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Description

This project provides software (and also hardware files) to build custom DSLR time lapse timer. Main aim is to provide more flexible timing possibilities for taking timelapses, long exposure photos and utilize features like e.g. BUP and so on. Timer shall work in the philosophy of "set and forget". Support set up of wake up alarm and various shoot modes.

Design

Why this design with many electronics? Lets have a look on that step by step:

Why RTC timer?

Sometimes is needed to postpone start of shooting time quite later. Unfortunately because whole device is powered by battery, also low power consumption is required during waiting for shot. This requirement is fullfiled by suspend AVR chip to low power consumption mode. Processor internal clock is stopped and can be wake up by one of two external signals dedicated for this purposes. One signal pin is connected to select button on case so you processor can be woken up by pressing button. Second is connected to external RTC timer alarm pin, so processor can be woken up when alarm in RTC clock chip is activated.

Next reason is accuracy. AVR 8 MHz internal clock is not so accurate. There is RC timer which is dependent heavily on chip temperature. Selected RTC clock is very stable and accurate, because it contain also temperature compensation. There is also date-time engine inside, so there is no need to do any calculation from date-time to RTC ticks counter and back. When time needs to be set, then chip simply receive time in format hour:minute:second day:mounth:year. Same situation is here also for alarm. This makes a lot of time user setting much more simple for implementation.

And thir reason is simple. DS3231 contain custom batery, which maintain clock even when main AA batteries are removed or when power switch is off.

Why Laser LED?

Most DSLR cameras shakes when mirror is flipped down and back when taking a photo. This little shaking is then visible in time lapse video. This can be filtered out when postprocessed by deshaker (e.g. by Deshaker in VirtualDUB). Unfortunately problem commes up when you try to make over night time lapse (e.g. time lapse of stars). In this case there are no fix points for software video stabilizer and deshaking fails.

For this purposes, there can be laser LED used, to make stable horizontal line on some object close to lower frame border. Stabilizer can use this line as stable point and line is then removed when video is converted from 3:2 to 16:9 ratio.

And laser also helps to focuss in dark when shoting on long exposure.

Why NRF24 module?

This is a little of thinking forward. My plan in future is also to build electronic time lapse stativ. There can be also some other photo-electronic utilities, which can benefit to communicate each other. So we will see ;-)

Wht IR remote?

Good question is why to use IR remote, when there is cable remote. This was just pragmatic decision. There is a lots of cable types for various DSLR cameras, and is not possible to create cable and connector for each of them. Also comunication with DSLR over cable can differ (some of them makes short against ground, some against VCC, some can use some special signal).

IR remote is more flexible in this case, because there is only one HW communication medium. Communication itself is driven by by software by tuning IR modulation frequency and protocol. With knowledge of this two parameters is possible to make remote for various DSLR manufactures without need to modify connector or cable.

Hardware

Hardware platform is based on following parts:

• Arduino Pro Mini - ATmega328 based board with 8MHz internal clock, without 5V stabilizer (to reduce consumption in sleep mode)
• NRF24L01 WiFi module - 2,4GHz wireless RF transceiver / receiver module
• DS3231 real time clock - high precision realtime clock timer
• 128x32 OLED LCD IIC I2C - small OLED display
• IR LED - usually 800nm - 900nm infrared LED diode working with your camera
• Cammera shooter connector - connector supporting connection with your camera (e.g. 3,5mm JACK for K5-II)
• Line laser diode - Line laser diode which can be used as flash or stabilization point maker when shooting timelapse in dark.

Hardware is connected according to following schematics (click here for large image):

Mechanics

As I'm not so skilled with hardware design, there is some basic case created

All 3D models are designed in FreeCAD and are stored in directory 3D. Parts are optimized for 3D printing and exported to OBJ format.

Current project status

Project is now in development phase. Hardware is tested and working with my Pentax K5-II (excluding RF24 WiFi module), but software is still not fully completed (just simple test version). However camera works either over jack or over IR.

Unfortunately I'm quite busy now so it seems that development will freeze for a while.