

2. But as all the action takes place in the first few 10th’s of a second, it might be beneficial to engage mirror lockup so there is less to do at the point of taking the shot.

3. Work in Manual Mode. Manual Focus is required so that the camera doesn’t move from the focus point that you chose and similarly for aperture, white balance and ISO. This is less for the camera to do and goes a long way to helping you catch the action.

4. Shallow depth of field occurs at the large end of the aperture range so choose smaller apertures (F16 perhaps).

5. Consider triggering the strobe in manual mode at 1/128 or 1/64th of a second to shorten the duration of the exposure. A standard strobe fired at 1/64 is equivalent to a shutter speed of approximately  1/32000th of a second – You’ll need to be shooting in the dark for this to work with the shutter wide open.

I will be covering this project in more detail in the weeks to come. Ultimately I would like to incorporate an Arduino solution into the project to help trigger and control the devices required.

More, later.

Click!
Chas.

Bang!

Setup as follows:

Camera on tripod with shutter release cable and off-camera flash.

Speaker enclosure (driver facing upwards) with red silicon rubber sheet stretched over the speaker driver opening.
Circuitry set for low resonance (approximately 10Hz). Drops placed on silicon rubber.
Power switch connected to “push to make” press button switch.

Camera shutter release and function generator switch pressed simultaneously.

Bang!

Creds to FotoOpa (I believe that’s Danish for Photo Grandpa / Oupa) on Flickr for the inspirational “water sculptures”.

I’ll follow this up with a more in-depth tutorial.