... is 1/100K accurate? - General Help and Assistance on using CHDK stable releases - CHDK Forum
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... is 1/100K accurate?

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Offline shinnen

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... is 1/100K accurate?
« on: 08 / October / 2017, 18:39:25 »
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Hi,
     When I set the fastest shutter speed for my a590, it says 1/100K seconds. Does anyone know if this is a (close to) accurate number. Just curious.
....... john
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Offline waterwingz

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Re: ... is 1/100K accurate?
« Reply #1 on: 08 / October / 2017, 19:46:30 »
Quote from: shinnen on 08 / October / 2017, 18:39:25
When I set the fastest shutter speed for my a590, it says 1/100K seconds. Does anyone know if this is a (close to) accurate number.
Almost certainly not - sorry.  At some point the shutter speed just stops increasing regardless of the value you select.

You can test this a bit by taking pictures of a constant image as you advance the shutter speed.  Remember to lock the ISO and aperture too so that the Canon firmware does not change those.
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Offline shinnen

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Re: ... is 1/100K accurate?
« Reply #2 on: 10 / October / 2017, 15:12:55 »
Hi Waterwingz,
         Alright, I did a rough test, as you suggested. For the test I pointed the camera at a Helical 15W (lit) fluorescent bulb. I set the camera at iso 30, aperture 4.49, and varied the speed from 1/100K to 1/2.5k seconds (by CHDK setting)
Here's what I saw.
 Speed       Brightness
1/100K .... base line
1/80K   .... no change
1/64k   .... no change
1/50k   .... slightly brighter
1/32k   .... no change
1/25K to 1/2.5k brighter with each decrease in speed.
 
There's an increase in brightness at 1/50K, which is consistent after 1/25k.
P.S. I can send you the photos if you like.
..... john
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Offline shinnen

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Re: ... is 1/100K accurate?
« Reply #3 on: 11 / October / 2017, 10:41:47 »
Can I assume that no one wants these images?
.... john
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Offline waterwingz

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Re: ... is 1/100K accurate?
« Reply #4 on: 11 / October / 2017, 11:30:04 »
Quote from: shinnen on 11 / October / 2017, 10:41:47
Can I assume that no one wants these images?
.... john
Yes
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Offline shinnen

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Re: ... is 1/100K accurate?
« Reply #5 on: 11 / October / 2017, 14:55:05 »
Thanks.
I will delete them.
.... john
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