Long-Exposure Continuous Shooting (for star trails or other uses)

reyalp

waterwingz
Seems like the half_shoot is where the camera decides on the exposure and focus settings, so you'd want to insert the overrides after that?

The CHDK override hook gets called during half shoot, so script needs to set beforehand. The script call just sets a variable the override hook will read later.

If you want to manipulate things inside half_shoot, you can do it by setting propcases directly, though I'm not sure how reliable or sensitive to timing this method is.

waterwingz

reyalp
The CHDK override hook gets called during half shoot, so script needs to set beforehand. The script call just sets a variable the override hook will read later.

So the correct way to think about this is that you set overrides before the half-shoot determines exposure and they will replace what half-shoot came up with.

Where does set_aflock() fit into this process ?

I'm thinking a wiki page is in order here ... I usually get it to work right with each new script but I feel like I always end up "re-inventing the wheel".

reyalp

waterwingz
So the correct way to think about this is that you set overrides before the half-shoot determines exposure and they will replace what half-shoot came up with.

Right. Which is actually undesirable if you want to base your exposure on the measured Bv, since it only updates in half shoot. We've discussed this somewhere before.... https://chdk.setepontos.com/d/9110/1

Hmm, I thought you were involved too, maybe a different thread.

Where does set_aflock() fit into this process ?

Beats me, haven't played with that one much. But set_aflock() calls the Canon function directly rather than setting a flag for the override hook.

waterwingz

reyalp
Right. Which is actually undesirable if you want to base your exposure on the measured Bv, since it only updates in half shoot.

That's why some of my script do a half-press and release just to get the current Bv prior to actually doing a shoot().

Where does set_aflock() fit into this process ?

Beats me, haven't played with that one much. But set_aflock() calls the Canon function directly rather than setting a flag for the override hook.

Seems like philmoz tried to shed some light on the correct placement a couple of months ago. I'll go back and look for it.

Update : in case I end up back here, the post was : https://chdk.setepontos.com/d/9533/11

Intheswamp

Just so you don't think I'm a hit-and-run user I want to let ya'll know that I'm still here...ya'll pretty well lost me on page two but I'm still here. 😀

Ed

waterwingz

Intheswamp
Just so you don't think I'm a hit-and-run user I want to let ya'll know that I'm still here...ya'll pretty well lost me on page two but I'm still here. 😀

Thanks. Here's the latest version - seems to work more stably than the rest although the first time it runs it still does not always use long exposures.

Give it a try and see what it does for you?

lecshoot.lua

1.07KB

Intheswamp

I will check it out this evening. I've got the A1200 perched in a downtown window taking a time lapse series. I set up a weather station website a couple of months ago and have started uploading a time lapse of weather every few days...cloud movement is very interesting. I'm still figuring out the best settings for the movies. If your curious about them the videos are at http://www.beeweather.com/wxtlapse001.php . The name of the website incorporates another hobby of mine...honey bees. I've still got to get a greater presence of the bees on the website, though. CHDK has been a treat for me! 😀

Ed

waterwingz

Intheswamp
If your curious about them the videos are at http://www.beeweather.com/wxtlapse001.php .

Nice - you certainly get some interesting weather this time of year down there in L.A.

Roll tide.

Intheswamp

Thanks Waterwingz. Yelp, we are having a very odd summer down here. It should be busting 100F and DRY right now...we've had more rain this summer than I recall in recent times and the temperature has only gotten up to around 95-96F....it's really been a nice, (mostly) comfortable summer...if you can ignore the humidity! 😁

For anybody that has ever driven highway 331 to the beaches down at Destin/Ft.Walton then you very well may have driven down the street shown in some of the timelapses...it is downtown Luverne, Alabama.

Yo!!!....ROLL TIDE!!!!!!!!! Dang that felt good to this redneck! 😉

Intheswamp

Well, I finally made it back an lecshoot.lua seems to be working good. I've still gotta memorize all the key presses on the A1200 so I can turn the lcd off and then start lecshoot.lua. It's coming together and a far cry better than before I found CHDK!!!! 😁

THANKS!!
Ed

waterwingz

Intheswamp
I've still gotta memorize all the key presses on the A1200 so I can turn the lcd off and then start lecshoot.lua.

