extra long exposures (split from: Hardcore modding on a A530, thanks to CHDK!

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Offline reyalp

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Hej,
Would it be possible to record the pic before the dark frame is taken, mostly for testing purposes ?
Yes, I implemented this (a540 only) a long time ago. http://chdk.setepontos.com/index.php/topic,1998.0.html
Don't forget what the H stands for.

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Offline mngc

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  • a590is fw 1.0.1b & sx110is fw 1.0b

Just curious, why 10 min exposure (with prolly very bad results) could be usefull ?

You are correct. 460 sec = 7.66Min exposure not too good, but not too bad. My goal the astro photgraphy with wide/normal/tele angle zoom, circle picture /point of Polaris star/, and software mixed lots of picture, and automated (?) meteor shower (meteors randomly with time) photograpy. I know various problem possibly, long test requied, to best result/time, picture piece, settings, and of course the real sky/. Now i in large city, this is worng for astro photography, night city light very bright. The CCD temperature important to noise ratio in long exposure. High temperaure = high noise, low temperature = low noise. But not all noise from temperature problem. With CHDK i see the temperature, great! For example CCD amplifier own noise... The final test requies dark sky and low temperature night, and of course equatorial mount with electronic drive. I know large CCD cameras are better than this equpment, peltier cooling more better, and infrared mod useful, for example Canon 300/350D. And special expensive CCD cameras too. But not have it, and too no have chdk, i think.     

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Offline mngc

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  • a590is fw 1.0.1b & sx110is fw 1.0b
@reyalp

Thanks the source, hard work, i see!

Good news, the dark frame set possibly in future. :) Master dark better, than one dark with lower exposure times too. CHDK has raw average, good function!

CHDK has a badpixel removal option, i can create badpixel bin with lua script. But i not know this badpixel information where from. The script takes picture, this is a dark or not dark picture, the scene (blue sky, or anyting, and settings important? Or this informations from canon firrmare ROM, etc.? Or this is equal the "light frame" in astrophotography corrections?

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Offline yvesson

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    • poll about some pics (not much serious) ^^
Hej,
Would it be possible to record the pic before the dark frame is taken, mostly for testing purposes ?
Yes, I implemented this (a540 only) a long time ago. http://chdk.setepontos.com/index.php/topic,1998.0.html


Hej,
Thanks for refreshing, I had missed that one. Luckily for me, we have the same cam. ^^


For another cameras users with extra long exposures (not a590is fw 1.0.1b) ok with 512 sec?

@3belas, your 512sec picture totally black or no?


I shot at the same setting and light condition and as a result, i got different pictures with difference lightness (exposure)..So i thought it was working.. No, my picture is not totally black..maybe i was mistaken (set it to different exposure, not 512 but 256..


my A590 is 101b
« Last Edit: 11 / June / 2009, 17:59:24 by 3belas »

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Offline reyalp

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CHDK has a badpixel removal option, i can create badpixel bin with lua script. But i not know this badpixel information where from. The script takes picture, this is a dark or not dark picture, the scene (blue sky, or anyting, and settings important? Or this informations from canon firrmare ROM, etc.? Or this is equal the "light frame" in astrophotography corrections?
The badpixel file is a list of the pixels the canon firmware sets to zero rather than blacklevel. These are interpolated over when dng is made. DNG spec requires this.

The reason a list is used is because scanning the entire raw buffer for zero pixels would be slow.

This isn't really correct, because the canon firmware does different things at different exposures.

If you use CHDK raw instead of DNG, it's ignored.

There is a second bad pixel system for user specified bad pixel lists: http://chdk.wikia.com/wiki/Badpixel_removal
Don't forget what the H stands for.

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Offline ewavr

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The reason a list is used is because scanning the entire raw buffer for zero pixels would be slow.
This isn't really correct, because the canon firmware does different things at different exposures.

But pixel from list is interpolated, if it is really bad (in patch_bad_pixels_b() function):

if (get_raw_pixel(ptr[0], ptr[1])==0) patch_bad_pixel(ptr[0], ptr[1]);

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Offline yvesson

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  • A540 SX10IS
    • poll about some pics (not much serious) ^^
Hej,
Just tested 1024s on my A540, and I got a 17min exposure pic, looking bad especially that I didn't let it substract a dark frame, would have been just too long. But now I wanna try again with the dark frame on, afterall, I'll host the pics somewhere and show the results here.


reyalp

The Long Exposure for A560 work perfectly, (64 to 2040s).
As soon as possible I'll up some work to my
http://ravelithium.deviantart.com/
Thank you a lot ^^

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Offline fudgey

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I guess this
http://chdk.setepontos.com/index.php/topic,3461.msg34615.html#msg34615
deserves a bump.

I see two downloads, no test reports for the a650.

 

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