Intervalometer/dither mechanism - working

[rcheshire (Rowland)]

The other thread is a bit old.

This is the project to date - images and below. Sorry removed videos - burning a hole in bandwidth.

The intervalometer variables at this stage are wake time, image number and exposure time, AF and/or mirror lock up if turned on, pause and automatic termination of the image session. Fairly standard.

EDIT: added a dark session via hardware switch - cuts out dithering. This can be limited to a reduced frame count.

A limitation of the program is that once paused the frame count begins anew and dithering starts all over again from where it left off.

The dithering mechanism is an add on - something I had to build - not sure how effective it will be, but it saves pushing buttons constantly for hours on end between shots.

Next job is to set up an imaging run - 40 jpegs approx 30 seconds each and see what adjustments are required to motor speed, which governs push button time.

EDIT: dithering works with some fine tuning.

Happy to post the code, parts list and the motor/optocoupler, shield pdf, or the eagle.brd file if anyone is interested.

[Poita (Peter)]

I'm definitely interested, post away!

[rcheshire (Rowland)]

I'm working on improving the code at the moment. Shouldn't be too far away. The rest piggy backs off an earlier project

The board, switch wiring, parts list, can be downloaded from here near the bottom of the page - leave out the limit switch on the wiring diagram.

The pcb board - the unipolar stepper part needs to be hacked to accommodate the optoisolator. Pin holes for Arduino pins 10 and 12 need to be joined and earthed - depends on the optoisolator.

Have a look at the Arduino pin out to see what I mean.

Please keep in mind this is very much at a hobby level and I have had to learn a whole lot of stuff to get it to work.

You'll need an Arduino... and the Arduino environment/tool chain. All explained on the site.

A limitation without the facility of an LCD and pushbutton setting (another project) is that new imaging session parameters must be uploaded as newly compiled code. That is, change frame count exposure time or wake time - recompile and upload (not sure if you are familiar with the arduino).

[Poita (Peter)]

I've been hacking away with the Arduino for a while, I'm no expert but know my way around.
Thanks for sharing, I just enjoy DIY stuff.

[rcheshire (Rowland)]

Here's a working sketch. A bit clunky in places, but effective.

It will do an imaging run - dither between shots - dark frames as required (version 2 does bias and flats too - under development) -override the image limit, which is set at 40.

The first four parameters sets the intervalometer parameters. Set motor steps and delays to suit.

Dither is a bit clunky but works driving a box spiral with RA and DEC

end of session goes into a while (1) - may have to reset the board to reactivate a session in that case.

For a 5d mkii 500 milliseconds is needed to lock the mirror up and settle to fire the shutter. 100 is sufficient for a 1000D. If lock up time is too short the shutter locks up but the shutter won't activate.

Have fun.