Instructables

Edit (3/29/2014): When I first posted this instructible earlier this month I didn't describe what I was going to be using this rig for or where my requirements were derived from, but now that I have gotten some film back I thought I would share.

I needed a way to take low volume high resolution photos of liquid rocket launches and static fire (hold down) tests in the Mojave desert. Last weekend was my first opportunity to photograph such tests with this wireless shutter release on my Pentax film camera and I was very pleased with the results. I have added a results section at the end of this instructable that reflects some of my lessons learned from that weekend.

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I needed to take high resolution photos remotely with my Pentax 645 medium format film camera. I could not find any off the shelf solution, let alone one that meet my requirements, so I decided to build my own.


Requirements:

  1. Triggered by a remote TTL level signal or a remote break-wire
  2. Wireless trigger range >100 ft. (expandable to 1000ft.)
  3. Robust method of serial communication to avoid inadvertent shutter actuations.
  4. Mount to camera in less than 30 seconds

Operation:

  1. A 2.4GHz xBee modem DIO pin changes state based on a user defined input
  2. The xBee modems are configured for DIO line passing, which sets up virtual wires between matching DIO pins on two paired modems, so when the DIO line on the remote node changes so does the matching DIO line on the camera node
  3. The output of the Camera node DIO line pulls a pin high on a simple microcontroller
  4. The microcontroller issues a command to a servo
  5. The servo depresses a shutter release cable
  6. The shutter release cable trips the shutter of the attached camera.

 

 
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mattthegamer463 made it!3 months ago

Inspired by this, but wanting to save money and simplify, I came up with what you see below. I used a $3.50 radio remote and receiver from eBay instead of Xbees and a latching relay and 555 PWM circuit to drive the servo to the correct positions. The latching relay is driven by a H bridge and the servo will hold position without power so for a ultra-long exposure you can actually turn the power off and save battery life. The range is a little short (only 20 feet right now) so I'm going to experiment with a external wire antenna.

temp_1701811506.jpgtemp_380147945.jpg20140827_161536.jpg
John Culbertson (author)  mattthegamer4633 months ago

Hey, nice build. I like that you added the ability to cut power to the servo, that is a shortcoming in my design, because my servo is always drawing a small amount of current.

Can you post links to the of the hardware that you used, specifically the radios.

Glad you liked it. I should say the servo power has to be cut manually, it's not a remote feature so it's less useful than you might be imagining. The receiver/transmitter modules are really cheap on eBay.  The shutter release cable is also really cheap and the spring can be removed to minimize the amount of force the servo has to exert. The latching relay could be any 5V single coil latching relay, driven by a H bridge.  The servo is just a regular junk one.

I attached the schematic.
Trigger Circuit.png

I love this, is there any way to pay you to make this for me?!?!

DarrenH11 month ago

I'm doing Digital Line Passing with Xbee. I followed your instructable and I cannot get output timeout to work correctly.

DO0 is connected in series to resistor->LED->GND. Setting DIO0 to 4 or 5 will not cause the LED to be HIGH in either setting until the monitor xbee line passes a HIGH. Is this right?

Also, the timeout feature does not work. Once the DO0 goes HIGH, it remains HIGH until the sensor xbee has LOW for DI0. Help?

Sensor: IR = 14, T0 = 15

Output Xbee: IR = 0, T0 = FF

John Culbertson (author)  DarrenH11 month ago

For the timeout feature try decreasing the T0 value on your output xBee it is currently set to 0xFF = 0d255 = 25.5 seconds, so if might be working fine it is just set so long that you are not seeing it.

As for setting DIO to default high I will look into it this week and get back to you. You could get around this electrically though by going 3.3v-> LED->Resistor->DIO0 and using the DIO pin as a sink instead of a source, that way when it is in its LOW state the LED will be on and when it is in its high state the LED will be off. I fairly certain you can use the DIO pins as a sink, but you should double check, and note the max sink current.

John Culbertson (author) 1 month ago

This is a reference on proper mounting on 1/4 wave monopole antennas, which is what the whip antenna on the xBee is. The reason I was not getting the maximum 300ft. range was because I was bending the antenna over, a practice that this reference warns against.

http://www.digi.com/support/kbase/kbaseresultdetl?id=2142

John Culbertson (author) 3 months ago

Was recently doing some Analog Line passing and this site was a useful reference for those who are interested:

http://www.etotheipiplusone.net/?p=748

Favorite quote: "Comparing 3.3v to #NaN always results in bullshit."

4DIY CHANNEL9 months ago

Check it out :)

mdickerson69 months ago
Also to drill a D shaped hole. Use the largest drill bit you feel comfortable with and place one hole in each rounded edge and get a 10 piece wood working set from a craft store. One is shaped like a pike it's great for shaping the edges and is sturdier than an exacto knife.
John Culbertson (author)  mdickerson69 months ago

Cool, I have heard of drilling the two holes and filing the remainder, but never using a wood working tool. I am curious, would it work on plastic, like I used for this enclosure?

mdickerson69 months ago
Holy cow! Amazing! Truly amazing!! I spilled my coffee all over the place... Anyway. What was the total cost of the device? And estimate of time spent?
John Culbertson (author)  mdickerson69 months ago

Thanks. This is on the order of a weekend project if you have all the parts.

6 hours programming and learning xBee line passing. My instructions should cut this down to 1 or 2 hours

8 hours of enclosure fabrication and soldering.

For cost breakdown:

$64 for the pair of xBee modems and adapters (look at step1 for much cheaper alternatives if this is out of your budget)

$10 Enclosure

$10 Servo

$20 cable release

$8 Trinket microcontroller

$5 Li-Ion Battery

$15 Ni-Mh battery

$0 Protoboard

$4 hot shoe to 1/4-20 adapter

$0 Misc. connectors and wire I had on hand

Total: $136

audreyobscura9 months ago

Wow! Awesome. Thank you so much for such a thorough build!

Also, I shoot with a mamiya 6x6 - i never thought of doing a mechanical shutter hack like this. genius!

John Culbertson (author)  audreyobscura9 months ago

Thanks! A little jealous of the mamiya.