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SX100 IS

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Offline bether

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Re: SX100 IS
« Reply #170 on: 12 / July / 2008, 03:32:41 »
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Quote from: BB on 11 / July / 2008, 22:46:13
Actually, Hiker_Jon did some testing with a A720IS and found that when reviewing the RAW file, that ISO 800 and ISO 1600 produce identical RAW image files... That the camera was just using math to brighten the RAW file into JPEG:

in-camera EV+1

And some interesting information about in-camera JPEG processing.

Canon noise reduction

-Bill

RAW ISO 1600 and 800 is identical.
But I have qestion how works noise reduction in RAW mode because when I shoot NR - on and NR - off are produced RAW no differents. Maybe not working or what?
The examlple:
NR-on

NR-off

« Last Edit: 12 / July / 2008, 04:16:54 by bether »
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Offline BB

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Re: SX100 IS
« Reply #171 on: 12 / July / 2008, 05:02:48 »
That is because the NR (Noise Reduction) setting in the Canon P&S camera line is really "Dark Frame Subtraction" that is only done on shots that are ~2 seconds or longer (when set to "Auto" or normal camera function). Dark Frame Subtraction "NR" removes that fuzzy purple haze that is present in long time exposures and more prevalent when the sensor is warm or "hot".

If you look at the second link I posted, Hiker_Jon was reprocessing the RAW files with different ISO settings--which changed the Noise Reduction ("real" noise reduction  by averaging out noise) in the JPEG output (to very low levels of noise reduction at low ISO settings).

Read through the second link--it goes into great detail about "NR".

Canon noise reduction

-Bill

I guess I should clarify, I as understand, Dark Frame Subtraction will modify the "RAW" image file. And if "NR" is set to default, it only does the Dark Frame Subtraction for exposures longer than 1 second (and if there is purple haze is present--will not get rid of the the "color noise" or grainy look in any case)...

Noise Reduction is a post processing step that only affects the JPEG output. Here is where you will see the "smearing of colors" and plastic looking effect (at high ISO settings).
« Last Edit: 12 / July / 2008, 05:08:40 by BB »
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Offline ewavr

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Re: SX100 IS
« Reply #172 on: 12 / July / 2008, 05:47:27 »
Quote from: Newstech on 11 / July / 2008, 21:03:56
Yes.  I tried "wheel_right" and "wheel_left" but they did nothing.  Looks like to make them work, JogDial_CW and JogDial_CCW need to be defined.  If we had the wheel commands, then the various bracketing scripts could work.

Try http://ewavr.nm.ru/chdk/for_test/sx100-100c.zip (with src) - ported from G7 :)
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Offline Newstech

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Re: SX100 IS
« Reply #173 on: 12 / July / 2008, 09:23:56 »
Quote from: ewavr on 12 / July / 2008, 05:47:27

Try http://ewavr.nm.ru/chdk/for_test/sx100-100c.zip (with src) - ported from G7 :)
Oh, so close!! Thank you, but I'm afraid left and right are reversed.  "wheel_right" is producing a counterclockwise move, and vice versa.  Other than that, works like a charm.
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Offline RuLoXP

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Re: SX100 IS
« Reply #174 on: 12 / July / 2008, 10:28:20 »
Thanks everyone!

I've some doubts... When I take a picture with 1/3200 shutter speed  or higher, in EXIF appears 1/2500... Why?

Are there any way to preview RAW shoots on camera LCD?

Sorry for my english.
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Offline bether

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Re: SX100 IS
« Reply #175 on: 12 / July / 2008, 10:34:42 »
Quote from: BB on 12 / July / 2008, 05:02:48
That is because the NR (Noise Reduction) setting in the Canon P&S camera line is really "Dark Frame Subtraction" that is only done on shots that are ~2 seconds or longer (when set to "Auto" or normal camera function). Dark Frame Subtraction "NR" removes that fuzzy purple haze that is present in long time exposures and more prevalent when the sensor is warm or "hot".

If you look at the second link I posted, Hiker_Jon was reprocessing the RAW files with different ISO settings--which changed the Noise Reduction ("real" noise reduction  by averaging out noise) in the JPEG output (to very low levels of noise reduction at low ISO settings).

Read through the second link--it goes into great detail about "NR".

Canon noise reduction


hiker_jon wrote:
"So if you save raws and your picture taken at ISO 200 is too noisy you can use CHDK to develop the raw at ISO 800.  Conversely if you have an image at ISO 800 that has colors too smoothed by the noise reduction you can develop at ISO 80 to eliminate the noise reduction. "
It is working fine. NR as you like:)

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Offline RuLoXP

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Re: SX100 IS
« Reply #176 on: 12 / July / 2008, 11:02:26 »
More photos... I took photos ISO 16, is it real?
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Offline BB

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Re: SX100 IS
« Reply #177 on: 12 / July / 2008, 11:38:00 »
RuLoXP,

As of this time, when you override the camera's settings (shutter speed, ISO, etc.) past the camera's normal range with CHDK, the EXIF will not give you the real information--it just lists the maximum/minimum per the camera's specification.

At this point, nobody has figured out how to get the camera to write the proper EXIF data.

Also, when you push the ISO, Shutter Speed, etc. past the camera's ability (too fast, too slow, too high of ISO, too low of ISO), the camera will simply not make the change and only use its minimum / maximum capability... You set ISO to 15, camera may shoot ISO 50, and no lower...

Today, people have to just try the different settings and see where the image results stop changing (i.e., ISO 80, ISO 60, ISO 50, ISO 40, ISO 30, ISO 20...) until the see no difference with the last image...

-Bill
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Offline RuLoXP

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Re: SX100 IS
« Reply #178 on: 12 / July / 2008, 11:51:34 »
Mmm, I don't understand (my english...). So if in EXIF appears ISO-16, is it not real? and cannot I shoot 1/10000 pics? or I can but EXIF shows 1/2500...

Thanks and sorry for bothering you
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Offline BB

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Re: SX100 IS
« Reply #179 on: 12 / July / 2008, 12:39:39 »
RuLoXP,

I maybe wrong and CHDK does put the "commanded" EXIF numbers in the JPEG file.

But, in any case, you can set/command the camera to settings that it cannot do. CHDK will report the setting(s) that you programmed (and maybe EXIF will now report them)--but the camera cannot actually perform those settings (because of internal software and hardware limitations) and it will simply do the best it can, and no better.

Depending on the camera model (not all Canon P&S camera models have the same limits), you can shoot 1/10,000 sec. photograph, but the EXIF data will say 1/2,500 sec. You have to measure the shutter speed of your camera to see if it really took 1/2,500, 1/5,000 or 1/10,000 sec. picture.

Here are several examples of how the shutter speed was measured:

Samples: High-Speed Shutter & Flash-Sync - CHDK Wiki

Also note that sometimes there appear to be limits between zoom, shutter speed, and aperture settings inside the camera (hardware/software interactions). So, other settings (like zoom, aperture) may affect the maximum measured shutter speed.

-Bill
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