SX510 - page 13 - CHDK Releases - CHDK Forum

SX510

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Offline ursamajor

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  • SX150IS, SX510HS
    • Per aspera ad astra...
Re: SX510
« Reply #120 on: 07 / January / 2015, 14:19:02 »
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For long exposures in astronomy purposes isn't reccomended to activate DFS (dark frame subtraction). Other methods to remove hot pixels are preffered. You made me curious. I'll take some long exposure pictures by activate DFS to see how the picture is processed. Without DFS, the details are astonishing, even at higher values of ISO and long exposure time (I experimented with 1600ISO and 4-5 minutes exposure). If DFS wouldn't remove the stars, by confusing them with hot pixels, it would be extraordinary.
SX510HS, SX150IS (retired) :D

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Offline reyalp

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Re: SX510
« Reply #121 on: 07 / January / 2015, 17:31:34 »
For long exposures in astronomy purposes isn't reccomended to activate DFS (dark frame subtraction)
Using dark frames is a very common technique in astrophotography.
Quote
If DFS wouldn't remove the stars, by confusing them with hot pixels, it would be extraordinary.
Canon dark frame works the essentially the same as dark frames are used in normal astrophotography: It takes an identical exposure with the shutter closed, and subtracts that from the real image. This takes care stuff like hot pixels and amp glow, and won't affect stars or details. There's no risk of hot pixels being confused with stars. The downside is that half you shooting time is taken up with the shutter closed.

It is conceivable that the variable we poke to control DFS has side effects on other parts of the Canon noise reduction process, but I haven't seen any evidence of this.

What I use for night photos is take a series of dark frames separately, average them (median is recommended, but in camera average is easy), and use that for shots with the same shutter and ISO. You do want the darks taken at approximately the same temperature, I have found that darks taken at 30-40c sensor temperature were noticeably too hot for shots taken at ~25c.
Don't forget what the H stands for.

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Offline reyalp

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Re: SX510
« Reply #122 on: 07 / January / 2015, 17:52:28 »
SX150 discussion moved to the porting thread: http://chdk.setepontos.com/index.php?topic=6953.msg119719#msg119719

Thanks andrew.stephens.754365 for following up and helping keep on things topic.
Don't forget what the H stands for.

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Offline ursamajor

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  • SX150IS, SX510HS
    • Per aspera ad astra...
Re: SX510
« Reply #123 on: 08 / January / 2015, 08:19:53 »
Canon dark frame works the essentially the same as dark frames are used in normal astrophotography: It takes an identical exposure with the shutter closed, and subtracts that from the real image.

Yes, in theory is the same, but practically on my Canon 550D I take lights then darks, flats, bias frames separatelly, then combine them using astrophoto software who has far better results than in camera processing, with DFS active.
SX510HS, SX150IS (retired) :D

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Offline philmoz

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Re: SX510
« Reply #124 on: 25 / January / 2015, 16:59:03 »
Maybe the zebra code could be modified to not write anything to
a) the cam's bitmap overlay
or
b) its internally malloc'd memory
but make boundary checks instead.
Or, does anyone have a better idea?
Using #define CAM_ZEBRA_NOBUF 1  camera has not crashed.
It is not perfect, but it is usable: https://trac.assembla.com/chdk/browser/trunk/modules/zebra.c#L150

The problem with the SX510 appears to be the definitions of vid_get_viewport_width() and vid_get_viewport_height().

These should return sizes in CHDK co-ordinates (360x240 or 480x240), not actual camera physical sizes - that's what the _proper() functions are for.

Compare the SX510 to the G1X to see the difference.

Because these functions are returning values much too large, the zebra code is drawing outside the memory buffer.

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)

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Offline srsa_4c

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Re: SX510
« Reply #125 on: 06 / February / 2015, 16:44:40 »
I found a bug in the viewport related routines (at least one address is wrong).

Looking for somebody with the camera who can do some testing.

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Offline reyalp

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Re: SX510
« Reply #126 on: 15 / February / 2015, 17:20:00 »
It looks like this camera has the same incorrect front dial code as sx160, sx170 and sx500: http://chdk.setepontos.com/index.php?topic=11164.220

I've checked the fix into the 1.4 trunk, autobuild 4010 and later. If anyone can confirm it still works correctly, that would be appreciated.
Don't forget what the H stands for.

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Offline asp

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Re: SX510
« Reply #127 on: 19 / February / 2015, 04:53:50 »
Hello everyone!
I'm new to this forum but am using chdk for over two years now on my PS A550 camera and did over 3 million shots shooting timelapse sequences.
i was using mostly intervalometer and sometimes hdr and stacking scripts and was very pleased with the functionality that chdk gave me over my cam.
The thing is i weared the sensor badly and now im into purchasing a new cam and got my eyes on the sx510hs.
I've read allmost anything regarding this model and am concerned about the "limited features" regarding this cam fw...don't want to buy a $200 cam that doesnt fulfill my needs (i own a D800 and some mid range lens - i would rather invest in battery grip or something else...)
so the question is:
Does this build support simple intervalometer without crashing and also i use focus distance overrides and ev bracketing for hdr...that's almost everything i need from my PS Cam so if it has isues i'll move along to another model...also got my eyes on SX230HS...that would be my #2 choice....
So i would appreciate your time to offer me some info about that....
THNX!

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Offline reyalp

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Re: SX510
« Reply #128 on: 19 / February / 2015, 22:21:31 »
also got my eyes on SX230HS...that would be my #2 choice....
So i would appreciate your time to offer me some info about that....
THNX!
Not sure what state the 510 is in.

The sx230 port has some unresolved issues, discussed in this thread http://chdk.setepontos.com/index.php?topic=12183.0 (I still need to find some time to work on that)
Don't forget what the H stands for.

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Offline asp

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Re: SX510
« Reply #129 on: 21 / February / 2015, 05:06:27 »
also got my eyes on SX230HS...that would be my #2 choice....
So i would appreciate your time to offer me some info about that....
THNX!
Not sure what state the 510 is in.

The sx230 port has some unresolved issues, discussed in this thread http://chdk.setepontos.com/index.php?topic=12183.0 (I still need to find some time to work on that)

thank you, not quite sure what to do, and i dont have much time either, i'm working on arboretum project and spring is coming fast and the flowering started already....will have to settle down for an older digic proc i suppose...

 

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