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Old Sep 20, 2003, 9:23 AM   #1
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Default problem with Casio QV-5700 ISO 800 equivalent

Hi


When I use ISO 800 or 400 combine with a slow shutter speed (for example 25s or more) appears a small white circle in the top left corner!!

This is normal or my machine is broken??


thanks...
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Old Sep 20, 2003, 10:25 AM   #2
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Default Re: problem with Casio QV-5700 ISO 800 equivalent

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Originally Posted by xpress_on
When I use ISO 800 or 400 combine with a slow shutter speed (for example 25s or more) appears a small white circle in the top left corner
Just tried my QV-5700 with 30s f/8 at ISO800 pointing into a dark cupboard, and there are no spurious white circles. In fact I was astonished at the quality I got - I've been disappointed with noise at ISO800 when I've tried it in ordinary daylight at short speeds.

I did have to swap my first QV-5700 for another when I discovered a few bad pixels that appeared as a bright green spot on a grey slate roof. Fortunately it was only a week old and my retailer changed it without question. I note that other makes suffer from bad pixels sometimes.

Are you sure you can't detect the problem under any other conditions? What does the defect look like at high magnification?
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Old Sep 20, 2003, 11:09 AM   #3
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Default Re: problem with Casio QV-5700 ISO 800 equivalent

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[In fact I was astonished at the quality I got - I've been disappointed with noise at ISO800 when I've tried it in ordinary daylight at short speeds.
Oops! On looking at the exif data I see I'd failed to turn the ISO up from my usual ISO100, so no wonder the quality was good.

I've now done it again, at ISO800 this time, and got the expected very noisy image, but no spurious white circles.

Curiously, both the ISO100 and 800 versions are quite nicely exposed shots of the inside of a cupboard, though they were both 30s, f/8, an exposure chosen entirely at random - 30s to test the noise, and f/8 to get some depth of field.
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Old Sep 20, 2003, 11:36 AM   #4
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http://xpress.instantlogic.com/itemBrowse.ilx?idContainer={CF22897D-3148-4A05-A1E7-9DF2C4BD9AE1}


I was just taking some shots to see how the QV-5700 works in low light conditions, and to see the noise effects of each ISOīs mode. Then I realise that a big whit circle appears always in the top left corner when I use the ISO 800 or 400 and more than 20s / F8.
(this only happen in iso 800 and 400).


I bought my QV-5700 just on week ago and I what to make shore that this is really a problem on the camera and not just something that I did wrong.



By the way, Iím from Portugal and my English is no very good but I really need help to solve this problem.
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Old Sep 20, 2003, 8:25 PM   #5
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Default Try cross-posting this problem

I've looked at the 3 images you posted on the link you gave.

1. Are these photos of the night sky? What are they? Your test shots need to be of something very dark to show defects at such a long exposure. Any spurious light source might give an extra bit of unwanted image. I have been photographing the Moon and Mars with my QV-5700, but I didn't need long exposures like these.

2. Are you sure there wasn't a light source or a bit of flare (light shining on the lens and reflecting into it)?

3. How often are you going to use >25 sec exposures at ISO800? Why not use a lower ISO value, because you're only going to be recording self-luminous objects anyway.

Like you, I tested the various ISO speeds, and took many test shots with my new camera. However, I didn't explore as far as 30s at ISO800! You'll get more answers if you post this message in General Q&A as well - there's very few people look at the Casio forum, and there are very few QV-5700 owners (possibly only me). In the General Q&A forum they'll all ask you for more details of the test shots.
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Old Sep 21, 2003, 3:05 AM   #6
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Those 3 images were taken in my room with all the windows and doors closed.
The red light that you see is from my TV. All the images were been taken in the same conditions, without any light and you can see that in the first one the white circle doesnít appears.

I really donít care about de ISO800 in long exposure mode.

I bought this camera just one week ago and Iím afraid that in the future this error start to happen in all my photos, even in lower ISOīs values.

If this is not happening with your camera I must conclude that something is wrong with my QV-5700.

Thanks for the help. 
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