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Allbest - SD1000 ISO and shutter speeds incorrect?

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Offline Coutts

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Allbest - SD1000 ISO and shutter speeds incorrect?
« on: 19 / February / 2008, 13:36:29 »
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so i've been testing the latest allbest build out on my SD1000, i set the shutter speed override to 1 and the factor to 100. The result was an amazing night shot (taken at 1:30am):



the exif data claimed it to be a 70 second exposure. so i thought i'd try a longer one. i set the shutter speed override to 2, with a factor of 100 (should produce a 200 second exposure right?). the resulting image's exif data claimed a 136 second exposure, yet it looked exactly like the previous 70 second exposure. whats going on here?

I set the iso override to 54 with a factor of 100, and when i hold the shutter half way it focuses and says its using ISO 8000, i take a picture and its very grainy. I then take a picture with the override set at like 20 or so (cant remember) and it says the ISO is set to 1600. i compared the ISO 1600 picture to a picture i took by setting the iso to 1600 normally (camera can do 1600 on its own) and it is significantly darker than the overridden one at the same shutter speed, it is also hardly worse than the ISO 8000 one (the iso 8000 one wasnt nearly as bright as it should have been) which leads me to believe though it claims to use ISO 8000, its actually using a significantly lower one, and thought it claims shutter speeds of 136 seconds, its only doing a 70 second exposure.

i did another test setting the shutter speed override to 70 seconds and used a timer to time the exposure, it came out to be 64 seconds give or take a second or 2 for reaction times sake. any ideas people? Why is this so inaccurate? am i just doing it wrong?


Also when using exposure bracketing in continuous mode, after combining the images in photomatix the result is an extremely grainy picture, yet they look clear when i took the pictures, any ideas on this one? it never did this before i had chdk on the camera (back when i used the built in exposure compensation control).

What do you guys think is going on here?
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Offline Barney Fife

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #1 on: 19 / February / 2008, 22:51:14 »
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« Last Edit: 22 / April / 2008, 12:26:27 by Barney Fife »
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Offline Coutts

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #2 on: 20 / February / 2008, 13:04:51 »
yup looks like the limit for my camera is 65 seconds. i set the override to 100 and used a timer and found it captured for 65 seconds, same for the 200 setting so im guessing that is the limit.

the thing im unsure about on the ISO is there is no way to cross reference it (like using a realtime timer with the shutter speed), i've had settings go as low as 15 and the highest i've had is 8000, yet it hardly looks better than 1600.

as for the exposure bracketing, is there a limit to how high it can go? the longest i've tried is 13 exposures at 1 step intervals, = -6 to +6 exposure compensation. any more info on this?

also after reading how the shutter speed is directly related to the aperture (my camera only has 2 aperture settings; F/2.8, and F/8.0), when i try setting the shutter speed to 1/100,000 the exif says its somewhere around 1/74,000th of a second. again i have no way to test this as theres no timer that can do that, any ideas for confirming how short the shutter speed actually is? i mean the exif says 1/74,000th of a second but the exif has also claimed a 136 second exposure while its really limited to 65 seconds.
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Offline ixus

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #3 on: 20 / February / 2008, 17:55:07 »
To test upper limit ISO:
1) Put the camera on a table or a stable surface, pointing to a artifically and constant lighted scene. Set manual ISO to 1600. Press shutter halfway and take a note of aperture/shutter. Set these values manually in Allbest.
2) Take a picture.
3) Set ISO manually to higher values in Allbest, take as many pictures as you want to test.
4) Go to playback mode and go through the pictures with histogram on (press Disp in playback mode twice). If the pictures were taken with higher ISO levels, you should see the peaks in histogram move to the right as pictures get lighter and lighter.

In my tests I can't go beyond  ISO 1600.

My guess would be exposure bracketing limit would be your shutters speed limits. (65"-1/1500").

SD1000 has only 1 f stop, f/2.8. The f/8.0 is simulated through ND filter. ((http://chdk.setepontos.com/index.php/topic,548.0.html))

You would test shutter speed same as ISO speed test I outlined. I have only been able to get max shutter speed at 1/1500".  Correction: 1/10,000". The display reads 1/1500", but the shutter speed can be set to roughly 1/10000". I say roughly because I have no exact way to measure it, I am going by histogram readings and picture brightness.
« Last Edit: 22 / February / 2008, 11:00:44 by ixus »
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Offline Barney Fife

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #4 on: 20 / February / 2008, 21:21:20 »
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« Last Edit: 22 / April / 2008, 12:26:47 by Barney Fife »
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Offline chaynlynk

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #5 on: 22 / February / 2008, 06:22:23 »
I've been able to hit 6400 iso easily on my SD1000. I did that by overriding the propcase directly.
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Offline Barney Fife

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #6 on: 22 / February / 2008, 07:51:57 »
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« Last Edit: 22 / April / 2008, 12:27:06 by Barney Fife »
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[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye
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Offline ixus

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #7 on: 22 / February / 2008, 16:50:33 »
ISO 6400 CONFIRMED! Thanks to chaynlynk's post

Use Propcase tester script from here: UBASIC/Scripts: a property case value tester - CHDK Wiki

Use the propcase 149 for ISO, further explained here (see digicIII section torwards bottom of page):
PropertyCase - CHDK Wiki

Unable to set via AllBest build #35.

« Last Edit: 22 / February / 2008, 17:22:10 by ixus »
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Offline chaynlynk

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #8 on: 25 / February / 2008, 18:29:21 »
lol there you go. :) I didn't have the guts to take it any higher. I'm guessing it can. I'm just not sure if it would damage the CCD. Besides, based on the quality of the pictures at 3200 and 6400, I wouldn't even bother with those higher ISOs. I suppose if you were is some really REALLY dark lighting, and you couldn't use the 60 second exposure... maybe you could use 6400.
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Offline ixus

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Re: Allbest - SD1000 ISO and shutter speeds incorrect?
« Reply #9 on: 25 / February / 2008, 20:26:00 »
Yeah, thanks for the heads up, chaynlynk.
Anything above 6400 hangs the camera. Non-standard values other than ISO3200/6400 like ISO2000/2500 gives a purple picture.

I've been thinking, in Video mode there is a brightness setting. I wonder if that can be overriden and increased somehow? ISO6400 video would be nice. I went through the Property Pages and not found anything. Any ideas?

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