Automated DSLR (Pentax & Canon) imaging using apps

[cybereye]

Hi everyone!

I'm not sure if this was the right place to post this piece of information but it seemed more relevant here in Beginners Astrophotography rather than in the Astronomy App section.

One of the many issues I have using my Pentax DSLR is getting images that are always the same length of time. At the moment I have a little kitchen timer that I activate when I depress the cable release. When the timer "dings" I then stop taking the image.

Now, I'm also a member of the Pentax users forum and came across this Android app which allows you to set up an imaging run with a Pentax DSLR, more specifically those which have click-on, click-off, IR bulb settings like the K-x. ( http://www.pentaxforums.com/forums/pentax-dslr-discussion/131633-absurdly-simple-diy-k-x-remote-timer-using-mp3-player.html ) You can set the number of shots required, the exposure times of the images and a time between images. All that is required is a cable to be manufactured that plugs into the audio port of your Android phone. I've priced the IR LED's from Jaycar at $1.50 each. An old set of headphones should suffice for the cable. There is also a Canon iPhone app that does the same thing and is called "dslrbot" (www.dslrbot.com (http://www.dslrbot.com)).

How nifty are these apps!!

The other major problem I have is that when using the bulb setting the IR remote on the Pentax Km needs to be pressed for the complete length of time that you require the exposure length to be. Try holding a remote button pressed for 5 minutes while pointing it at the camera. Trust me when I say it can be a real pain in the hand!! Anyway I've gotten around this problem by having a friend make a bracket which holds a manual cable release over the shutter button. Now I just press and lock for the required time. However I've asked the developer if he could adjust the app to suit the Km as well and it is now in the pipeline.

Anyway, I just thought those who use DSLR's might be interested in this information.

Cheers,
Mario

[luigi]

This?
http://cgi.ebay.com/Timer-Remote-shutter-Pentax-K-m-K20D-K10D-K200D-K100D-/260583049128?pt=Camera_Camcorder_Re motes&hash=item3cabf5c7a8

[cybereye]

Luigi,

This remote is a cabled one. Unfortunately the Pentax Km, and I think most newer Pentax cameras, does not accept a cabled remote, only IR, despite what the ebay description says.

Thanks anyway,

Cheers,
Mario

[cybereye]

A quick update...

On the weekend, using a piece of freeware called Audacity, I was able to replicate the signal that would initiate the bulb setting by IR remote control on my Pentax Km.

The only things I needed to buy were 2 IR LEDs which cost a total of $2.50 from Jaycar. I had an old audio extension cable at home which I modified with the LEDS and this cable now plugs into the earphone socket of my phone. I have 3 different wav files for 1, 2 & 5 minute exposures as well as one for a simple shutter release. I just play the corresponding wav file for the length of exposure that I require and away goes the Km, capturing all those elusive photons!!!

I tested it last night and it worked a treat. Unfortunately PHD guiding decided to play silly buggers so I have no decent images to share!!

Cheers,
Mario

[arifmshaikh]

Hi Mario,

I just checked with Jaycar and they only have 5mm infrared LEDs not the 940nm which is mentioned on the dslrbot website. The salesman did not understand what nm means. Could you please let me know which IR LEDs can I buy?

Thanks

[MrB]

I am not surprised.
That is the exact reason I left the company... they pay peanuts and therefore employ monkeys.
Do not be surprised if Jaycar is as useless as Dick Smith in the next few years... it's almost there already.

[rcheshire]

Good old Audacity - I must go looking for Android apps for canon.

[cybereye]

The 940nm refers to the wavelength of the IR LED and not the size. I tried getting clear LEDs as per the instructions but Jaycar at Underwood in Brisbane only had blue coloured ones. I asked what the difference was and all I got was a shrug of the shoulders and a "I don't know." from the salesman.

I took the risk of spending $2.50 on the blue ones and they worked with my Pentax. I still don't know what the difference is except the colour of the plastic!! I suspect they would work with a Canon as well. The big thing is making sure you know which is the positive and which is the negative lead on the diodes. I was told the long lead was the positive one.

The 5mm is the physical size of the LED.

I hope this helps,

Cheers,
Mario

[MrB]

Mario.. I believe the blue tint on the emitters is only to distinguish them from the clear visible led's.
If you picked up a clear led, applied power and no light was emitted.. you'd probably think it was dead and throw it away.. if the LED has a blue tint.. you think.. oh it's IR.. keep that.
Thats what I used to tell customers anyway ;) But i cannot think of any other reason.

The deep blue tint on the IR diodes is another matter, it acts as a filter.
There may be some filtering of the emitters too as they are not monochromatic, but I doubt it.

Yes the long lead is the positive (Anode) but it is not a good way to identify, as the leads do get cut.
There is also a small flat on the body of the LED, this is to identify the Cathode(negative) when the leads are cut.
You may also note that internally.. the cathode has more 'meat' than the anode.

EDIT: picture speaks a thousand words...http://en.wikipedia.org/wiki/File:LED,_5mm,_green_(en).svg (http://en.wikipedia.org/wiki/File:LED,_5mm,_green_%28en%29.svg)

[arifmshaikh]

There was only two types of LED at Jaycar. Blue and Transperant. I asked the salesman and he did nto what the wavelength of them. I ended up transperant one and tried. But no luck. So may it is not a 940nm. So I might have to try another one. You can test the IR led whether it is transmiting single by placing in front of your webcam.

