extra long exposures (split from: Hardcore modding on a A530, thanks to CHDK! - page 4 - General Discussion and Assistance - CHDK Forum

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

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Offline fudgey

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a570 100e works fine for me already.

With sources from reply #27 or #28?

#28 should be ok, I checked your fixes from my disassembly and they seemed correct.

For a570 100e diffs in #27 and #28 are the same now actually since I edited it after you posted the fixes. For 101a there's one difference (you forgot to list one more fix you made "BL      sub_ffebcfbc\n" -> "BL      sub_ffd0e5d4\n", about 10 lines from "loc_ffd20fa0:\n" forward.

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Offline ewavr

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What should I do to make this work in a S5 IS?

Please test - http://ewavr.nm.ru/chdk/for_test/

2 moderators: I propose to split this topic, because long exposures and modding on a A530 very different things.

edit: also for a550 - the same link.
« Last Edit: 10 / April / 2009, 18:26:46 by ewavr »

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bugmenot

quick question: what is the maximum exposure time now with this new feature?

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Offline ewavr

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Re: extra long exposures
« Reply #33 on: 10 / April / 2009, 18:25:50 »
quick question: what is the maximum exposure time now with this new feature?

We must make some experiments to answer this question.
IMO, it limited by battery life time and image quality.


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Offline barret

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how can i set those long exposure times? i cannot set it through 'extra photo operations' menu... max. is 64 sec.


thanks ewavr :)

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Set Shutterspeed enum type = factor
then set "override shutter speed" and "value factor"

update: it works!!! thank you ewavr!!! :D
on canon a550:
100 sec. works!
300 sec. works!
600 sec. works!
1200 sec. works!!!
although image quality (noise) is quite bad. how can we fight it?
« Last Edit: 11 / April / 2009, 10:41:17 by barret »

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Offline ewavr

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Re: extra long exposures
« Reply #35 on: 11 / April / 2009, 06:37:02 »
although image quality (noise) is quite bad. how can we fight it?

See http://chdk.setepontos.com/index.php/topic,3409.0.html  :D

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**Made an Amp-off circuit to control the CCD voltage during the exposure. This is to avoid the CCD glow at the corners of the image.
**Peltier cooling to reduce hot pixels and slightly increasing the sensitivity.

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Offline barret

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Quote
See http://chdk.setepontos.com/index.php/topic,3409.0.html  Big Grin
oh, yes, thank you, i've read that before :D interesting work, but rather extreme, don't you think? :D

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Offline ewavr

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Re: extra long exposures
« Reply #37 on: 11 / April / 2009, 06:44:01 »
Without hardware modding we can only:
 - use dark frame subtraction
 - use noise reduction software
 - use RAW sum (not average) of shorter exposures

 or buy DSLR with big sensor  ;)


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Offline fudgey

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I haven't done many test shots, but one 10 minute exposure with ISO80 F/11 (that aperture was to get rid of light, F2.6 got me severe overexposure in moonlight) was actually pretty good after Canon's dark frame removal. There was some noticeable noise in the top left corner where amp glow is the worst, but the photo is completely usable when scaled down a bit.

On the other hand, shots that long taken inside in poor light look very bad.

I was just wondering if there's a chance that an extended exposure time for the a590 might be available soon. Thanks to all the developers working on this, it really is great.

 

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