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Arduino intervalometer for Digital Cameras

2015-01-18 09:39  
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Arduino intervalometer for Digital Cameras

This intervalometer / remote timer has been built and based on code kindly provided by “the roaming drone” and then modified:). The main function of this intervalometer system is to allow automated exposure control of the camera using the bulb mode by varying the length of the control pulse that keeps the shutter open using an external light sensor to calculate the correct camera settings. When used for time lapse photography it should minimise the dreaded flicker that occurs when Av or TV modes are used to adjust the exposure over a long time lapse sequence.

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The Box

As the system is based on the Arduino mega microprocessor I decided to expand the options available to me by including the Toas TSL230R IC for exposure control using bulb and iso ramping and the DS1307 RTC for pre-programming a shooting sequence. The automated bulb ramping and iso ramping functions are being developed to cater for the lighting changes that occur during dawn and dusk without manual intervention so that the shutter speed and iso settings can be adjusted together without changing the exposure.

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The in’s and out’s

Reprogramming the Arduino allows me to do pretty much anything I want with my cameras so I’ve no doubt it will be used for a lot of projects.A simple ramping intervalometer programme can be found here

The code is written to avoid any delay() type functions so it is non-blocking and the keybuttons remain fully functional even when the camera is being controlled.

Currently the box is programmed to control the Camera shutter and focus functions, it has a feedback circuit triggered by the flash socket on the camera which confirms the camera fired. It can manually or automatically vary the shutter speed in bulb mode from as little as 60 milliseconds to days.

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I won’t even begin to describe how the dynamic exposure metering works but would highly recommend Chris’s website for a wealth of information.

Inside the aluminium project box:

§  An Aduino Mega microprocessor.

§  A 2200 mAH rechargable lithium battery for standalone use.

§  A DS1307 RTC (real time clock).

§  ATaos TSL230R frequency to light convertor IC
that handles the exposure control.

§  A 20 x 4 backlit LCD display.

§  5 momentary push buttons

§  A green ‘shutter open’ led

§  A lot of wire and stuff.

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The Taos TSL230R IC

The basic interface to the camera shutter and focus using 4N35 opto isolators to remove any possibility of unwelcome voltages getting into the camera.

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Typical interface using the 4N35 opto isolator

Things to do:

§  Improve the user interface and the GUI.

§  Develop the bulb ramping and iso ramping process to allow the system to adjust the exposures during sunsets and sunrises.

§  Interface the Arduino to a netbook so the DSLR Remote Pro library can be used to adjust camera parameters, again without touching the camera.

§  Add HDR functionality for bracketing photographs across the boundary of 30 seconds. i.e avoiding the need to touch the camera to switch from manual to bulb modes.

§  Add the schedule programmming for non-attended shooting.

§  Sort out a method to retain the last user settings in the EEPROM memory