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KAP & UAV Exposure Control Intervalometer Script

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Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #60 on: 08 / December / 2013, 10:56:40 »
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The script does not correctly handle the situation where the camera wants to insert the ND filter and reports using a smaller f-stop setting as a result.   It assumes the reported Av value is the actual aperture f-stop setting and does its exposure calculations based on that.  When the actual shot occurs, it ends up using calculations based on the ND filter being inserted even though it does not insert that filter.
I thought PROPCASE_AV should show the chosen Av value (it seemed to when I recorded the possible Av values).
I thought so too.  But looking at the logs posted above,  the Av values I highlighted in red are straight from a get_av96() call and as I commented,  for the SD980 they can only change like that if the zoom shifts or the ND filter engages.   The OP says he did not move the zoom,  so that leads me to the conclusion that PROPCASE_AV is changed when the camera plans to insert the ND filter.  (i.e. the reported APEX96 value is the  effective aperature value and not the ratio of the lens' focal length to the diameter of the entrance pupil.)

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The fix for cameras without an adjustable aperture is to use  get_prop(props.MIN_AV) to determine the actual Av96 value of the aperture rather than the get_av96() function.
This is probably correct for DOF calculations, but is it really good basis for determining exposure?
On a camera without an adjustable aperature this works correctly (assuming you control the ND filter in the script as well) and is a tricky way to detect if the camera planned to use the ND filter (thanks to reyalp for that one).   

Meanwhile, at least for now, the script logic for cameras with adjustable aperature assumes the camera does not try to use the ND filter automatically (based on my testing and an IRC conversation with reyalp).

« Last Edit: 08 / December / 2013, 11:03:42 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline Wreck

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Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #61 on: 08 / December / 2013, 14:26:57 »
I've just tried the v1.3 script, with Avmode set to ndfltr and I don't seem to be getting overexposure (just shooting a bright scene outside the window).

2013Dec09 07:15:03 KAP 1.2 started - press MENU to exit
2013Dec09 07:15:03 CHDK 1.2.0-3155-0 ixus110_sd960 101d Oct 13 2013
2013Dec09 07:15:03  Tv:1/1250 maxTV:1/2000 exp comp:0.0
2013Dec09 07:15:03  Av:4.0 minAv:2.8 maxAv:8.0
2013Dec09 07:15:04  ISOmin:100 ISO1:400 ISO2:800
2013Dec09 07:15:04  AvM:2 int:2 Shts:0 Dly:0 B/L:0 USB:false
2013Dec09 07:15:17 1) IMG_1214.JPG
2013Dec09 07:15:18  meter : Tv:1/500 Av:2.8 Sv:80 774:774
2013Dec09 07:15:18  actual: Tv:1/1250 Av:- Sv:200
2013Dec09 07:15:18          AvMin:2.8 NDF:NDout foc:infinity
2013Dec09 07:15:24 2) IMG_1215.JPG
2013Dec09 07:15:24  meter : Tv:1/200 Av:5.6 Sv:80 845:845
2013Dec09 07:15:25  actual: Tv:1/1250 Av:- Sv:120
2013Dec09 07:15:25          AvMin:2.8 NDF:NDout foc:infinity
2013Dec09 07:15:32 3) IMG_1216.JPG
2013Dec09 07:15:32  meter : Tv:1/200 Av:2.8 Sv:n/a 719:719
2013Dec09 07:15:32  actual: Tv:1/1250 Av:- Sv:320
2013Dec09 07:15:32          AvMin:2.8 NDF:NDout foc:infinity

Exif values:
IMG_1214.JPG - 1/320, f2.8, iso 50
IMG_1215.JPG - 1/500, f5.6, iso 50
IMG_1216.JPG - 1/1250 f2.8, iso 320
IMG_1217.JPG - 1/1250 f2.8, iso 250

A subsequent test of 6 shots gives exif showing 1/1250. I'll strap it to the copter and give it a proper go this afternoon if I can sort out my GPS issues...

Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #62 on: 08 / December / 2013, 16:54:01 »
A subsequent test of 6 shots gives exif showing 1/1250.
Sound a bit like the bug srsa_4c patched yesterday.  If you download the latest build from the autobuild this might just go away.
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline Wreck

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Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #63 on: 08 / December / 2013, 19:34:16 »
Have just installed the latest build, and with the 1.3 script it seems to be behaving from my limited backyard test. Will have to see how it goes in the air and report back.

Thanks for your help.


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Offline Wreck

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Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #64 on: 09 / December / 2013, 20:22:49 »
Looks to be working pretty well now. Getting a few not-so-sharp images still, but could just be due to gimbal shake...


Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #65 on: 09 / December / 2013, 20:26:38 »
Looks to be working pretty well now. Getting a few not-so-sharp images still, but could just be due to gimbal shake...
Good to hear - thanks for reporting back! 

What Tv value is reported in the exif & the script log for those images ?
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline Wreck

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Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #66 on: 09 / December / 2013, 20:32:56 »
Looks to be working pretty well now. Getting a few not-so-sharp images still, but could just be due to gimbal shake...
Good to hear - thanks for reporting back! 

What Tv value is reported in the exif & the script log for those images ?

Here's a selection.

2013Dec10 11:05:32 30) IMG_1390.JPG
2013Dec10 11:05:32  meter : Tv:1/400 Av:2.8 Sv:80 753:753
2013Dec10 11:05:32  actual: Tv:1/1600 Av:- Sv:320
2013Dec10 11:05:32          AvMin:2.8 NDF:NDout foc:infinity
2013Dec10 11:05:38 31) IMG_1391.JPG
2013Dec10 11:05:38  meter : Tv:1/320 Av:2.8 Sv:80 733:733
2013Dec10 11:05:39  actual: Tv:1/1600 Av:- Sv:320
2013Dec10 11:05:39          AvMin:2.8 NDF:NDout foc:infinity
2013Dec10 11:05:46 32) IMG_1392.JPG
2013Dec10 11:05:46  meter : Tv:1/400 Av:2.8 Sv:80 739:739
2013Dec10 11:05:46  actual: Tv:1/1600 Av:- Sv:320
2013Dec10 11:05:46          AvMin:2.8 NDF:NDout foc:infinity
2013Dec10 11:05:53 33) IMG_1393.JPG
2013Dec10 11:05:53  meter : Tv:1/640 Av:2.8 Sv:80 809:809
2013Dec10 11:05:53  actual: Tv:1/1600 Av:- Sv:200
2013Dec10 11:05:53          AvMin:2.8 NDF:NDout foc:infinity
2013Dec10 11:05:59 34) IMG_1394.JPG
2013Dec10 11:06:00  meter : Tv:1/640 Av:2.8 Sv:80 810:810
2013Dec10 11:06:00  actual: Tv:1/1600 Av:- Sv:200
2013Dec10 11:06:00          AvMin:2.8 NDF:NDout foc:infinity

Exif shows all were shot at 1/1600, f2.8, and the ISOs all match up.

Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #67 on: 09 / December / 2013, 20:43:53 »
Exif shows all were shot at 1/1600, f2.8, and the ISOs all match up.
Gotta like that!   Thanks to srsa_4c for making the fix to the SD980 !
Ported :   A1200    SD940   G10    Powershot N    G16


Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #68 on: 10 / December / 2013, 16:21:15 »
Hi waterwingz, would it be possible to add a function to turn off the camera when it completes shooting the total number of shots?

Re: KAP & UAV Exposure Control Intervalometer Script
« Reply #69 on: 10 / December / 2013, 16:50:59 »
Hi waterwingz, would it be possible to add a function to turn off the camera when it completes shooting the total number of shots?
Doesn't sound like a big problem to add.   At one point I had the code simply switch to playback when shooting was done so that the lens could retract prior to landing.   I assume you are asking for the same reason?
Ported :   A1200    SD940   G10    Powershot N    G16

 

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