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Synch settings get lost (SDM 1.81)

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Offline mr.burns

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Re: Synch settings get lost (SDM 1.81)
« Reply #20 on: 03 / November / 2009, 12:38:59 »
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Hi,

yes I monitor the internal shutter for release! And like I posted, the code detects the release correctly.
But I wonder why you recommend to add a delay after releasing shutter button?
The 'normal' wait_until_remote_button_is_released function does not have a delay after releasing usb switch?
So why a delay for shutter button but not for USB switch?



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Offline Microfunguy

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Re: Synch settings get lost (SDM 1.81)
« Reply #21 on: 03 / November / 2009, 12:41:05 »
Quote from: mr.burns on 03 / November / 2009, 12:38:59

The 'normal' wait_until_remote_button_is_released function does not have a delay after releasing usb switch?

Yes it does, it has the exact code I gave you above.
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Offline mr.burns

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Re: Synch settings get lost (SDM 1.81)
« Reply #22 on: 03 / November / 2009, 13:00:41 »
OK, I will check...
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Offline mr.burns

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Re: Synch settings get lost (SDM 1.81)
« Reply #23 on: 03 / November / 2009, 13:35:52 »
Hi Microfunguy,

thanks exactly that solved my problem! Great!

>Remember, if conf.synch_enable is false, which it normally is if you  have directly pressed the shutter >button, all the above keyboard code will be ignored.

I already commented the line out which causes the synch_enable to be resetted (as you posted in one of your prevous messages), so it works fine now!

I want to know more details about the SDMs synch process (may to test/optimize for higher shutter speeds).
It would be great if you can explain more detailed how it works?

Why the left cam shows Synch:0.0000 and the right shows Synch:0.0040?
Where this 0.0040 comes from? Is this a config setting? Why the right cam has this delay and the left does not?
What have conf.synch_delay_value and conf.synch_delay_coarse_value to do with it?

If you find some time, may you can explain more detailed what happens in left and right cam after clicking the shutter button.
The more I understand from the process I can give also support for SDM with my ideas and programming knowledge.

Thanks for support!

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Offline Microfunguy

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Re: Synch settings get lost (SDM 1.81)
« Reply #24 on: 03 / November / 2009, 13:55:24 »
Quote from: mr.burns on 03 / November / 2009, 13:35:52
I want to know more details about the SDMs synch process (may to test/optimize for higher shutter speeds).

First of all, we need to know if the 1400 iterations in the code really do produce a delay of 0.1msec.
You would need an oscilloscope or some other equipment to measure that.
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Why the left cam shows Synch:0.0000
As I explained, the left camera flash fires immediately but at 1/16th power.

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and the right shows Synch:0.0040?
At higher speeds the delay is half the shutter speed.
For 1/250 sec, delay = 1/500 sec = 2msec = 20 SDM units of 0.1msec.
For 1/125 sec delay = 40 units.
For a shutter speed less than 1/125, we do not increase the delay even further, it is not necessary.
40 units is the maximum delay.

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What have conf.synch_delay_value and conf.synch_delay_coarse_value to do with it?
There is an option to set a user delay even when flash is not used.
You could set a delay of 5.0000 seconds on each camera to make a synchronised self-timer.
After a five second delay a synchronised pair of photos will be taken.
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Offline Microfunguy

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Re: Synch settings get lost (SDM 1.81)
« Reply #25 on: 03 / November / 2009, 14:08:16 »
Actually, there is an easier way of testing the flash delay parameters.
Set shutter-speed to 1/250 sec.
If you are 90% successful then that is good.
You could add a menu item that sets the value of the number of iterations for the 0.1 msec delay.
Default value would be 1400.
You can then play with altering that value.
You need to study how to add menu items.
That is useful anyway.

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Offline mr.burns

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Re: Synch settings get lost (SDM 1.81)
« Reply #26 on: 03 / November / 2009, 14:30:00 »
Hi,

first thanks for explanation, but I still have a general problem in understanding.  :blink:
The left cam fires immediately at 1/16 power of flash I understand.
The right cam gets a delay? Why? I thought cams should get synchronized, but right cam gets a delay compared to left cam? What for?

What is the difference of config setting enable_sync and enable_sync_delay?

Is synch to enable only if using flash? Or should I keep it enabled always?

What is the 'Add User and flash delays' option for?

If camera chooses 1/100 or 1/80 shutter speed, then synch shows sync:0.0000 (on right cam), but as you said, less than 1/125 it should still schow 0.0040? It shows only 0.0040 on 1/60 on my cam!

