Continouus shooting with 3D stereo possible?

mr.burns

223

Continouus shooting with 3D stereo possible?

« on: 03 / October / 2016, 07:02:14 »

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Dear all,

I want to know if it is possible to use CHDK to shoot 3D stereo photos with continouus shooting mode.
Lets say I want to shoot my family on a party. After shooting photos I often see that some people on my photos have closed eyes, or they look not good, etc..
In 'normal' 2D photography I use the continouus shooting mode of the camera which shoots 3-5 photos in a short time.
Later I can choose the photo which is best of the 3-5 photos.
The same I want to do with 3D stereo photos. I use the USB cable to shoot syncronized photos.

- How can I use continouus shooting for 3D stereo in CHDK?
- Should I use a script? Which One?
- Or do I need a mikrocontroller which triggers the USB shutter in short interval?
- Or do I use the camera built in continouus shooting mode enabled in both cameras?
- What about the synchronisation of the the 2nd, 3rd, 5th photo - is it as good as the first photo when I trigger the USB-shutter?

Thanks...

« Last Edit: 03 / October / 2016, 07:05:49 by mr.burns »

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2 x Powershot S110 103a

waterwingz

12139

Re: Continouus shooting with 3D stereo possible?

« Reply #1 on: 03 / October / 2016, 08:29:11 »

Quote from: mr.burns on 03 / October / 2016, 07:02:14

How can I use continouus shooting for 3D stereo in CHDK?
Should I use a script? Which One?
Or do I need a mikrocontroller which triggers the USB shutter in short interval?
- Or do I use the camera built in continouus shooting mode enabled in both cameras?
- What about the synchronisation of the the 2nd, 3rd, 5th photo - is it as good as the first photo when I trigger the USB-shutter?

I think you can get this to work but it might be tricky. In order to get good synchronization, you will most likely need to use some external electronics like a microcontroller though.

If you simply trigger the first shot with a USB remote cable and the remote sync function is enabled, then the subsequent shots will be blocked as they will wait for the next "sync" signal. So you need something to re-trigger the next shot. You could do it by pressing the remote switch multiple times, or you could use a microcontroller, or maybe even a simple 555 timer chip circuit.

Note that you don't need a script to do this - the built-in CHDK USB remote functionality is sufficient.

One word of caution - it's possible that CHDK for some cameras might not sync in continuous mode if the USB remote hook is in the wrong spot. You can test this by putting the camera in continuous mode, enabling USB remote sync'd shooting, and observing if the camera halts after each shot until the remote is pressed again.

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Ported : A1200 SD940 G10 Powershot N G16

mr.burns

223

Re: Continouus shooting with 3D stereo possible?

« Reply #2 on: 03 / October / 2016, 12:48:20 »

Hi waterwingz,

thanks for reply.
Lets say I will use a microcontroller to tigger the USB 2 times after I initilaize the shooting by my finger.
The 'Switch types' in the remote settings I set to 'One touch', I set 'Enable sync' to true and 'Control modes' to 'normal'.
Then I press the USB-button with my finger to focus, initialize exposure and flash settings of both cams.
Then I wait for the 'Beep' of the cams which will let me know cams have focused now and I release the finger to take first photo.
This will trigger the microcontroller which will initialize the next 2 shots. But here my problem comes.
The microcontroller gives 5V to the USB to initialize the 2nd shot, this is the 'half press' signal for the cam to do focusing again.
But how should the microcontroller detect that the cams have finished focusing (like me I am waiting for the beep)?
Best would be I only focus manually for the first shot and then use the microcontroller to immediately shoot the subsequent photos without waiting the cams to focus again.
But I do not really know how to get this. Can I just set the USB to 5V and after e.g. 10ms to 0V again to trigger the subsequent shots without waiting for the cams to finish focusing?
Basically I want to focus only on the first shot if I trigger the cam by my finger. Then the microcontroller should trigger the subsequent shots immediatly (with same focus setting as from 1st shot) without waiting for the cams to finish focusing again. How I can get this?
Hope you get what I am thiking here ;-)

« Last Edit: 03 / October / 2016, 12:50:29 by mr.burns »

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waterwingz

12139

Re: Continouus shooting with 3D stereo possible?

« Reply #3 on: 03 / October / 2016, 13:20:37 »

Quote from: mr.burns on 03 / October / 2016, 12:48:20

Best would be I only focus manually for the first shot and then use the microcontroller to immediately shoot the subsequent photos without waiting the cams to focus again. But I do not really know how to get this. Can I just set the USB to 5V and after e.g. 10ms to 0V again to trigger the subsequent shots without waiting for the cams to finish focusing? Basically I want to focus only on the first shot if I trigger the cam by my finger. Then the microcontroller should trigger the subsequent shots immediatly (with same focus setting as from 1st shot) without waiting for the cams to finish focusing again. How I can get this?

I think this is going to need a script. Something to trick the camera into thinking the shutter button is being held down so that it will shoot continually (with the camera set in Canon Continuous mode) while actually allowing the USB remote signal to "sync" each shot.

I'll take a look and report back later.

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mr.burns

223

Re: Continouus shooting with 3D stereo possible?

