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Motion detector question

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Motion detector question
« on: 01 / July / 2011, 21:13:58 »
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Hi,

Fellows, have mercy....

I want to use my SX20!S to take flash pictures of bats feeding at my hummingbird feeders (not kidding!)
I am going to outline what I've done so someone may be able to tell me where I went wrong.

I have have downloaded and installed the latest CHDK for my camera and the Motion detector script recommended : MDFB-080914-VideoButtonModels.bas.

First I've set the shutter in CHDK menu to 1/50,000  value 1 and aperture to f16.
Next I go to the scripts menu and load the appropriate MDFB (MDFB-080914) where I set Script shoot delay=0;
Autostart =off;Threshold=1;Shootfast=0;Enable Flash is checked. All other values are default.
 Next, I hit my video button the lens goes out and I set up Manual, Manual focus, and Flash to fire.
Next I hit the printer button to start MDFB, hit the shutter button to run the script and then hit the
printer button.

The grid comes on I drop something in front on the lens ,it fires  and then shuts down. The camera turns itself off.
Fresh batteries. It shuts down repeatedly.

What is the proper procedure, and what am I doing wrong?

Lebowski



Lebowski
« Last Edit: 01 / July / 2011, 23:12:13 by Lebowski »

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Offline reyalp

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Re: Motion detector question
« Reply #1 on: 02 / July / 2011, 00:03:47 »
The camera is crashing. Not immediately obvious why, probably a bug. It's possible a different combination of settings will avoid it.

Quote
First I've set the shutter in CHDK menu to 1/50,000  value 1 and aperture to f16
This seems like the opposite of what you want. With the flash, it doesn't really matter if the shutter is open for a relatively long time, and the small aperture isn't likely to be good at night.
Don't forget what the H stands for.

Re: Motion detector question
« Reply #2 on: 02 / July / 2011, 00:29:48 »
Thanks for the reply, I'll try different settings.

As for the f16 setting. I am using my camera flash to trigger two studio flash heads because from tests I did using a hacked hard wired motion detector, I need the depth of field the more powerful flash units give me.
You are right about the speed but I was following the settings of some of the water droplet photos I've seen here.

Lebowski

Re: Motion detector question
« Reply #3 on: 02 / July / 2011, 06:29:18 »

As for the f16 setting... I need the depth of field


You realise that is equivalent to f90 on a 35mm camera !!!! ?

Definition will be terrible.
I suggest you do a test and post the results to prove the point.

As for a shutter speed of 1/50,000  .. that is imaginary .. you will not achieve such a speed with CHDK.
The speed will be determined by your flash units.


Re: Motion detector question
« Reply #4 on: 02 / July / 2011, 12:01:40 »
I based my exposure data on tests I did with my Sony DSC-R1. With this model the minimum aperture you can set is Fl6 and the maximum speed setting is 1/2000.
I have included two examples in this post for you to review and perhaps give me some guidance.
I was unhappy with these results primarily because the sensor I rigged to set off the camera has a too slow response time
to get consistently good results. It also lacks any type of sensitivity control and is dependent on trial and error placement.  It uses an infrared sensor to trigger a radio response which is good for me because I am photographing them in pitch darkness.

 I "discovered" CHDK two days ago and could barely contain myself with the possibilities of this software. However, now that I understand the software (MDFB) a bit better it will only work for me if there is a change it light which registers on the CCD. Is this correct?   If so, this does not bode well for shooting in total darkness.


Here are my example files.

Bat1- Photo with just the onboard flash-F7.1@1/2000
Bat2. Photo with Onboard flash triggering Broncolor Flashman with 3 heads-F16@1/2000

I will post other examples on another post of the same setup with hummingbirds.


Re: Motion detector question/further examples
« Reply #5 on: 02 / July / 2011, 12:04:09 »
Hummingbirds at F16@1/2000

See above post.

Re: Motion detector question/Setup
« Reply #6 on: 02 / July / 2011, 12:07:26 »
Here is my setup for the above photos

Re: Motion detector question
« Reply #7 on: 02 / July / 2011, 12:10:22 »
However, now that I understand the software (MDFB) a bit better it will only work for me if there is a change it light which registers on the CCD. Is this correct?   If so, this does not bode well for shooting in total darkness.
Well, changes in light level is pretty much all CHDK has to work with.  What would you propose as an alternative for total darkness ?  Ultrasonic sensor ?  Radar ?  Audio noise ?  Sonar ? Thermal IR imagining ?  Tripwire ? Pressure mat ?  Pretty much all things that would require additional hardware not built into your camera.  Although building such an external device and attaching to your camera as a USB-remote might be an interesting project.

Ported :   A1200    SD940   G10    Powershot N    G16


Re: Motion detector question
« Reply #8 on: 02 / July / 2011, 12:29:02 »
 I think CHDK is incredible. I just did not know how it worked initially.

I am using an external device now. That infrared sensor. The hacked Driveway Alert device.

 I could hook it up so motion fires the flash rather than the camera. It would be like shooting lightning. The flash would be detected by the MDFB motion detector software in the camera. Is the response time of MDFB software pretty quick? Still I would be left depending on the infrared sensor for initial detection which I was hoping to avoid.

Re: Motion detector question
« Reply #9 on: 02 / July / 2011, 13:31:58 »
Hummingbirds at F16@1/2000

See above post.

The DSC-R1 has an APS-sized sensor, 21.5 x 14.4mm.

The Sx20IS has a 1/2.3" sensor just 6.17 x 4.55mm.

That drastically changes the effective f#.

Don't take my word for it, post an SX20IS image taken at f16 and one taken at widest aperture.

I sent someone details of how he could use SDM (my adaptation of an early CHDK) for the sort of shots you describe using some simple external electronics.

It even works in full daylight.

I never received a reply.

David

 

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