This will disable the display on your A1200 automagically and also disable dark frame subtraction for you :

--[[
@title Long-Exposure Continuous Shooting
@param   a Exposure Time (Seconds)
@default a 10
@range   a 1 60
@param   b Number of Shots
@default b 10
@range   b 0 9999
@param   d Display On
@range   d 0 1
@default d 1
@param   f Dark Frame Disabled
@range   f 0 1
@default f 0
]]

function set_display_key(m)  -- click display key to get to desire LCD display mode 0=off, 1=on
    if (m==0) then m=2 else m=0 end
    local count=5
    local clicks=0
    sleep(200)
    repeat
        disp = get_prop(props.DISPLAY_MODE)
        if ( disp ~= m ) then
            click("display")
            clicks=clicks+1
            sleep(500)
        end
        count=count-1
    until (( disp==m ) or (count==0))
    if (clicks>0 and count==0) then
       print("unable to change display")
    end
end

--This is an array of TV96 values for exposure times 1-60 seconds.
--It is indexed by the exposure time in seconds.
expVAL = {0, -96, -152, -192, -223, -248, -270, -288, -304, -319, -332, -344, -355, -366, -375, -384, -392, -400, -408, 415, -422, -428, -434, -440, -446, -451, -456, -462, -466, -471, -476, -480, -484, -488, -492, -496, -500, -504, -507, -511, -514, -518, -521, -524, -527, -530, -533, -536, -539, -542, -545, -547, -550, -552, -555, -558, -560, -562, -565, -567}

--This is the main part of the script - CAMERA MUST BE IN CONTINUOUS DRIVE MODE

props=require("propcase")
set_raw_nr(f) -- disable Canon's dark frame reduction if selected
set_display_key(d)
if(b>0)then
  b=b+get_exp_count()
end
if(b>9999) then b=b-9999 end -- starts from 1 again
print("exp:",expVAL[a])
sleep(2000)
set_iso_real( 80 )
set_tv96_direct( expVAL[a] )
press("shoot_half")
repeat sleep(50) until get_shooting() == true
press("shoot_full")
repeat sleep(10) until get_exp_count()==b
release("shoot_full")
release("shoot_half")
set_display_key(1)
set_raw_nr(0) -- enable Canon's dark frame reduction

lecshoot.lua

1.9KB

Intheswamp

Thanks, waterwingz! Last night was the first semi-clear night we've had in a long time...we've had unseasonably wet and cool weather this summer down here in south Alabama...odd, but nice. But, we've had a lot of fog, overcast skies from it.

I installed your latest code modification and ran it last night for roughly three of hours. The video isn't anything fancy but it's got me excited about the clear nights we will probably get this winter!

At 13 seconds into the video there is an UFO :😀 in the lower left hand corner of the screen. Two lights appear in one frame. Maybe a meteor coming more directly at us rather than streaking past us or something...?

Camera settings:
Resolution: L - 4000x3000
ISO: 100 (picture shows 125)
Shutter Exposure: 16 seconds (picture shows 15 seconds)
Aperture: f2.8 (from picture)
Mode: Program
Selected: Continuous Shooting

Video: http://www.beeweather.com/wximages/Stars01.avi
Jpeg: http://www.beeweather.com/wximages/Stars01-2lights.JPG

The script seems to be working the way intended...thanks for the tweaking!! 😉

A question I have is the camera noise...I guess that is just something I'll have to live with? I'm don't how to use them, but is it possible to use darkframes with a timelapse video like this to take out the noise or is that only only for star-trail still pictures?

Thanks!
Ed

ETA: Camera was pointed to the north.

waterwingz

Intheswamp
A question I have is the camera noise...I guess that is just something I'll have to live with? I'm don't how to use them, but is it possible to use darkframes with a timelapse video like this to take out the noise or is that only only for star-trail still pictures?

To tell the truth, I've been wondering why you were not just using this script :

http://chdk.wikia.com/wiki/Meteor_Intervalometer_with_Dark_Frame_Management

It takes very slightly longer between shots as its not in continuous mode but it does have one significant advantage - it periodially takes dark frames for you.

Something like this will let you post process the dark frames against each image prior to making your video :

http://www.mediachance.com/digicam/blackframe.htm
http://www.startrails.de/html/software.html

There are more options here :

http://chdk.wikia.com/wiki/Software#Stacking_.26_HDR
http://chdk.wikia.com/wiki/Stacking_Software

Intheswamp

Thanks, I'll take a look at those links. My primary intent with the lecshoot.lua script is to shoot lightning storms at night...shooting stars and meteor showers is an afterthought. Multi-purpose too. 😀

I think that answers a question that I had about whether I could use dark frames with the timelapse. My A1200 definitely picked up some noise last night.

<sigh> I tend to go check things while I'm posting... I remember now that I had tried to use meteor.lua earlier before I found lecshot.lua. I loaded up meteor.lua a couple of minutes ago and I get the error "your CHDK does not support native calls." I think there's a German CHDK version that includes the native calls and then I have to add something else to convert German to English?

Ed

waterwingz

Intheswamp
I tend to go check things while I'm posting... I remember now that I had tried to use meteor.lua earlier before I found lecshot.lua. I loaded up meteor.lua a couple of minutes ago and I get the error "your CHDK does not support native calls." I think there's a German CHDK version that includes the native calls and then I have to add something else to convert German to English?

The current stable version of CHDK (released earlier this week) now has an option in the miscellaneous menu that will allow you to enable "native calls". You probably want to update your CHDK if you have not already done so.

