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Old Sep 26, 2005, 2:09 AM   #1
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Hey All,

I did not see anyone mention this problem so I am curious as to if I have a defective Canon SD550. When the camera is focused on an area with low light, the LCD frames per second drop tremendously and it is very choppy. However, when I am somewhere with a lot of light, the LCD is extremely fluid. I also noticed that I do not have this problem in the movie mode. It is always fluid in movie mode, and only gets choppy in the normal photo shot modes with low light.

I had an SD300 before this camera and I never had this problem. The pictures on the camera seem to be fine but I take most of my pictures in low light conditions so having the LCD be choppy all the time is extremely annoying. Has anyone else had this problem with their SD550? Is this normal on the models? Is there some option I can change so that the LCD is more fluid?

Thanks for any help in advance!

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Old Sep 26, 2005, 8:18 AM   #2
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This is normal behavior for many camera models.

In low light, most cameras (unless their displays get very dim in low light) do two things to "gain up" the display.

One is to amplify the signal from the CCD (just like increasing ISO speed). This makes the display look grainy in low light from more noise.

The other is to slow down the refresh rate (allowing more time for the "pixel wells" to fill before reading the signal from the CCD).

If they didn't do this in low light, you'd have a very dark display. Think of how dark a photo would look indoors if you tried to take it at 1/60 second without a flash. You'd have a veryunderexposed image, because not enough light would have struck the sensor to properly expose the image (much longer shutter speeds would be required indoors without a flash).

If manufacturers tried to read the CCD at 60 frames per second in low light, the same thing would happen (you'd have adark display).

So, they slowdown the refresh rate (how often they are "emptying" the CCD) to allow more time for photons from the light sources to strike the photosites in the CCD to allow a stronger signal to be built up before reading it again.

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Old Sep 26, 2005, 11:42 PM   #3
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Wow. Awesome explanation!
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Old Sep 27, 2005, 1:49 AM   #4
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Agreed. Thanks!
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