... is 1/100K accurate?

shinnen

169

« 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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waterwingz

12128

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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shinnen

169

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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