Update : You could also stick with the lecshoot.lua script and periodically create a dark frame manually by placing a lens cap or other black object so that it completely covers the lens for one shot.

Intheswamp

Ok, I've updated to the latest CHDK version and the meteor.lua script runs. 😀 Now my finite brain has got to figure out how to use dark frames. It sounds like dark frames need to have RAW files to work for best results, though it seems I read that dark frames will work with jpegs but not as well. Is this correct? I'm just thinking of the extra time it takes to write the RAW files and also the size of them. I would like to work with jpegs first, then move on to RAW files. Is it possible to use jpegs and dark frames?

Am I correct in thinking that if CHDK's parameters are set at 'default' then the default meteor.lua script will set the RAW configurations up correctly? Will all that I need to do be change the four options at the bottom of the script menu (if I wish to)...Number of shots, Raw On/Off, Shots per Dark Frame, and exposure in seconds?

I'm hoping that I can get some clear nights before the Perseids arrive so that I can get maybe an hour of exposures so I can tinker with some of the dark frame software... but for the next several days we have chances for rain during the day which means a good chance of humid, foggy nights. I'm hoping for at least clear nights during the actual event...we'll see.

Thanks for the files and file links and for suggesting that I upgrade CHDK!! I've got *lots* to learn!!!
Ed

waterwingz

Intheswamp
Ok, I've updated to the latest CHDK version and the meteor.lua script runs. 😀 Now my finite brain has got to figure out how to use dark frames. It sounds like dark frames need to have RAW files to work for best results, though it seems I read that dark frames will work with jpegs but not as well. Is this correct?

I believe that is correct. The RAW images and the RAW dark frame are a pixel-by-pixel match with the sensor so correction can happen on a per pixel basis. JPG's are compressed so getting exact pixel correction might be tough.

But somebody else with more experience in post processing might want to chime in here? blackhole ?

I'm just thinking of the extra time it takes to write the RAW files and also the size of them.

Get a large & fast SD card ( 16G class 10 ) and the difference will be minimal.

Am I correct in thinking that if CHDK's parameters are set at 'default' then the default meteor.lua script will set the RAW configurations up correctly?

Yes - but you need to check that RAW is setup to save as DNG files. Its the same information but there is a header attached that most photoprocessing software can work with.

blackhole

Ok, I've updated to the latest CHDK version and the meteor.lua script runs. Now my finite brain has got to figure out how to use dark frames. It sounds like dark frames need to have RAW files to work for best results, though it seems I read that dark frames will work with jpegs but not as well. Is this correct?

I believe that is correct. The RAW images and the RAW dark frame are a pixel-by-pixel match with the sensor so correction can happen on a per pixel basis. JPG's are compressed so getting exact pixel correction might be tough.

You're right, but for startrails jpeg will be OK.
With the settings I would not go over TV15 and ISO 125

Intheswamp

Thanks for the feedback, ya'll are teaching this ol' country boy somethings. 😁

waterwingz, I've got the SDHC card covered...I've got a 16gb class 10 card that I've been using. I'll check and be sure that .DNG is selected.

blackhole, thanks for the input. What I'm trying to shoot is a moving star field...can I take it that jpeg will be ok for this, also?

A couple of questions/observations:

I noticed in the CHDK configuration menu that DFS defaulted to 'Auto'...should I set this to 'Off" or will meteor.lua disregard the setting and use it's own configured dark frame exposure rate (default of 1:50/dark:light)?

In the CHDK settings DNG Version defaults to v1.3. The manual states that maximum compatibility is found while using v1.1. Since I'm not sure yet which (free) software I will be using would it be a good idea to change the setting to v1.1?

Temperature of CCD? What would be rough low-noise, high-noise, and danger-level values for this?

I didn't really realize just how indepth this software goes!!!

Thanks for your patience and help!!
Ed

ETA: One more question and I promise to try and be 😖 for a while. 😀 Is it better for the RAW images be placed in the directories with the jpegs or in the Canon directory?

waterwingz

Intheswamp
I noticed in the CHDK configuration menu that DFS defaulted to 'Auto'...should I set this to 'Off" or will meteor.lua disregard the setting and use it's own configured dark frame exposure rate (default of 1:50/dark:light)?

The script will override the menu setting and reset it when it is done.

In the CHDK settings DNG Version defaults to v1.3. The manual states that maximum compatibility is found while using v1.1. Since I'm not sure yet which (free) software I will be using would it be a good idea to change the setting to v1.1?

Yes

Temperature of CCD? What would be rough low-noise, high-noise, and danger-level values for this?

I don't think anyone really knows - and there is not a lot you can do about it anyway.

One more question and I promise to try and be 😖 for a while. 😀 Is it better for the RAW images be placed in the directories with the jpegs or in the Canon directory?

Doesn't matter to CHDK or the camera. Just a question of where you want to find them when you put your card in your PC card reader.

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