« Reply #4 on: 04 / October / 2016, 11:08:48 »

Hi,

I am thinking to do it the way as shown in the attached image, the steps here as follows:
('Switch types' = 'OnePush', 'Enable sync' = true, 'Control modes' = 'normal')

1.
I trigger the button T1 and wait for the cams to finish focus (green leds on)

2.
I release the button to do the first shot

3.
The microcontroller initiates 3 subsequent pulses.
pulse width: 50ms, pause between pulses 200ms

The only question is:
The pulse width is too short to finish focusing for the subsequent shots.
Does that mean the cams will keep the focus from 1st shot? Or does CHDK reset the focus for each pulse and the subsequent images are unsharp?

ContShoot.jpg (55.52 kB, 1016x1024 - viewed 37 times.)

« Last Edit: 04 / October / 2016, 11:13:03 by mr.burns »

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waterwingz

12139

Re: Continouus shooting with 3D stereo possible?

« Reply #5 on: 04 / October / 2016, 14:52:46 »

Quote from: mr.burns on 04 / October / 2016, 11:08:48

The pulse width is too short to finish focusing for the subsequent shots.

If the cameras are setup for normal shooting, you'll not likely get more than one shot every two seconds using your setup.

Is they are set into continuous mode, the circuit you have drawn will not work as each USB pulse will effectively reset the continuous shooting process. With the additional focus and exposure time delays you have mentioned.

To make your circuit work properly, you will need a script running on each camera doing the sequence I described in my earlier post. I'll try to post an example script tonight.

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Ported : A1200 SD940 G10 Powershot N G16

Kasius Klej

30

Re: Continouus shooting with 3D stereo possible?

« Reply #6 on: 04 / October / 2016, 15:25:48 »

Quote from: mr.burns on 03 / October / 2016, 07:02:14

- How can I use continouus shooting for 3D stereo in CHDK?

You press both shutters simultaneously and let the script do the rest.

Quote from: mr.burns on 03 / October / 2016, 07:02:14

- Should I use a script? Which One?

Should be a script something like

pause 1 rem suppose first pause gives cameras time to focus
shoot
shoot
shoot
pause 2 rem and here you have 2 sec time to yell hold still to the party
shoot
shoot
end

...theoretically.

Quote from: mr.burns on 03 / October / 2016, 07:02:14

- Or do I need a mikrocontroller which triggers the USB shutter in short interval?
- Or do I use the camera built in continouus shooting mode enabled in both cameras?

You don't need the micro controller.

Quote from: mr.burns on 03 / October / 2016, 07:02:14

- What about the synchronisation of the the 2nd, 3rd, 5th photo - is it as good as the first photo when I trigger the USB-shutter?

It is as good.

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reyalp

14081

Re: Continouus shooting with 3D stereo possible?

« Reply #7 on: 04 / October / 2016, 16:49:39 »

Quote from: Kasius Klej on 04 / October / 2016, 15:25:48

Quote from: mr.burns on 03 / October / 2016, 07:02:14
- What about the synchronisation of the the 2nd, 3rd, 5th photo - is it as good as the first photo when I trigger the USB-shutter?
It is as good.

Sorry, but there is no way this can be correct. Without external synchronization, two scripts running separate cameras will get many tens if not hundreds of milliseconds out of sync by the first shot, and diverge more from there.

For stereo of moving subjects, you need to do much better than that, and it can be done using the USB remote.

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Kasius Klej

30

Re: Continouus shooting with 3D stereo possible?

« Reply #8 on: 04 / October / 2016, 17:35:53 »

Quote from: reyalp on 04 / October / 2016, 16:49:39

Quote from: Kasius Klej on 04 / October / 2016, 15:25:48
Quote from: mr.burns on 03 / October / 2016, 07:02:14
- What about the synchronisation of the the 2nd, 3rd, 5th photo - is it as good as the first photo when I trigger the USB-shutter?
It is as good.
Sorry, but there is no way this can be correct. Without external synchronization, two scripts running separate cameras will get many tens if not hundreds of milliseconds out of sync by the first shot, and diverge more from there.

Well in the case where one camera is 10% faster than the other, they diverge a hundred miliseconds in first second alone. But that should not be the case. Cameras should be about the same speed, so there'll be shots where they'll meet and be quite in sync.

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waterwingz

12139

Re: Continouus shooting with 3D stereo possible?

« Reply #9 on: 04 / October / 2016, 17:47:17 »

Quote from: Kasius Klej on 04 / October / 2016, 17:35:53

Well in the case where one camera is 10% faster than the other, they diverge a hundred miliseconds in first second alone. But that should not be the case. Cameras should be about the same speed, so there'll be shots where they'll meet and be quite in sync.

If you search this forum for the term "precision sync" you will find may posts reporting actual results with real test data. That data shows that two cameras that receive the same signal to shoot a single shot will frequently take hundreds of milliseconds different times to actually take the shot. There is a trick used in CHDK to more accurately sync the shots that may achieve 1 mSec precision most of the time but your described code sequence cannot use that trick.

So whether you believe that should happen or not, it does. The little microprocessors in these cameras are busy at times and thus take variable amounts of time to respond.

Edit : the main question posed in this thread is how to achieve precision sync (< 1 mSec) when shooting in continuous mode. I'll post how to do that with an external timing circuit (uController or a timer) and a CHDK script. I'd be happy to see someone find an easier way to do it.

« Last Edit: 04 / October / 2016, 18:10:52 by waterwingz »

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