KAP & UAV Exposure Control Intervalometer Script

waterwingz

srsa_4c

waterwingz
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.)

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).

Wreck

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...

waterwingz

Wreck
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.

Wreck

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.

Wreck

Looks to be working pretty well now. Getting a few not-so-sharp images still, but could just be due to gimbal shake...

waterwingz

Wreck
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 ?

Wreck

waterwingz

Wreck
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.

waterwingz

Wreck
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 !

bisenberger

Hi waterwingz, would it be possible to add a function to turn off the camera when it completes shooting the total number of shots?

waterwingz

bisenberger
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?

waterwingz

Script updated to version 1.4. Changes include :

Addition of a minimum Tv setting to limit the slowest shutter speed that the script can use. In low lighting situations, this can lead to underexposed images that may need to be fixed in post processing but that's probably better than having correctly exposed blurred images.
Addition of an option to power the camera completely off when the specified number of shots has been taken.
Clean up to the text console to block less of the LCD image area.

Changelog and link on the wiki page : http://chdk.wikia.com/wiki/KAP_%26_UAV_Exposure_Control_Script

bisenberger

waterwingz

bisenberger
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?

Yes, that's the reason. Thanks for adding it to the script.

AndrewFerrara

First time on this forum. I just got a SX260 to use on a quadcopter. I want to take off without the lens extended and then start this script. How would some one go about doing that?

waterwingz

AndrewFerrara
First time on this forum. I just got a SX260 to use on a quadcopter. I want to take off without the lens extended and then start this script. How would some one go about doing that?

Easy - all you need to do is set the script's Start Delay and then start the script just prior to launch.

Do this :

Start your camera in "playback" mode rather than shooting mode (i.e. so the lens is not extended)
Activate CHDK and go to the Script menu.
Load the kap_ua.lua script.
Scroll down and set the "Start Delay Time (sec)" to your desired startup delay ( i.e. 60 seconds ?)
While still in <ALT> & in playback mode, start the script by pressing the shutter button fully.
Launch your UAV.

Sixty seconds later (depending on the delay you set) the camera will switch to shooting mode and the lens will extend.

Does that do it for you ?

WW

AndrewFerrara

Ok, thank you for the instructions. I just tested it and that will work well.

I see there is a parameter to turn off the backlight off. However, it doesn't appear that my backlight turns off what is this suppose to look like? Does the screen dim or turn off? It doesn't appear to be dimming.

waterwingz

AndrewFerrara
I see there is a parameter to turn off the backlight off. However, it doesn't appear that my backlight turns off what is this suppose to look like? Does the screen dim or turn off? It doesn't appear to be dimming.

If you have your shot rate set fairly high, on the order of one shot every 5 sec or less, then the backlight never gets a chance to turn off. Its a long standing limitation of the CHDK script set_backlight() command caused by the fact that the backlight turns on after every shot, requiring the script to pause briefly to turn it back off again.

You can test this for yourself by changing the shot interval to 60 seconds and observing the backlight when you run the script in that mode.

Fortunately, there is a new script command, set_lcd_display() that actually turns off both the backlight and the LCD itself. It has been available in the unstable testing version of CHDK for some time now. I have not used it in the kap_uav script as it was not available in the stable public version of CHDK. That changed two days ago thanks to philmoz - I just have not had a chance to update the script yet.

And as an added bonus, set_lcd_display() should save quite a bit more battery power than set_backlight()

waterwingz

Release 1.5 now available at the regular download link.

This version used set_lcd_display() rather than set_backlight() and requires a recent version of CHDK 1.2.0 or 1.3.0.

AndrewFerrara

I tired the script out the other day and it worked very well. However, I do need to make some adjustments to my setup to make it easier to use the camera (usb remote) and take better photos. A lot of them came out blurry. It was pretty windy though. Is there a way to correct this on the camera or do I just need a better anti-vibration setup? Right now the camera is directly mounted to the quadcopter in a case made from polymorph plastic (pictured below).

reyalp

From the exif, it looks like the focus mode is set to auto. You would probably be better off focusing at infinity. With the sort of camera, infinity should be fine for the kind of altitude you are shooting from.

Since your camera has MF, you should be able to just set it to MF mode and adjust the focus before flight. There might be a way to do this from script, but it varies a lot by camera so a manual test is likely to be more reliable. It looks like the camera is in full auto mode, you may need to switch the camera to P mode to turn off autofocus.

I'm not sure if all of your problem focus, there could well be some motion blur from vibration in there too, but

exiftool -a -u -g1 -h IMG_0181.JPG  > IMG_0181.HTML

reports

Focus Distance Upper	0.78 m

which I think indicates that it was trying to focus quite close. If I set my D10 to infinity in MF mode, I get

Focus Distance Upper	15.69 m
Focus Distance Lower	0 m

The exposure was 1/1000th which should be pretty good for keeping motion blur down with wide angle shots like that.

waterwingz

The script supports various methods of setting focus at infinity, selectable by a user defined @param value. You might have to tweak the code for your particular camera though.

Details are discussed in the Wiki page documentation for the script (linked in the first post of this thread).

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