Thanks for further info!
« Last Edit: 03 / November / 2009, 14:33:01 by mr.burns »
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Offline Microfunguy

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Re: Synch settings get lost (SDM 1.81)
« Reply #27 on: 03 / November / 2009, 14:48:38 »
Quote from: mr.burns on 03 / November / 2009, 14:30:00
right cam gets a delay compared to left cam? What for?
As I explained, so that both cameras see the main full-power flash from the right camera.
If the right camera flash fired immediately, how do we know the left camera shutter has opened ?
It could open very slightly after the right shutter.

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What is the difference of config setting enable_sync

That ensures the cameras wait for switch release.
That is the method that gives excellent synch.

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enable_sync_delay?

That is required when using flash for the reasons discussed.

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Is synch to enable only if using flash? Or should I keep it enabled always?
For stereo photography with two cameras it should always be enabled.

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What is the 'Add User and flash delays' option for?
As I explained in previous post, you can add your own delay.
You need to add the same user delay to both cameras.
The above option then adds the additional delay needed for flash.
So, after a five second delay you can take a synchronised flash photo.

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If camera chooses 1/100 or 1/80 shutter speed, then synch shows sync:0.0000 (on right cam)

What Canon mode are you in and is 'F' displayed at top of screen when you half-press ?
If it is not, you are not in a valid mode for synch flash.
« Last Edit: 03 / November / 2009, 15:03:48 by Microfunguy »
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Offline mr.burns

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Re: Synch settings get lost (SDM 1.81)
« Reply #28 on: 04 / November / 2009, 02:31:55 »
Hi,

thanks, but still some questions:

Quote
right cam gets a delay compared to left cam? What for?
>As I explained, so that both cameras see the main full-power flash from the right camera.
>If the right camera flash fired immediately, how do we know the left camera shutter has opened ?
>It could open very slightly after the right shutter.
I measured using CRT monitor and found out that cams are synchronized at arround 1/7500 sek., does it not mean the flash should be seen by both cameras also without delay of right cam?

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enable_sync_delay?
>That is required when using flash for the reasons discussed.
Not really clear, if I enable/disable this option - what happens?
This option delays firing the flash? or What?

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What is the 'Add User and flash delays' option for?
>As I explained in previous post, you can add your own delay.
>You need to add the same user delay to both cameras.
>The above option then adds the additional delay needed for flash.
>So, after a five second delay you can take a synchronised flash photo.
'Add User and flash delays' this is just an boolean option - I can only enable or disable
What is the difference of 'Enable synch delay' and 'Add User and flash delays'?

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If camera chooses 1/100 or 1/80 shutter speed, then synch shows sync:0.0000 (on right cam)
>What Canon mode are you in and is 'F' displayed at top of screen when you half-press ?
>If it is not, you are not in a valid mode for synch flash.
I use manual mode, (but shutter speed and aperture I don't have any influence on)
and yes F is displayed if I half-press shutter button!

The Synch value (e.g. Synch:0.0040) what is shown on SDM display, what is this?
The delay of shooting a photo or the delay for the flash or what?

By the way, I have an oscilloscope! Can I help to measure the 1400 / 0.1 msec issue?

Thanks for further info!
« Last Edit: 04 / November / 2009, 09:14:34 by mr.burns »
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Offline Microfunguy

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Re: Synch settings get lost (SDM 1.81)
« Reply #29 on: 04 / November / 2009, 15:26:28 »
Quote from: mr.burns on 04 / November / 2009, 02:31:55
I measured using CRT monitor and found out that cams are synchronized at arround 1/7500 sek., does it not mean the flash should be seen by both cameras also without delay of right cam?
If you think the delay is not needed, remove it.
I explained above why it is used.

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This option delays firing the flash? or What?
I explained above it delays the firing of flash on right camera.

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What is the 'Add User and flash delays' option for?
I explained above.

Quote


The Synch value (e.g. Synch:0.0040) what is shown on SDM display, what is this?

I explained above.

By the way, I have an oscilloscope! Can I help to measure the 1400 / 0.1 msec issue?

[/quote]

You would need to trigger the 'scope on switch release and then measure the time until the blue led turned-off.
Do that with shutter-speed not overriden, the camera will choose 1/60 sec and synch delay will be 0.0040.
That is four msecs and should be about the same time to led off measured on your 'scope.
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