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Old Jun 7, 2010, 2:30 AM   #1
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Default can't increase shutter speed! PLZ HLP!!!

Hi all,
I bought Canon SX120 and I'm quite happy with it. But the problem is I can't increase shutter speed above 1/20. If I do, getting very dark very badly exposed pix. what should I do? Increase ISO???
PLZ hlp! I'm newbee.......and this is my 1st digicam!
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Old Jun 7, 2010, 5:16 AM   #2
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You're indoors right?

Turn on your flash. ;-)

If you try to use a shutter speed that's too fast for the widest available aperture (smallest f/stop number available with your lens), lighting and ISO speed set, you'll get an underexposed (too dark) image.

You have 4 main variables to take into consideration for exposure (and I use the term "main" since there are a lot of nuances to how you measure the light (for example, your metering mode), as well as different film characteristics if shooting film, and camera settings if shooting digital for the desired tone/contrast curve within an image and more). Once you have a better idea of how these 4 variables work together to give you a properly exposed image, the other fancy features will make more sense. These variables are light, aperture, ISO speed and shutter speed.

1. Light is typically measured as EV for Exposure Value in Photography.

2. Aperture (which works similar to the pupils in your eyes, where you can open up the aperture iris wider to let in more light, or close it down to let in less light). If you let in more light with a wider aperture, you can expose the film or sensor faster. If you let in less light with a smaller opening, it takes longer to expose the film or sensor. Note that aperture is normally expressed as f/stop, which is a ratio between the focal length of the lens and the diameter of the aperture iris. So, smaller values represent a larger iris diameter.

When you vary the aperture, you're controlling the iris in the lens (which like a pupil in your eye, can be opened up to let in more light or closed down to let less light in). So, this impacts the shutter speeds you'll need for proper exposure (since more or less light is getting through to the sensor). Aperture also impacts Depth of Field.

The aperture scale in one stop increments (with larger than f/1 apertures possible but very rare in lenses) goes f/1.0, f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0, f/11, f/16, f/22... With each one stop move to a smaller aperture (represented by higher f/stop numbers), you will need shutter speeds twice as long for proper exposure for the same lighting and ISO speed (only half the light gets through compared to a one stop larger aperture). Your SX120's lens has a widest available aperture of f/2.8 at it's widest zoom setting, dropping down to f/4.3 as you zoom in more (as most lenses lose light at longer focal lengths.

3. ISO speed. This is how sensitive the film or sensor is to light and is the same thing as the older ASA rating for film. The higher the ISO speed, the faster you can expose it (each time you double the ISO speed, you can use shutter speeds twice as fast for the same lighting and aperture.

4. Shutter Speed (how long the camera's shutter stays open to expose the film or sensor).

IOW, it all boils down to how sensitive the film or sensor is to light (which you control via the ISO or ASA speed of the film you use with film, or the ISO speed settings you use with digital), and how much light you need to let it see to "expose" the image (which you control via the aperture opening size and shutter speed).

These exposure calculators and simulators may help you understand it better. But, you'll need to be in brighter lighting, and using a higher ISO speed, and using a wider aperture to get shutter speeds anywhere near fast enough to freeze any subject movement indoors without a flash with most cameras.

http://www.calculator.org/exposure.aspx

http://www.photonhead.com/simcam/shutteraperture.php

With your type of camera, you'll want to use a flash indoors unless you're shooting a stationary (non moving subject), since you won't have enough light indoors for faster shutter speeds without increasing ISO speed to a very high level (which will degrade image quality), and even then, you'll probably still have motion blur from subject movement.

Using a flash avoids that, letting you keep your ISO speeds set to a lower value. Then, the flash can freeze the action, since the subject would only be properly exposed during the very short flash burst (usually 1/1000 second or faster).
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Old Jun 9, 2010, 2:22 PM   #3
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Thanks a lot fro ur help!
Would u plz tell me how to capture Lightning with SX120? Is it possible?

And here is my photostream:
http://www.flickr.com/photos/hirak_s...7624209868380/

PLZ help me to correct my photos.
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