[cybereye]

Arif,

Did you have two IR LED's hooked up as per the instructions? It needs two to work.

Cheers,
Mario

[arifmshaikh]

I went to Jaycar and he changed the led to the correct one(5mm 940nm), but it still does not work. I checked them with web cam and both leds transmitting the signal. It might be possible that it does not work with Canon 400D.

[cybereye]

Arif,

Unfortunately I can only vouch for the Pentax version.

You could try sending a message to the author of DSLRBOT to see if he has any advice.

Cheers,
Mario

[arifmshaikh]

I just realised that I was using 22KHz file rather than 38KHz. I tried to convert some music file but there is no option of 38KHz. Can you please send send me 38KHz file to arifmshaikh@yahoo.com

Thanks

[cybereye]

Arif,

You create a file that has a 19KHz signal on one track and an inverted 19KHz signal on the other track (stereo). That is why you need two IR LED's. When one is off the other is on and this gives you a 38KHz signal. However you also need the specific pulses for the Canon which I don't have - I only have the Pentax one.

Try www.dslrbot.com as their app should have everything you need - you only need to create the cable as per the instructions.

Cheers,
Mario

[arifmshaikh]

Hi Mario

Thanks for your advise. I contacted the dslrbot suppor and they will make a trial app in few weeks. So till that time I can just wait.

[KenNo2658]

Hi Guys, should point out that I am very much an Newbie here and to Astronomy, but I registered because I have a tip that might help here. If you go to Jaycar for anything and they cannot tell you about it, ask them to look up the spec sheet for it. I actually did that today for some red LED's I bought to illuminate my veiwing area so my wife won't trip over when bringing me my coffee. :eyepop: That will give you the frequency of the LED, as well as the Voltage drops and current ratings (the stuff I needed)

Feel free to ignore me if you like, as I said, I'm just a Newbie!

Ken

[cybereye]

Ken,

I'm always willing to take advice and always happy to welcome a "newbie" to IIS and astronomy!!

Cheers,
Mario

[MrB]

Hiya Ken, welcome to IIS :)

If you tell a Jaycar employee that you want some LED's, they should be reaching for the catalogue and turning to that page before you've even finished asking. I used to push my staff to always consult that chart with customers. Sadly, most Jaycar employee's can't even work out the value of the current limiting resistor for a particular LED.
Unfortunately.. Jaycar, and all retail in genereal, doesn't pay well enough to attract and retain employees with brains and knowledge of their product.

[KenNo2658]

Thanks for the welcome, Mario, Simon.
Hope I can be of some use here,

Ken

[alistairsam]

Hi Guys,

I went through this thread and wanted to ask if you'll have thought of using 555 timers or simple $2 microcontrollers to do what you'll need?

i can easily assemble one and send it if you'll like, that is if i've understood the requirement correct.
just need to understand what you're trying to do.

you need to send a modulated IR beam for 5 minutes or whatever duration you like?
does this need to be modulated at 38Khz?

its quite easy to make a small circuit with a 555 timer or a picaxe microcontroller that keeps the IR LED "high" so it transmits, and after the duration, it toggles it low so its off.
it can also be modulated at 38Khz.
but i'd need to know some IR signalling details for the canon or pentax. should'nt be hard.

it can be done with a simple one button switch. you can also add a dial that adjusts the time interval and if you like, a small display with the time as well.

let me know if anyone's interested and i'd be happy to send one free.
I have most of the components already.

I cant test it as i only have a canon 1000d that doesnt have IR.

but I must say, using an audio file is ingenious.

as for IR LED's, rsonline is a great source of these components, and their postage is free in Aus.

http://australia.rs-online.com/web/search/searchBrowseAction.html?method=retr ieveTfg&binCount=31&Nty=1&Ntx=mode%2bmatchallpartial&Ntk=I18NAll&Ne=4294960157&Nr=AND%28avl%3aau%2csearchDiscon_au %3aN%29&N=4294585528&Ntt=940nm+led

I only go to jaycar if i cant find the component here or on element14 or if the price is higher.

[cybereye]

Wow, this is getting better!!

For the Pentax, the IR signal to trigger the shutter is a pulse that consists of a 13ms 38Khz signal, followed by 3ms of silence then a group of 7 1ms on, 1ms off, 38Khz signals. (See the attached graph). I then played around with that pulse and discovered that if I then repeated it over and over again with a 100ms block of silence in between each group I could keep the shutter open indefinitely.

Does that make sense?

Cheers,
Mario

[alistairsam]

Hi,

I will do some tests and get back in a few days.
should be possible with a microcontroller.
I read that the philips code on universal remote controllers can also control pentax cameras.

[arifmshaikh]

I found the correct LEF from Jaycar and made the trasnmitter. I also got the trial version of DSLRBot from the developer and installed in. It works only couple of times when I tested with my Canon 400D. I don't know whether the the headphone cable I am using is not good or this application does not work well with this camera.

[cybereye]

Arif,

Make sure the volume is at maximum - I've been caught by this a couple of times!!

Cheers,
Mario

[arifmshaikh]

Mario,

It does not work well even with high volume. I checked the settings for iTune and made the changes as mentioned on the DSLRBOT site, but no luck. I am happy with wireless remote bought from ebay, it works perfectly even pressing from the side.

Regards