Building a mult-camera rig - page 19 - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum
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Building a mult-camera rig

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Offline waterwingz

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #180 on: 02 / September / 2014, 17:32:53 »
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Be aware that you can' t just set the shutter speed and assume the camera will get the ISO setting correct.  You need to set that too.   If the camera has an adjustable aperture and/or ND filter then setting that is also required to get the exposure correct.

Alternatively, you could implement a Tv priority mode in the camera side script.
« Last Edit: 02 / September / 2014, 17:44:27 by waterwingz »
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Offline reyalp

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #181 on: 02 / September / 2014, 22:48:47 »
To add to that, if you used the mc:cmdwait('call ...') method, you would apply the same settings to every camera. This might be what you want if you have good studio lighting. If it isn't, then you'd probably be better of using some kind of auto exposure, either the cameras or implemented in script as waterwingz suggested. Manually tweaking each camera doesn't seem like very good approach.
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Offline waterwingz

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #182 on: 02 / September / 2014, 23:06:55 »
Quote from: reyalp on 02 / September / 2014, 22:48:47
To add to that, if you used the mc:cmdwait('call ...') method, you would apply the same settings to every camera. This might be what you want if you have good studio lighting. If it isn't, then you'd probably be better of using some kind of auto exposure, either the cameras or implemented in script as waterwingz suggested. Manually tweaking each camera doesn't seem like very good approach.
What's worse for "bullet time" pictures?  Different shutter speeds or different ISO values?  Easy enough to lock either one in the camera side script and then fiddle the other parameter to get the exposure right.

I'm also thinking that what he probably really wants is an eV adjust setting common to all cameras?   Lock the shutter speed at something useful like 1/200,  pick the appropriate ISO setting for the current scene illlumination, and apply a common eV offset value sent from the computer side script.
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Offline andrew.stephens.754365

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #183 on: 03 / September / 2014, 15:18:26 »
Quote from: reyalp on 02 / September / 2014, 16:27:39
edit:
One important thing to remember if you are setting exposure parameters using lua functions is that in general, script overrides are only applied while the script that set them.

Not really concentrating on this closely - trying to learn Lua metatables etc so small clarification, please, for when I re-read someday:

=>One important thing to remember if you are setting exposure parameters using lua functions is that in general, script overrides are only applied while the script that set them is still running?
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Offline reyalp

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #184 on: 03 / September / 2014, 16:21:11 »
Quote from: andrew.stephens.754365 on 03 / September / 2014, 15:18:26
=>One important thing to remember if you are setting exposure parameters using lua functions is that in general, script overrides are only applied while the script that set them is still running?
Yes, typo. Sorry.  :(
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Offline waterwingz

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #185 on: 03 / September / 2014, 22:02:08 »
Updated  bcamRem.lua

Changes :
  • Selecting the REMOTE SYNC option now calls the usb_force_active() function to enable USB port sharing between PTP and remote sync.
  • Press the MENU key on the camera to exit the script.
  • Press the DISP key on the camera to toggle the OSD information on & off
  • Commands added to turn the OSD info on & off on all cameras from the host (see USAGE.TXT).
  • Added support for cmds.call() per http://chdk.setepontos.com/index.php?topic=11583.msg116338#msg116338
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Offline novsela

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #186 on: 04 / September / 2014, 02:51:10 »
thanks waterwings

will test it tonight

Attached here pics from last night of the rig with lighting
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Offline waterwingz

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #187 on: 04 / September / 2014, 10:07:30 »
I'm working on adding exposure control for the camera side script - probably Tv priority with ISO limits. You can do ISO priority with the standard Canon firmware already.
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Offline waterwingz

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #188 on: 07 / September / 2014, 13:48:52 »
Quote from: novsela on 02 / September / 2014, 16:43:04
When I run BcamRem.lua script on camera, is it still possible to use  >
Code: [Select]
!mc:cmdwait('call set_tv96_direct(1024)')
I updated the bcam.zip file to support this :  bcam_1-4.zip

To set the shutter speed for each camera and shoot, the command line is :

Code: [Select]
run  -e"exec bc=require('bcamHost') bc:command('call set_tv96_direct(1024)') bc:shoot()"Still pretty experimental - a Tv priority mode would be better I think.
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Offline novsela

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Re: Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue inpu
« Reply #189 on: 17 / September / 2014, 17:30:50 »
sorry for the delay, my wife gave birth this week.... so I am "Little" busy ;)

hope to update on Saturday
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